Green biotechnology, nanotechnology and bio-fortification: perspectives on novel environment-friendly crop improvement strategies.

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Green biotechnology, nanotechnology and bio-fortification: perspectives on novel environment-friendly crop improvement strategies a

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Shikha Yashveer , Vikram Singh , Vineet Kaswan , Amit Kaushik & Jayanti Tokas

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Department of Molecular Biology & Biotechnology, College of Basic Sciences & Humanities, CCS HAU, Hisar, Haryana, India

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Department of Genetics & Plant Breeding, Wheat Section, College of Agriculture, CCS HAU, Hisar, Haryana, India c

Department of Biotechnology, College of Basic Science & Humanities, SDAU, Sardarkrushinagar 385506, Gujarat, India d

Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India e

Department of Biochemistry, College of Basic Sciences & Humanities, CCS HAU, Hisar, Haryana, India Published online: 19 Jan 2015.

To cite this article: Shikha Yashveer, Vikram Singh, Vineet Kaswan, Amit Kaushik & Jayanti Tokas (2015): Green biotechnology, nanotechnology and bio-fortification: perspectives on novel environment-friendly crop improvement strategies, Biotechnology and Genetic Engineering Reviews, DOI: 10.1080/02648725.2014.992622 To link to this article: http://dx.doi.org/10.1080/02648725.2014.992622

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Biotechnology and Genetic Engineering Reviews, 2015 http://dx.doi.org/10.1080/02648725.2014.992622

Green biotechnology, nanotechnology and bio-fortification: perspectives on novel environment-friendly crop improvement strategies Shikha Yashveera, Vikram Singhb, Vineet Kaswanc*, Amit Kaushikd and Jayanti Tokase


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Department of Molecular Biology & Biotechnology, College of Basic Sciences & Humanities, CCS HAU, Hisar, Haryana, India; bDepartment of Genetics & Plant Breeding, Wheat Section, College of Agriculture, CCS HAU, Hisar, Haryana, India; cDepartment of Biotechnology, College of Basic Science & Humanities, SDAU, Sardarkrushinagar 385506, Gujarat, India; dAmity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India; eDepartment of Biochemistry, College of Basic Sciences & Humanities, CCS HAU, Hisar, Haryana, India (Received 13 September 2014; accepted 24 November 2014) Food insecurity and malnutrition are prominent issues for this century. As the world’s population continues to increase, ensuring that the earth has enough food that is nutritious too will be a difficult task. Today one billion people of the world are undernourished and more than a third are malnourished. Moreover, the looming threat of climate change is exasperating the situation even further. At the same time, the total acreage of arable land that could support agricultural use is already near its limits, and may even decrease over the next few years due to salination and desertification patterns resulting from climate change. Clearly, changing the way we think about crop production must take place on multiple levels. New varieties of crops must be developed which can produce higher crop yields with less water and fewer agricultural inputs. Besides this, the crops themselves must have improved nutritional qualities or become biofortified in order to reduce the chances of ‘hidden hunger’ resulting from malnourishment. It is difficult to envision the optimum way to increase crop production using a single uniform strategy. Instead, a variety of approaches must be employed and tailored for any particular agricultural setting. New high-impact technologies such as green biotechnology, biofortification, and nanotechnology offer opportunities for boosting agricultural productivity and enhancing food quality and nutritional value with eco-friendly manner. These agricultural technologies currently under development will renovate our world to one that can comfortably address the new directions, our planet will take as a result of climate change. Keywords: malnutrition; transgenic; vitamin deficiency; green innovations; precision farming

1. Introduction Bringing to an end, food insecurity, hunger, and malnutrition is a pressing global priority. The current global architecture for governing food, nutrition, and agriculture has not been able to adequately address the challenges the system now faces and ensure progress toward food security. New high-impact technologies such as Green Biotechnology, Biofortification, and Nanotechnology now offer opportunities for boosting agricultural *Corresponding author: Email: [email protected] © 2015 Taylor & Francis


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productivity and enhancing food quality and nutritional value. Plant varieties are required which are capable of surviving and even thriving in a variety of rapidly changing and extreme environmental conditions. Much attention has been placed on generating crops which are tolerant to heat, drought, and other environmental stresses. The methods by which scientists are addressing this challenge are creative and green to say the least. Plant architecture, for example, can be modified to enable plants to resist adverse environmental conditions. The shape, distribution, and consistency of plant roots and leaves can be designed to better catch and retain water in times of extreme drought. Roots can be altered for shallow growth so that they remain close to the surface, the better to collect dew and runoff from precipitation. Similarly, leaves can be modified to trap moisture from escaping by strictly controlling their stomata (pores) (Bhatnagar-Mathur, Vadez, & Sharma, 2008; Somvanshi, 2009; Tester & Langridge, 2010). Plants with modified photosynthetic machinery can be tailored to be more receptive to changing weather patterns. This is a considerable challenge, resting on the hope that ‘greener’ innovations – mostly based on molecular biology and genetic manipulations of plants – will be environmentally safer, although this is not a straightforward path in many cases. At the same time, efforts are being made on the breeding of new varieties of staple crops that are rich in micronutrients (biofortification). New high-impact technologies, such as nanotechnology and its applications, might allow people to eat foods without absorbing harmful allergens and cholesterol, and modifies food taste and nutritional value. For such technologies, however, research efforts should be devoted to carefully studying both benefits and hazards early on in the application process. Nanotechnologies, genomics, and electronics can also be useful for improving disease diagnostics, the delivery of pesticides, fertilizers, and water, or for monitoring and managing soil quality. 2. Green biotechnology Green biotechnology is defined as the application of biological techniques to plants with the aim of improving the nutritional quality, quantity, and production economics. Green Biotechnology can help farmers produce food sustainably through: 2.1. Less fuel consumption on farms Genetically modified (GM) herbicide tolerant (HT) crops help farmers by reducing the need to plough fields in preparation for planting crops saving fuel. This resultant reduction in tractor use also helps to protect the structure of the soil which reduces erosion. The agricultural practice of ploughing is also known as ‘tillage’. The adoption of reduced tillage or no-tillage systems in respect of fuel use results in reductions of carbon dioxide emissions. In addition, GM insect resistant crops have been developed to require fewer insecticide treatments. This in turn means a reduction in fuel use and lower CO2 emissions since farmers need to spray pesticides less frequently on their fields. 2.2. Carbon sequestration As previously mentioned, crops developed with agricultural biotechnology reduce the need for tillage or ploughing, allowing farmers to adopt conservation or ‘no-till’ farming practices. As a result, over time soil quality is enhanced and becomes carbon-enriched

