Theoretical and Applied Genetics 39, t 7--20 (I 969)
Stamina pistilloida: A n e w M u t a t i o n Induced in Pea* L. M. MONTI 1 and M. DEVREUX ~ L a b o r a t o r y for Applications in Agriculture of the National Committee for Nuclear Energy, R o m e x, and Biology D e p a r t m e n t of E u r o p e a n Atomic E n e r g y Community, Bruxelles ~ Summary. After diethylsulphate treatment of seeds of the pea variety 'Parvus', a new floral mutation was isolated in the second generation. This mutation, named stamina pistilloida, is characterized by a partial fusion of the androecium with the gynoecium; the two marginal stamens of the staminal column are transformed in rudimentary carpels more or less differentiated according to ecoclimatic conditions. The genetic analysis has shown the monogenic and recessive behaviour of the mutation (gene proposed stp) and its linkage with the gene oh in the chromosome II.
Introduction In our experiments with physical and chemical mutagens (MoNTI, t968) several mutations have been induced, some of which resembling already known gene mutations. This note describes an induced mutation for a new floral a b n o r m a l i t y in pea. Material and Methods The M 1 branch progeny P 829c, coming from seed t r e a t m e n t with diethylsulphate in the fodder pea ' P a r v u s ' (MONTI and SCARASCIA-MUGNOZZA, t964), segregated in M~ for 2 plants with floral abnormalities in a total of t4 plants. The m u t a t i o n was crossed with the mother line ' P a r v u s ' in order to have segregation d a t a and also crossed with the line no. 85I from LAMPRECHT'S collection (BLIXT, 1963) in order to investigate its linkage relationship with other marker genes. Line no. 851 is characterized b y the presence of several recessive genes, of which only those reported below have been taken into account in the segregation analysis (in brackets: the linkage group): i (I) green cotyledons in the seeds; oh (II) reddish brown colour of testa of seeds; s (II) seeds sticking together; wb (II) little wax on the plant; k (II) reduced wings of the flowers; st (III) reduced stipules of the leaves; b (III) clariroseus flower colour; le (IV) short internodes; r (VII) wrinkled seeds; tl (VII) tendrils transformed into leaflets. The following percentages of recombination are known among some of those marker genes (LAMPRECHT, t961) : chromosome I I : s (9) wb; s (20) k; wb (t8) k; chromosome I I I : st (26) b; chromosome V I I : r (5) t/. * Contribution No. 187 from the Laboratorio per le Applicazioni in Agricoltura, C. N. E. N., S. Maria di Galeria, Roma, Italy and No. 406 from the Biology Department of European Atomic Energy Community.
The F 1 plants from both the crosses (with the mother line and with line 851) were grown in greenhouse and a meiotic analysis was pursued; the F 2 segregation analysis was performed in the field. A corrected chi square for disturbed segregations (MATHER, 1957) was used for detecting linkage and the crossing over values were calculated b y the product method using the tables of STEVENS (t939). D a t a on fertility, expressed as number of ovules and seeds per pod, were collected on 20 m u t a n t s and 20 normal plants grown in greenhouse. For an histological analysis of the m u t a n t , flowers from m u t a n t and normal plants were fixed in FAA, dehydrated in an alcohol xylol series, sectioned at t6 microns, and stained with ferric hematoxylin-fast green. Results The histological analysis shows that, in the normal flower, the androecium and the gynoecium separate from each other, first on the side of the free stamen and afterwards on the opposite side. In the m u t a n t flower, the gynoecium disjoins from the androecium on the opposite side of the free stamen and remains fused with the staminal column and precisely with both the marginal stamens (Fig. t - 5); the suture at the base of the carpel margins is often incomplete in the m u t a n t because of the fusion above mentioned (fig. 5,6). The two stamens fused with the carpel get thicker and thicker, separate themselves from the staminal column and present reproductive elements with various degrees of differentiation (Fig. 7 - - t 0 ) : in fact, those two stamens can show more or less differentiated r u d i m e n t a r y carpels (fig. t t , 12), without or with one or two normal campytotropous ovules outside (fig. 13, 14). The most differentiated carpels are like small ovaries but with free margins (Fig. i 5). The two pistilloid stamens dissociate from the carpel at different levels and above the carpellike tissue present r u d i m e n t a r y anthers with degenerate pollen grains (fig. 12, 14). Apparent normal stigma is present on the distal part of each of the pistilloid stamens (fig. 15).