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since more crop residue can be left on the fields. In addition, since the soil is not inverted by ploughing, less carbon in the soil becomes oxidised through exposure to the air and therefore less CO2 is released into the atmosphere. In 2007, the no-till area nearly doubled in the US and a 5-fold increase was recorded in Argentina, with GM HT soybeans. Besides soil preservation, no-tillage agriculture saves fossil fuel use in tractors, and decreases the economic costs and environmental impact of productive farming. According to Barfoot and Brookes (2009), the additional amount of soil carbon sequestered since 1996 has been equivalent to 83,179 million tonnes of carbon dioxide which would otherwise have been released into the global atmosphere. GM HT technology has been a key contributor to this increase in soil carbon sequestration, though it is not the only influential factor. 2.3. Reduced fertilizer use Today around 120 teragrams (Tg) of nitrogen are chemically fixed every year, around 80% of which is used as agricultural fertilizer (Galloway et al., 2003, 2004). Typical nitrogen-use efficiencies for wheat, rice, and maize indicate that around 66% of this nitrogen is lost to the environment either in the form of nitrous oxides, which are potent greenhouse gases, or as soluble nitrates that find their way into aquatic systems. Around 100 million tonnes is deposited globally in terrestrial, freshwater, and marine environments every year, a threefold increase over preindustrial levels (Galloway et al., 2008; Rockström et al., 2009). Nutrient excesses are especially large in China, northern India, USA, and western Europe, leading to widespread nutrient pollution (Foley et al., 2011). In addition, it is predicted that the energy-intensive production of nitrogen fertilizers will consume around 2% of global energy by 2050. For all these reasons, it is desirable to reduce agricultural reliance on nitrogen fertilizers. However, reducing reliance on agricultural fertilizers must be balanced with the predicted requirement of doubling agricultural productivity to meet the demands of a growing global population with changing consumption patterns (Beddington, 2010). Different biotechnological approaches can be used to reduce fertilizer use: 2.3.1. Nitrogen use efficiency technology Crops which are efficient in nitrogen usage and/or have lower nitrogen requirements are much needed. GM rice and canola has been developed that uses nitrogen more efficiently, so the plants need less fertilizer. This so-called ‘nitrogen use efficiency’ technology produces plants with yields equivalent to conventional varieties but which require significantly less nitrogen fertilizer because they use it more efficiently. This technology has the potential to reduce the amount of nitrogen fertilizer lost by farmers every year due to leaching into the air, soil, and water ways. 2.3.2. Engineering cereal crops to fix their own nitrogen A biotechnological approach where cereal crops are engineered to fix nitrogen has the potential to reduce fertilizer use and greatly reduce the environmental impact of increasing yields. However, replacing nitrogen fertilizer would require levels of nitrogen fixation in cereals equivalent to those that occur in legumes, and would therefore be extremely challenging. There are multiple biotechnological approaches currently being explored that could deliver fixed nitrogen to cereal crops (Beatty & Good, 2011; Oldroyd & Dixon, 2014).


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One scenario focuses on engineering is a nitrogen fixing symbiosis in cereal roots, either through transferring the legume-rhizobial interaction to cereals or through improving pre-existing associations in cereal roots. Alternatively, the nitrogenase enzyme itself could be introduced into organelles of plant cells to create a new nitrogen-fixing capability. This is an attractive solution and is currently underway in at least two major projects but has two notable challenges. Firstly, nitrogenase is a highly complex enzyme and would require the coordinated expression of at least 16 nif genes (Temme, Zhao, & Voigt, 2012). Secondly, nitrogenase activity has high energetic demands but while aerobic respiration is therefore essential, nitrogenase is irreversibly denatured by oxygen. Unlike symbiotic nitrogen fixation, no eukaryotes have evolved a nitrogen-fixation capability, despite plastids being derived from endophytic cyanobacteria. This might indicate that there are fundamental barriers to nitrogenase activity in plant plastids. Engineering a nitrogen-fixing symbiosis can provide solutions to these problems found in nature, by adapting existing signalling and developmental mechanisms to provide a suitable environment for nitrogenase activity in the plant nodule. Both of these approaches are highly challenging and it is unlikely that in the short term any plant will deliver the levels of fixed nitrogen equivalent to fertilizer application rates in the developed world. However, even low levels of nitrogen fixation could be transformative for crop yields in the developing world. It is hoped that these biotechnological approaches may gradually reduce the requirement in agriculture for inorganic fertilizer. 2.4. Crop adaptation to water use efficiency Agriculture accounts for 70% of all water use; if current trends continue, predicted water shortages in agriculture have been identified as the single most significant constraint on crop production over the next 50 years. Agricultural biotechnology can play a significant role in enabling farmers to improve yield by using water more sustainably and helping to cope with water scarcity. This works in two main ways: 2.4.1. Minimising water loss from agriculture Agricultural biotech practices have been developed to reduce the amount of ploughing required before planting their crops. This means the soil surface is not inverted which helps to trap soil moisture. Under drought conditions this can mean the difference between having a crop to harvest and crop failure. 2.4.2. Improving drought tolerance Plants react to stresses such as drought by consuming large quantities of stored energy normally used for growth and seed production. Drought conditions can, therefore, drain the plant’s energy reserves, resulting in irreversible damage to the plant or even death. Agricultural biotechnology practices which improve drought tolerance have an immediate positive impact on the plant’s resilience and the energy available to it for growth to maturity and seed production. Drought-tolerant maize has now entered the regulatory phase of development in the US, demonstrating that a GM solution to this important issue is well beyond the theoretical stage. The Water Efficient Maize for Africa partnership, led by the African Agriculture Technology Foundation, is a five-year public–private partnership aiming to develop new African drought-tolerant maize varieties incorporating the best technology available