t8
L.M. MONTI and M. DEVREUX:
Theoret. Appt. Genetics
Fig. 11-12, Transversal sections in a stp mutant flower Fig. 1I. One "pistilloid" stamen fused with the carpel Fig. 12. At a higher level, the "pistilloid" stamen with its rudimentary anther and degenerate pollen grains
Fig. t 3--14. Supernumerary ovules out of the carpel Macroscopically, the main differences between the m u t a n t and tile n o r m a l flowers are t h a t the two petals forming the keel are not fused b u t overlapping and t h a t , instead of the diadelphous condition, there are in the m u t a n t 8 n o r m a l s t a m e n s (7 connate, one free) and two pistilloid s t a m e n s c o n n a t e at their base with the s t a m i n a l column a n d with the n o r m a l unicarpellate pistil (fig. 16). On the ripe pods, the two pistilloid stamens remain as r u d i m e n t s on the ventral suture (fig. t7). F u r t h e r m o r e , it seems t h a t the env i r o n m e n t a l growing conditions influence the m u t a tion p h e n o t y p e . N o difference was f o u n d between the m u t a n t and the m o t h e r line ' P a r v u s ' as to n u m b e r of ovules per pod (5.85 4 - 0 . 1 3 for the m u t a n t against 5.92 4Fig. t--10. Flower transversal sections in control (left) and stp mutant (right).
Stamina pistilloida: A new Mutation Induced in Pea
Vol. 39, No. 1
t9
Fig. 17 A ripe pod of the stp m u t a n t : the two "pistilloid" stamens remain as rudiments on the ventral suture.
Crossing over (%) values of 31.3 + 2 . 7 a n d o f 8.8 ~ 1.4 were calculated respectively between st and b and between r and tl. The values found for s, wb and k are reported in table 1. As to the gene stp, linkage was ascertained between it and oh located in chromosome I I (chi square ~---36.45 ; P % 0.001), with a crossing over value of 16.95 + 4.65 (Table 1).
Fig. 15--16. The gynoecium of a flower and a young pod of the stp m u t a n t where the abnormalities of the mutation are clear
0.06 of 'Parvus') and number of seeds per pod (3.99 :k 0.36 and 4.22 • 0.18 respectively). The F 1 plants after backcross with ' P a r v u s ' were normal and had a good seed set ; no chromosome aberration was found at meiosis. In F2, on a total of 156 plants a segregation of 25.64% was found (chi square for 3:1 = 0.034; 0.75 ~ P ~ 0.90), showing a recessive and monogenic behaviour of the mutation. The symbol stp (stamina pistilloida) is proposed to design this mutation. For linkage studies, 500 seeds, coming from 6 F 1 plants after the cross between the m u t a n t line and the line 851 were sown; they gave 452 plants, 2t of which did not set seeds due to disease attack.
Discussion Pistillody of any of the floral organs is a very frequent floral abnormality in higher plants (MEYER, 1966). More recently, mutations showing conversion of some stamens to pistils, have been described in different species of Gramineae (KIHARA, 1951; Moll a n d NILAN, 1953; BARABAS, t962; BATHIA and SWA~IINATHAN, 1963; FEJER, 1966); MEYER and BUFFET (t962) have found external ovules on carpel-like tissue at the top of the androecium in Gossypium interspecific hybrids. In P i s u m , cases of pistillody of sepals (LAxTON, 1866; LAMPRECHT, t934; GOTTSCHALK, 1961) and leaves (MARXand MISI~ANEC,1964) are known. Also in pea, GOTTSCHALK (1961) has described an induced m u t a n t in which extra carpels are formed from anther and calyx tissue. Tile abnormality reported in this paper represents the first case of a clear conversion of some stamens to pistillike structures. The main effect of the mutation seems to be the partial fusion of the androecium with the gynoecium.