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internationally. The national agricultural research systems, farmer’s groups, and seed companies participating in the project will contribute their expertise in field testing, seed multiplication, and distribution. The current timing for the availability of the crop is 2017. Kenya has recently announced its intention to commence field trials with this type of maize. Hybrid crops have been developed to tolerate drought and periodic water deficits. Over the next decade, several companies plan to introduce GM crops that will further improve drought tolerance.


2.5. Increased photosynthetic activity Corn and sugarcane grow like weeds. They typically get yields that are about 70% higher, need less water, less nitrogen, and are less vulnerable to the droughts than wheat and rice. Corn and sugarcane have the advantage of a form of photosynthesis called C4 instead of C3. Plants that use C3 photosynthesis have to open their pores to absorb CO2 during the heat of the day, while the sun is shining on them. As a result, they lose moisture to the warm air. Plants that use C4 photosynthesis inhale carbon dioxide at night, when it’s cool, and save it for combining with sunlight during the day. By doing that, they hang on to more water and capture almost twice as much of the sun’s energy as calories than C3 plants. And the system they have to turn CO2, water, and sunlight into sugars needs 30% less nitrogen than the system in C3 plants. Now an international team of scientists funded in part by the Bill and Melinda Gates Foundation is working to move the genes for C4 photosynthesis from corn and sugarcane into rice – ‘C4 Rice’ (http://www.irri.org/c4 rice). If the projects succeed, there will be rice and wheat that produce one and a half times the yield per acre, that require less water per calorie, that need less fertilizer per calorie, and that are more resistant to drought. The C4 genes are totally natural. What the C4 rice project is doing, in a sense, is cross-breeding rice with the plants that have evolved to use C4. The resulting crop will be more than 99.9% rice, but with the energy capturing genes that evolved in thousands of other plants, and have been present in nature for 30 million years. Another example where there is enhanced utilization of solar energy is of winterbeet. At present, sugarbeet is sown in the spring and harvested in the fall. The vegetation period can be prolonged when the beets are already sown in the fall, making it possible to increase the sugar yield by 20 to 30 percent due to better photosynthetic efficiency. However, the development of a cold-resistant beet is no easy task. Not just because a beet of this kind has to withstand frost and cold, it can also not be allowed to produce any undesired inflorescence (‘bolters’). In order to prevent bolting and flowering triggered by cold stimulus, certain genes involved with these processes have to be activated or shut off. Many years of research and development will be needed before cold-resistant sugarbeet varieties can make their way to the market. 3. Biofortification Unfortunately, agricultural systems have never been explicitly designed to promote human health and, instead, mostly focus on increased profitability for farmers and agricultural industries. Agriculture met the challenge of feeding the world’s poor during the ‘Green Revolution,’ focusing primarily on three staple crops rice (Oryza sativa L.), wheat (Triticum aestivum L.), and maize (Zea mays L.). These crops provided enough


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energy to prevent widespread famines in many developing nations. An unforeseen consequence of that agricultural revolution was the rapid rise in micronutrient malnutrition in many nations that adopted the cropping systems that prevented large-scale starvation. Humans require at least 44 known nutrients in adequate amounts and consistently to live healthy and productive lives. Many agricultural tools (e.g. diversification, crop selection, fertilizers, cropping systems, soil amendments, small livestock production, aquaculture, etc.) could be used to increase the nutrient output of farming systems. Biofortification (developing food crops that fortify themselves) is the first agricultural tool now being employed to address micronutrient malnutrition worldwide. Biofortification is a process for increasing the bioavailable concentrations of essential elements in the edible portions of crops. Biofortification capitalizes on the consistent daily intake of food staples, thus indirectly targeting low-income households who cannot afford a more diverse diet. After the initial investment of developing fortified crops, no extra costs are met, making this strategy very sustainable. Furthermore, the improved varieties can be shared internationally. Biofortified seeds are also likely to have an indirect impact in agriculture, as a higher trace mineral content in seeds confer better protection against pests, diseases, and environmental stresses, thereby increasing yield (Welch & Graham, 2004). Biofortification is not a panacea in itself but a very important complement to dietary variety and to supplementation. 3.1. Crops for biofortification A significant portion of the developing world’s population relies largely on one or more of the staple crops such as rice, maize, wheat, and non-cereal food crops such as potato and cassava for their nutrition, and these are the subject of biofortification projects, both by conventional breeding and by modern biotechnology methods. 3.2. Methods to achieve biofortification Biofortification can be achieved either by conventional breeding or genetic modification, both approaches have unique capabilities and constraints. A plant breeding strategy is a long-term process requiring substantial effort and resources, but is a sustainable and cost-effective approach useful in improving micronutrient concentrations. Substantial genetic variation is the basis for crop improvement through plant breeding strategies (Ortiz-Monasterio et al., 2007). Adequate genetic variation in concentrations of β-carotene, other functional carotenoids, iron, zinc, and other minerals exists among cultivars, making selection of nutritionally appropriate breeding materials possible. Also, micronutrient-density traits are stable across environments. In all crops studied, it is possible to combine the high-micronutrient-density trait with high yield, unlike protein content and yield, which are negatively correlated; the genetic control is simple enough to make breeding economic. Therefore, it is possible to improve the content of several limiting micronutrients together, thus pushing populations toward nutritional balance. Conventional breeding has been employed in different parts of the world for enhancing the levels of provitamin A carotenoids in cassava, sweet potato, iron in cassava, banana and beans, and zinc in rice, pearl millet, and wheat. Many of the biofortified products are now available in the market and are well accepted in rural population. In spite of the gains that have been made in using conventional breeding for biofortification, there are limitations to the use of the technique including the very limited