Table t. F 2 segregation and recombination values (%) for the markers oh, s, wb, k of the chromosome I I and the mutant gene stp number of plants Factors Xx
chi-squared
Phase * Phenotype Yy
XY
Xy
xY
xy
Total
Oh oh
Stp stp
~R
2t8
84
t26
3
431
S s Wb wb K k Oh oh Oh oh Oh oh S s Ss Wb wb
Stp stp Sip stp Stp stp Ss Wb wb /f k Wb wb Kk K k
R R R C C C C C C
303 270 267 272 240 227 332 3t5 306
80 79 72 30 62 75 51 68 43
41 82 85 ttt 94 98 2 10 33
7 21 28 18 35 31 46 38 70
431 452 452 431 431 431 431 43t 452
* R = Repulsion; C = Coupling ** The chi square for disturbed segregations was used (MATItER, t 957)
Recombination value Segrega- Segrega- Joint t i o n o f x t i o n o f y Segregation** %
5.59 44.18 t.18 o.o0 5.59 5.59 5.59 44.18 44.18 1.18
5.32 5.32 f.99 t .99 44.18 t.43 O.O4 t.43 0.04 0.00
36.45 1.o5 0.23 0.62 t.47 2.26 o.o3 166.53 86.74 131.31
16.95 4- 4.65
6.68 -4- 1.25 17.62 i 2.05 t8.8t ~ 2.08
20
L.M. MONTI and M. DEVREUX: Stamina pistilloida: A new Mutation Induced in Pea
According to HESLOP-HARRISON (1957), the g r o w t h of s t a m e n a n d pistil p r i m o r d i a is g o v e r n e d b y the a u x i n level a n d ,,the c o n c e n t r a t i o n p r o m o t i n g m a x i m a l s t a m e n g r o w t h is lower t h a n t h a t p r o m o t i n g m a x i m a l pistil g r o w t h " . The t r a n s i t i o n forms of s t a m i no-carpels of our m u t a n t could p r o b a b l y be due to a n a l t e r a t i o n of the r e l a t i v e c o n c e n t r a t i o n of a u x i n s p r e s e n t in t h e flower p r i m o r d i u m a n d the effect of the ec0climatic c o n d i t i o n s in the m a n i f e s t a t i o n of this m u t a t i o n could also be e x p l a i n e d w i t h the influence t h a t those c o n d i t i o n s h a v e on the a u x i n s available at the d i f f e r e n t i a t i n g apex. The m u t a t i o n b e h a v e s as a simple recessive Mendelian character, a n d it does n o t seem to be due to, or a c c o m p a n i e d b y c h r o m o s o m e a b e r r a t i o n . The q u i t e good c o r r e s p o n d a n c e b e t w e e n the crossing over f o u n d b y us a n d those r e p o r t e d b y LAMPRECHT (1961) a n d BLIXT (1965), confirms t h a t no t r a n s l o c a t i o n is pres e n t in our m a t e r i a l , at least in the a n a l y z e d chromosomie regions. The genetic analysis has s h o w n t h a t the gene responsible for the m u t a t i o n stamina pistilloida is located in c h r o m o s o m e I I at a d i s t a n c e of a b o u t 17% of crossing over from the locus oh. F u r t h e r studies are n e e d e d for more exact localization of the m u t a t i o n .
Acknowledgement The authors are greatly indebted to Prof. F. D'AMATO and Prof. G . T . SCARASCIA-MUGNOZZA for the critical review of the manuscript and to Mr. P. VITALE and Mr. L. ANSELMI for their precious technical assistance.