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number of traits that can be improved at the same time, available genetic variation for the trait, and the long period required. Transgenic approaches are advantageous when the nutrient does not naturally exist in a crop (e.g. provitamin A in rice) or when sufficient amounts of bioavailable micronutrients cannot be effectively bred into the crop. However, once a transgenic line is obtained, several years of conventional breeding are needed to ensure that the transgenes are stably inherited and to incorporate the transgenic line into varieties that farmers prefer. Genetic modification allows more traits to be improved in much shorter periods of time and attains much higher levels of nutrient enhancement relative to conventional breeding. While transgenic breeding can sometimes offer micronutrient gains beyond those available to conventional breeders, many countries lack legal frameworks to allow release and commercialization of these varieties. 3.3. Examples of biofortification projects 3.3.1. Biofortification for increased protein content Human cells can produce only 10 out of the 20 amino acids, the building blocks of proteins, and so the missing essential amino acids must be supplied in the food. As the body cannot store excess amino acids, their intake must be daily. In many poor developing countries, the daily intake of essential amino acids is often not sufficient due to the scarcity of high-protein sources such as meat, fish, or soybean. Rice, cassava, and potato are important sources of carbohydrates, but they are low in protein content. Suitable protein candidates for biofortification include the storage protein Sporamin A from sweet potato, the seed albumin AmA1 protein from Prince’s Feather (Amaranthus hypochondriacus), and ASP1, an artificial storage protein rich in essential amino acids. ASP1 has been introduced and expressed successfully in rice and cassava, and efforts are under way to optimize expression and increase the level of protein accumulation in transgenic plants. 3.3.2. Combating vitamin A deficiency Vitamin A deficiency, particularly prevalent among children in Africa and southeast Asia, causes irreversible blindness, and increased susceptibility to disease and mortality. Orange sweet potato (OSP), rich in vitamin A, is the first biofortified crop to be released. OSP varieties that are suited to African tastes and environments have been developed and distributed in parts of Africa where prevalence of vitamin A deficiency is high and where white or yellow varieties – which provide little or no vitamin A – are traditionally consumed. Rice plants produce β-carotene (provitamin A) in green tissues, but not in the seeds. A public–private partnership to produce rice varieties rich in provitamin A culminated in the development of golden rice, in which two genes were introduced by genetic engineering. These encode the enzymes phytoene synthase (PSY) and phytoene desaturase (CRTI). Golden rice 1 contains the PSY gene from daffodil (Narcissus pseudonarcissus) and the CRTI gene from the bacterium Erwinia uredovora, both expressed only in the rice seed (Ye et al., 2000). Replacing PSY with genes from maize and rice increased the level of β-carotene by 23 times in golden rice 2 (Paine et al., 2005). Half the daily recommended allowance of vitamin A for a 1–3 year old child would therefore be provided for in by 72 g of golden rice 2.