Zusammenfassung Nach B e h a n d l u n g y o n S a m e n der E r b s e n s o r t e ' P a r v u s ' m i t Di~ithylsulfat wurde in der 2. G e n e r a t i o n eine neue B l t i t e n m u t a t i o n ausgelesen. Diese Mutation, die stamina pistilloida b e n a n n t wurde, ist d u r c h eine teilweise V e r s c h m e l z u n g des A n d r o e z e u m s m i t d e m G y n a e z e u m g e k e n n z e i c h n e t . Die b e i d e n margin a l e n Staubbl~itter der S t a u b b l a t t - R 6 h r e sind zu rudiment~iren K a r p e l l e n u m g e b i l d e t , die e n t s p r e c h e n d den 6 k o k l i m a t i s c h e n Verh~iltnissen m e h r oder weniger
Theoret. Appl. Genetics
differenziert sind. Die genetische A n a l y s e ergab, d a b sich die M u t a t i o n ( G e n s y m b o l stp) m o n o g e n u n d rezessiv verh~tlt u n d m i t d e m Gen oh i m Chromosom I I gekoppelt ist.
Literature I. BARABAS,F, : Observation on sex differentiation in Sorghum by use of induced male-sterile mutants. Nature 195, 257--259 (1962). -- 2. BATHIA, C.R., and M.S. SWAMINATHAN:An induced multiple carpel mutation in bread wheat. Genetica 43, 58-- 65 (1963). -- 3. BLIXT, S. : A presentation of the Lamprechtian Pisum-material. Report from Weibullsholm P l a n t Breeding Institution (1963). -- 4. BLIXT, S. : Linkage studies in Pisum I linkage of the genes Chi 2 Chi 3 and Chi 4 causing chlorophyll deficiency. Agri Hort. Genet. 22, 26--42 (1965). -- 5. FEJER, S. O. : A floral mutation in Lolium perenne. Canad. Jour. Genet. and Cyt. 8, 115--121 (1966). -- 6. GOTTSCHALK, W.: l)ber die zei~liche Aufeinanderfolge bestimmter Gestaltungsprozesse bei der Ausdifferenzierung yon Vegetationskegeln zu Bliiten. Naturwissenschaften 49, 59 (1961). -- 7. HESLoP-HARRISON, J.: The experimental modification of sex expression in flowering plants. Biol. Rev. (Cambridge Phil. Soc.) 32, 38--90 (1957). --8. KIHARA, H. : Substitution of nucleus and its effects on Genome Manifestation. Cytologia 16, 177-- 193 (1951). -- 9. LAMPRECHT, H.: Das Gene Uni und seine Koppelung mit anderen Genen bei Pisum. Hereditas 18, 269--296 (1934). -- t0. LAMPRECHL H.: Die Genenkarte von Pisum bei normaler Struktur der Chromosomen. Agri Hort. Genet. 19, 360--401 (1961). -- 11. LAXTON: Double-blossomed peas. Gard. Chron., p. 901 (1866). -12. MARX, G. A., and W. MISHANEC: The ,,Spontaneous" Formation of Rudimentary Carpels on Leaf Tissue. Journal paper no. 1938 (N. Y. State Agricultural Exp. Station), 40--41 (1964). -- 13. MATHER, K.: The measurement of linkage in heredity. London: Methuen and Co. Ltd. 1957. -- 14. MEYER, V. G.: Flower abnormalities. The Botanical Review 3 a, 165 -- 218 (| 966). -- 15. MEYER, V. G., and M. BUFFET: Cytoplasmic effects on externalovule production in cotton. J. Hered. 43, 251--253 (1962). -- t6. MOH, C. C., and R. A. NILAN: Multi-ovary in barley. A m u t a n t induced by atomic bomb irradiation. J. Heredity 44, t83--188 (1953). -- 17. MONTI, L.M.: Mutations in peas induced by diethylsulphate and X-rays. Mutation Res. 5, 187--191 (1968). -- 18. MONTI, L. M., and G . T . SCARASCIAMUGXOZZA: Effetti mutageni del dietilsolfato nel pisello. Atti Assoc. Genet. Ital. 9, 115 --125 (1964). -- 19. STEVENS, W . L . : Tables of the recombination fraction estimated from the product ratio. J. Genetics 39, 1 7 t - 180 (1939).