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In addition to rice, other crops engineered for higher β-carotene content include potato, canola, tomato, carrot, and cauliflower (Diretto, Al-Babili, & Tavazza, 2007; Sautter, Poletti, Zhang, & Gruissem, 2006). The first generation of provitamin A-rich orange open-pollinated maize varieties developed using conventional breeding was released by the Institute for Agricultural Research in Nigeria in June 2012. A human bioavailability study using transgenic provitamin A banana began in late 2013 (http:// www.banana21.org/index.html). Queensland University of Technology and the National Agricultural Research Organization of Uganda are developing transgenic provitamin A bananas for Uganda. Bananas with up to 20 ppm provitamin A have been developed and trials have commenced in Uganda. Provitamin A bananas are expected to be released in 2019. The first field trials for a genetically engineered provitamin A biofortified cassava began in 2009. Delivery of the biofortified crops is expected in 2017. 3.3.3. Iron and zinc-rich crops Iron deficiency anemia affects more than 2 billion people in virtually all countries, which makes iron deficiency by far the most common micronutrient deficiency worldwide. Iron is found in vegetables, grains, and red meat. However, the bioavailability of iron in plants is low. In terms of biofortification, improvement of common bean is advantageous precisely because the baseline grain iron content is high at 55 ppm (mg/kg) and variability for the trait is great, ranging up to 110 ppm, allowing initial breeding attempts to be much more successful than in the cereals (Beebe, Gonzalez, & Rengifo, 2000). In addition, unlike many cereals that are polished before eating, resulting in significant loss of nutrients, common beans are consumed as a whole, thus conserving all their nutritional content. The target areas for biofortified beans are in iron deficiency anemia prone areas of Latin America and eastern and southern Africa where the crop is important and consumption is high, such as the Central America, northeast Brazil, and the Great Lakes region of Africa. The bioavailability of iron in rice is very low; the problem is aggravated by the presence of phytate, a potent inhibitor of iron resorption, and by the lack of iron resorption-enhancing factors. Therefore, scientists have had to increase the iron content in grains, reduce the level of phytate, and add resorption-enhancing factors. Expression of the iron storage protein ferritin from French bean and soybean in the endosperm of rice results in a 3-fold increase of iron in seeds. In order to decrease the level of phytate, an enzyme that degrades it (known as phytase) has also been transformed into rice, and efforts are currently under way to optimize the construct. Finally, over-expression of a cysteine-rich protein that transports metals in rice can improve the rate of iron resorption during digestion. A transgenic high-iron rice variety has been developed by the University of Melbourne and IRRI that contains 14 ppm iron in the white rice grain and translocates iron to accumulate in the endosperm, where it is unlikely to be bound by phytic acid and therefore likely to be bioavailable (Johnson et al., 2011). Teams at IRRI have produced several thousand transformants of IR64 and IR69428 that carry the soybean or rice ferritin and rice nicotianamine synthase (NAS2) over expression genetic constructs and, in the field, demonstrate the target level for iron and surpass that for zinc. Achieving the iron and now higher zinc levels in the field requires both a ferritin and NAS gene to be expressed correctly. The project at IRRI is now moving beyond proof of concept to product development for high-iron and high-zinc, highly adapted rice genotypes. Bioavailability trials are expected to begin next year, and release is projected for about 2022 in Bangladesh.



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Efforts to increase iron concentrations in wheat by conventional breeding have not been successful, and there are currently no iron-biofortified wheat varieties available for farmers. Whole wheat grain contains approximately 30 ppm iron, of which only 5% is estimated to be bioavailable. It is estimated that wheat requires an additional 22 ppm iron in the whole wheat grain, for a total concentration of 52 ppm iron, to adequately biofortify a wheat-based diet with iron. The University of Melbourne, Australia, has been employing an approach that has proven highly effective in rice, using NAS to increase iron concentrations in wheat and produce biofortified wheat varieties with 52 ppm iron in whole grain. The project places strong emphasis on multi-location field trials of wheat plants transformed with a rice nicotianamine synthase gene (OsNAS2) under regulatory control of the maize ubiquitin promoter, Ubi1, to provide proof of concept of the transgenics approach in wheat. Additionally, selectable marker-free transgenic populations will be developed and evaluated in commercially important wheat backgrounds. The John Innes Centre, Norwich UK, has been investigating several independent strategies to increase iron concentration and bioavailability in wheat grains through transgenic means. The approaches will target distinct stages and tissues including uptake from the soil, remobilization from vegetative tissue during grain filling, and accumulation within grains to enhance total iron in the grain (Borrill et al., 2014). A number of zinc rice advanced breeding lines for both Boro (irrigated) and T. Aman (rainfed) seasons are under development through a breeding program at the Bangladesh Rice Research Institute. The first zinc rice aman variety, ‘BRRI dhan 62,’ that contains 19 ppm of zinc and 9% protein and yields 4.2 tons per hectare (yield is similar to that of other popular, conventional varieties like BRRI dhan33 and BINA dhan7) was released in 2013. Crop duration from seed to seed is 112–115 days for BINA dhan7 and BRRI dhan33 while BRRI dhan62 can be harvested within 100 days, which is the shortest duration T. Aman variety in the country. BRRI dhan62 can also escape terminal drought because of its short duration. At least one zinc rice boro variety with 22–24 ppm is expected to be released in 2014. In India, the first varieties are expected to be commercialized in 2015. 3.4. Increased folic acid in tomato Folic acid deficiency is a global health problem that affects mainly, though not exclusively, women over the age of 30, and it is the main cause of anemia in at least 10 million pregnant women in developing countries. In food, most of the folic acid occurs as folate. In order to engineer tomatoes with higher level of folate, scientists have overexpressed in the fruit the genes encoding the enzymes catalyzing the synthesis of two folate precursors (Díaz de la Garza, Gregory, & Hanson, 2007). In plants both traits were combined by crossing, vine-ripened transgenic fruit accumulated up to 25 times more folate than controls. 4. Nanotechnology Nanotechnology could provide possible solutions to many of the major risks in agriculture. It could improve our understanding of the biology of different crops, thus potentially enhance yields and nutritional values with greater control over various plant diseases and pest incidences. It could also help in developing improved systems for monitoring environmental conditions and delivering nutrients and/or plant protecting

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chemicals in the needed concentrations, thus controlling various plant diseases in the right manner at the right time (Sharon, Choudhary, & Kumar, 2010). These applications of nanobiotechnology in agriculture are gradually moving from the theoretical possibilities into the applicable area and play an important role in improving the existing crop management techniques as follows:


4.1. Detection of plant diseases One of the major problems associated with plant disease management is the detection of correct stage of disease. Most of the times, plant protection chemicals such as fungicides and pesticides are applied only after the appearance of symptoms thus causing some significant crop losses. Hence, it is essential to detect and diagnose plant diseases at their early stage itself, so that plant protecting chemicals could be applied at correct dose at the right time thus avoiding residual toxicity and environmental hazards. Many of the molecular systems for the detection of micro-organisms are primarily based on specific nucleotide probe detection or on specific antibodies and such systems are highly sensitive and selective and hence mostly suited for laboratory uses only. Proper sensing systems that could detect and quantify pathogens in defined positions of the field would help the growers in site-targeted and optimized application of agrochemicals with minimal environmental hazards. In this scenario, nanobiosensors, once installed in the field, could detect pathogens with high sensitivity and specificity. Such nanosensors are highly potable systems with ‘real-time’ monitoring of results. They do not need extensive sample preparations and detection is label-free also (Sadanandom & Napier, 2010). Cell biologists of Cornell University are investigating on nanofabrication technologies to understand how the fungi and bacteria feel their way on plant surface, to induce infection (Mccandless, 2011). 4.1.1. Smart delivery systems for fertilizers, pesticides, and for the control of plant diseases Agrochemicals are conventionally applied to crops by spraying and/or broadcasting. In order to avoid the problems such as leaching of chemicals, degradation by photolysis, hydrolysis, and microbial degradation, a concentration of chemicals lower than minimum effective concentration to reach the target site of crops is required. The nanocapsulated agrochemicals are designed in such a manner that they hold all essential properties such as effective concentration, time-controlled release in response to certain stimuli, enhanced targeted activity, and less eco-toxicity with safe and easy mode of delivery, thus avoiding repeated application. The best example is the reduction of phytotoxicity of herbicides on crops by controlling the parasitic weeds with nanocapsulated herbicides (Pérez-de-Luque & Rubiales, 2009). 4.2. Improved germination Cañas and co-workers (2008) reported the effects of functionalized single-walled carbon nanotubes (SWCNTs) and non-functionalized SWCNTs on root elongation of six different crop species, such as cabbage (Brassica oleracea), cucumber (Cucumis sativus), carrot (Daucus carota), onion (Allium cepa), lettuce (Lactuca sativa), and tomato (Solanumly copersicum). They showed that the root elongation in onion and cucumber was enhanced by non-functionalized SWCNTs, and the interaction of both functionalized SWCNTs and non-functionalized SWCNTs with root surface, resulted in the



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formation of nanotube sheets on cucumber root surface, without entering into the roots. However, cabbage and carrot remained unaffected by either form of nanotubes. Furthermore, functionalized SWCNTs inhibited the root elongation of lettuce, while tomato was found to be most sensitive to non-functionalized SWCNTs with significant root length reduction, whereas a positive response has been shown on the seed germination and growth of tomato plants upon interaction with multi-walled carbon nanotubes (MWCNTs) (Khodakovskaya et al., 2011). They showed that the presence of MWCNTs increased water uptake by seeds which in turn enhanced the germination process. Similar positive effects of MWCNTs on seed germination and root growth of six different crop species – radish (Raphanus sativus), rye grass (Lolium perenne), rape (Brassica napus), lettuce (Lactuca sativa), corn (Zea mays), and cucumber (Cucumis sativus) – was also reported (Lin & Xing, 2007). Remya et al. (2010) also reported the positive effects of both SWCNTs and MWCNTs on the germination of rice seeds and observed an enhanced germination for seeds germinated in the presence of nanotubes. Nonetheless, the interaction of different nanomaterials with plants and their mechanism for genetic and molecular modification of plants are still unpredictable. The interaction of nanomaterials with plants differs with type and time of exposure to nanomaterials, so these facts should be kept in mind while performing nanotoxicity studies. Additionally, the orientation of nanotubes with respect to the plant cell wall might be important for their penetration, but the mode of entry of nanotubes through the cell wall remains mysterious which still needs more studies. 4.3. Agricultural diagnostics and drug delivery with nanotubes Agriculture is seasonal in nature and depends on many variables such as soil, crops, weather, etc. Sensing, acquisition, manipulation, storage, and transfer of reliable and accurate data about the plant and production handling environment is, therefore, crucial in managing this variability to optimize both inputs and outputs and reduce impacts on the environment to meet the demand for high and good quality products. Based on advances in nanotechnology research, a new scanning probe-based data storage concept called ‘millipede’ was developed that combines ultrahigh density, terabit capacity, small form factor, and high data rate. Other developments include nanosensors to monitor the health of crops and magnetic nanoparticles to remove soil contaminants. Dispersed throughout fields, a network of nanosensors would relay detailed data about crops and soils. The sensors will be able to monitor plant conditions, such as the presence of plant viruses or the level of soil nutrient. Nanofabricated devices offer the scope for their injection into plants to detect tissue parts affected by rare phenomena such as diseases, nutrient deficiency, and developmental abnormalities (Opara Linus, 2004). 4.4. Precision agriculture Precision agriculture refers to new farming methods based on optimizing resources and minimizing inputs, including water and fertilizer. Precision agriculture can include sophisticated devices such as global positioning system to identify factors ranging from moisture and nutrient content of soils to pest infestation of a given crop. Using this approach, optimal inputs can be applied to a specific region of a given crop when required, rather than uniformly and at predetermined times across the entire field, whether the crop requires inputs or not. The great advantage of this technique is the avoidance of overuse of pesticides, herbicides, fertilizer, and water (earthobservatory.nasa.gov, www.ghcc.msfc.nasa.gov). The

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same principles of precision farming can also be applied to developing countries, without the requirement of advanced technologies. For example, the concept of drip irrigation, a practice by which small amounts of water are applied to plant root systems by a network of irrigation pipes, has been demonstrated to work successfully for drought-prone areas. Similarly, some resource-poor countries utilize a farming technique whereby tiny amounts of fertilizer are applied to the roots of crops at specific times in the growing season. These low-tech farming practices have enabled farmers who have poor access to water or artificial fertilizers to make the most of their crop yield.


4.5. Developing transgenic plants with novel properties Nanotechnology has shown its ability in modifying the genetic constitution of plants by introducing novel genes, thus resulting in crop improvement. The application of fluorescent labeled starch-nanoparticles as plant transgenic vehicle, was reported in which the nanoparticle biomaterial was designed in such a way that it binded the gene and transported it across the cell wall of plant cells by inducing instantaneous pore channels in the cell wall, cell membrane, and nuclear membrane with the help of ultrasound (Jun et al., 2008). It is possible to integrate different genes on the nanoparticle at the same time and the imaging of fluorescent nanoparticle is possible with fluorescence microscope, thus understanding the movement of exterior genes along with the expression of transferred genes. It was reported that polyamidoamine (PAMAM) dendrimer acts as a nanocarrier for delivering genes into plant cells with intact cell wall. Supramolecular complexes of PAMAM dendrimer-DNA are formed through electrostatic interactions and these complexes are penetrated through the cell walls of turf grass calli, expressing foreign genes within the cells (Pasupathy, Lin, Hu, Luo, & Ke, 2008). Surface functionalized mesoporous silica nanoparticles (MSNs) provide new ways to precisely manipulate gene expression at single cell level by delivering DNA and its activators in a controlled fashion (Torney, Trewyn, Lin, & Wang, 2007) by penetrating through plant cell wall. MSNs are loaded with gene and its chemical inducer and the ends are capped with gold nanoparticles to protect the molecules from leaching out. Uncapping of capping agents results in stimuli responsive release of chemicals, thus triggering gene expression in plants. It is found that surface modification of MSNs with triethylene glycol promotes their easy penetration into cells and also allows plasmid DNA to absorb on MSN surface. In this method, the minimum amount of DNA required to detect marker expression is 1000-fold less than that required for the conventional delivery method and such delivery method has significant applications in various gene expression studies. Such nanoparticle-mediated plant transformation allows sitetargeted simultaneous delivery of both DNA and effector molecules. Future possibilities include enlargement of pore size and multifunction-alization of MSNs, which support site-targeted delivery of proteins, nucleotides and chemicals in plant biotechnology. The ability of carbon nanotubes to penetrate intact plant cell wall and cell membrane has already been reported (Liu et al., 2010). Thus, the nanomaterial-mediated transformation methods will provide great possibilities in developing transgenic plants. 5. Conclusions Climate change brings with it some daunting challenges. More food must be produced on less arable land than is available today. New agricultural technologies and farming practices must be developed and implemented. This chapter has attempted to address


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some of the strategies currently under development in the agricultural sciences. One way to achieve global food security requires the utilization of novel plant breeding strategies which will quickly find helpful traits that enable plants to thrive under adverse environmental conditions. Green technology will bring an extensive transformation of agriculture to increase production and improve quality in an equitable and sustainable manner without compromising the environment (Godfray et al., 2010). Biotechnology and nanotechnology will play a paramount role in these approaches. Revolutionary farming techniques, led by precision agriculture, will keep crop yields high while maintaining water, pesticide, and nitrogen inputs to a minimum. Key food crops have already been biofortified with micronutrients such as iron and vitamin A. With these and other strategies in place, the world will be better prepared to address the future challenges that will result from climate change and increasing population. References Beatty, P., & Good, A. (2011). Future prospects for cereals that fix nitrogen. Science, 333, 416–417. Beddington, J. (2010). Food security: Contributions from science to a new and greener revolution. Philosophical Transactions of the Royal Society B: Biological Sciences, 365, 61–71. Beebe, S., Gonzalez, A. V., & Rengifo, J. (2000). Research on trace minerals in the common bean. Food and Nutrition Bulletin, 21, 387–391. Bhatnagar-Mathur, P., Vadez, V., & Sharma, K. K. (2008). Transgenic approaches for abiotic stress tolerance in plants: Retrospect and prospects. Plant Cell Reports, 27, 411–424. Borrill, P., Connorton, J., Balk, J., Miller, T., Sanders, D., & Uauy, C. (2014). Biofortification of wheat grain with iron and zinc: Integrating novel genomic resources and knowledge from model crops. Frontiers Plant Sciences, 5, 1–8. Cañas, J. E., Long, M., Nations, S., Vadan, R., Dai, L., Luo, M., … Olszyk, D. (2008). Effects of functionalized and non-functionalized single-walled carbon nanotubes on root elongation of select crop species. Environmental Toxicology and Chemistry, 27, 1922–1931. Díaz de la Garza, R., Gregory, J. F., & Hanson, A. D. (2007). Folate biofortification of tomato fruit. Proceedings of the National Academy of Sciences, 104, 4218–4222. Diretto, G., Al-Babili, S., & Tavazza, R. (2007). Metabolic engineering of potato carotenoid content through tuber-specific overexpression of a bacterial mini-pathway. PLoS ONE, 2, e350. Foley, J. A., Ramankutty, N., Brauman, K. A., Cassidy, E. S., Gerber, J. S., Johnston, M., … West, P. C. (2011). Solutions for a cultivated planet. Nature, 478, 337–342. Galloway, J. N., Aber, J. D., Erisman, J. W., Seitzinger, S. P., Howarth, R. W., Cowling, E. B., & Cosby, B. J. (2003). The nitrogen cascade. BioScience, 53, 341–356. Galloway, J. N., Dentener, F. J., Capone, D. G., Boyer, E. W., Howarth, R. W., Seitzinger, S. P., … Holland, E. A. (2004). Nitrogen cycles: Past, present, and future. Biogeochemistry, 70, 153–226. Galloway, J. N., Townsend, A. R., Erisman, J, Bekunda, M., Cai, Z., Freney, J. R., … Sutton, M. A. (2008). Transformation of the nitrogen cycle: Recent trends, questions, and potential solutions. Science, 320, 889–892. Godfray, H. C. J., Beddington, J. R., Crute, I. R., Haddad, L., Lawrence, D., Muir, J. F., … Toulmin, C., 2010. Food security: The challenge of feeding 9 billion people. Science, 327, 812–818. Johnson, A. A. T., Kyriacou, B., Callahan, D. L., Carruthers, L., Stangoulis, J., & Lombi, E. (2011). Constitutive over expression of the OsNAS gene family reveals single-gene strategies for effective iron- and zinc-biofortification of rice endosperm. PLoS ONE, 6, e24476. Jun, L., Feng-Hua, W., Ling-ling, W., Su-yao, X., Chun-yi, T., Dong-ying, T., & Xuan-ming, L. (2008). Preparation of fluorescence starch-nanoparticle and its application as plant transgenic vehicle. Journal of Central South University of Technology, 15, 768–773. Khodakovskaya, M. V., de Silva, K., Nedosekin, D. A., Dervishi, E., Biris, A. S., Shashkov, E. V., … Zharov, V. P. (2011). Complex genetic, photothermal, and photoacoustic analysis of nanoparticle plant interactions. Proceedings of the National Academy of Sciences, 108, 1028–1033. Lin, D., & Xing, B. (2007). Phytotoxicity of nanoparticles: Inhibition of seed germination and root growth. Environmental Pollution, 150, 243–250.


14

S. Yashveer et al.

Liu, Q., Zhao, Y., Wan, Y., Zheng, J., Zhang, X., Wang, C., & Fang, X. (2010). Study of the inhibitory effect of water soluble fullerenes on plant growth at the cellular level. ACS Nano, 4, 5743–5748. Mccandless, L. 2011. Nanotechnology offers new insights to plant pathology. Retrieved from http://www.cals.cornell.edu/cals/public/comm/pubs/cals-news/cals-news Oldroyd, G. E. D., & Dixon, R. (2014). Biotechnological solutions to the nitrogen problem. Current Opinion in Biotechnology, 26, 19–24. Opara Linus, U. (2004). Emerging technological innovation triad for smart agriculture in the 21st century. Part 1. Prospects and impacts of nanotechnology in agriculture. Agricultural Engineering International: The CIGR Journal of Scientific Research & Development, Invited Overview. Retrieved from http://www.cigrjournal.org/index.php/Ejounral/ Ortiz-Monasterio, J. I., Palacios-Rojas, N., Meng, E., Pixley, K., Trethowan, R., & Peña, R. J. (2007). Enhancing the mineral and vitamin content of wheat and maize through plant breeding. Journal of Cereal Science, 46, 293–307. Paine, J. A., Shipton, C. A., Chaggar, S., Howells, R. M., Kennedy, M. J., Vernon, G., … Drake, R. (2005). Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nature Biotechnology, 23, 482–487. Pasupathy, K., Lin, S., Hu, Q., Luo, H., & Ke, P. C. (2008). Direct plant gene delivery with a poly(amidoamine) dendrimer. Biotechnology Journal, 3, 1078–1082. Pérez-de-Luque, A., & Rubiales, D. (2009). Nanotechnology for parasitic plant control. Pest Management Science, 65, 540–545. Remya, N., Saino, H. V., Baiju Nair, G., Maekawa, T., Yoshida, Y., & Kumar, D. S. (2010). Nanoparticulate material delivery to plants. Plant Science, 179, 154–163. Rockström, J., Steffen, W., Noone, K., Persson, Åsa, Chapin, F. S., Lambin, E. F., … Schellnhuber, H. J. (2009). A safe operating space for humanity. Nature, 461, 472–475. Sadanandom, A., & Napier, R. M. (2010). Biosensors in plants. Current Opinion in Plant Biology, 13, 736–743. Sautter, C., Poletti, S., Zhang, P., & Gruissem, W. (2006). Biofortification of essential nutritional compounds and trace elements in rice and cassava. Proceedings of the Nutrition Society, 65, 153–159. Sharon, M., Choudhary, A. K., & Kumar, R. (2010). Nanotechnology in agricultural diseases and food safety. Journal of Phytology, 2, 83–92. Somvanshi, V. S. (2009). Patenting drought tolerance in organisms. Recent Patents on DNA & Gene Sequences, 3, 16–25. Temme, K., Zhao, D., & Voigt, C. A. (2012). Refactoring the nitrogen fixation gene cluster from Klebsiella oxytoca. Proceedings of the National Academy of Sciences, 109, 7085–7090. Tester, M., & Langridge, P., 2010. Breeding technologies to increase crop production in a changing world. Science 327, 818–822. Torney, F., Trewyn, B., Lin, V. S. Y., & Wang, K. (2007). Mesoporous silica nanoparticles deliver DNA and chemicals into plants. Nature Nanotechnology, 2, 295–300. Welch, R. M., & Graham, R. D. (2004). Breeding for micronutrients in staple food crops from a human nutrition perspective. Journal of Experimental Botany, 55, 353–364. Ye, X., Al-Babili, S., Klöti, A., Zhang, J., Lucca, P., Beyer, P., & Potrykus, I. (2000). Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science, 287, 303–305.

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