L. M. MONTI Laboratory for Applications in Agriculture of the National Committee for Nuclear Energy, Rome, I t a l y
M. D E V R E U X Biology Department of European Atomic Energy Community, Bruxelles, Belgium.
Stamina pistilloida: A n e w M u t a t i o n Induced in Pea* L. M. MONTI 1 and M. DEVREUX ~ L a b o r a t o r y for Applications in Agriculture of the National Committee for Nuclear Energy, R o m e x, and Biology D e p a r t m e n t of E u r o p e a n Atomic E n e r g y Community, Bruxelles ~ Summary. After diethylsulphate treatment of seeds of the pea variety 'Parvus', a new floral mutation was isolated in the second generation. This mutation, named stamina pistilloida, is characterized by a partial fusion of the androecium with the gynoecium; the two marginal stamens of the staminal column are transformed in rudimentary carpels more or less differentiated according to ecoclimatic conditions. The genetic analysis has shown the monogenic and recessive behaviour of the mutation (gene proposed stp) and its linkage with the gene oh in the chromosome II.
Introduction In our experiments with physical and chemical mutagens (MoNTI, t968) several mutations have been induced, some of which resembling already known gene mutations. This note describes an induced mutation for a new floral a b n o r m a l i t y in pea. Material and Methods The M 1 branch progeny P 829c, coming from seed t r e a t m e n t with diethylsulphate in the fodder pea ' P a r v u s ' (MONTI and SCARASCIA-MUGNOZZA, t964), segregated in M~ for 2 plants with floral abnormalities in a total of t4 plants. The m u t a t i o n was crossed with the mother line ' P a r v u s ' in order to have segregation d a t a and also crossed with the line no. 85I from LAMPRECHT'S collection (BLIXT, 1963) in order to investigate its linkage relationship with other marker genes. Line no. 851 is characterized b y the presence of several recessive genes, of which only those reported below have been taken into account in the segregation analysis (in brackets: the linkage group): i (I) green cotyledons in the seeds; oh (II) reddish brown colour of testa of seeds; s (II) seeds sticking together; wb (II) little wax on the plant; k (II) reduced wings of the flowers; st (III) reduced stipules of the leaves; b (III) clariroseus flower colour; le (IV) short internodes; r (VII) wrinkled seeds; tl (VII) tendrils transformed into leaflets. The following percentages of recombination are known among some of those marker genes (LAMPRECHT, t961) : chromosome I I : s (9) wb; s (20) k; wb (t8) k; chromosome I I I : st (26) b; chromosome V I I : r (5) t/. * Contribution No. 187 from the Laboratorio per le Applicazioni in Agricoltura, C. N. E. N., S. Maria di Galeria, Roma, Italy and No. 406 from the Biology Department of European Atomic Energy Community.
The F 1 plants from both the crosses (with the mother line and with line 851) were grown in greenhouse and a meiotic analysis was pursued; the F 2 segregation analysis was performed in the field. A corrected chi square for disturbed segregations (MATHER, 1957) was used for detecting linkage and the crossing over values were calculated b y the product method using the tables of STEVENS (t939). D a t a on fertility, expressed as number of ovules and seeds per pod, were collected on 20 m u t a n t s and 20 normal plants grown in greenhouse. For an histological analysis of the m u t a n t , flowers from m u t a n t and normal plants were fixed in FAA, dehydrated in an alcohol xylol series, sectioned at t6 microns, and stained with ferric hematoxylin-fast green. Results The histological analysis shows that, in the normal flower, the androecium and the gynoecium separate from each other, first on the side of the free stamen and afterwards on the opposite side. In the m u t a n t flower, the gynoecium disjoins from the androecium on the opposite side of the free stamen and remains fused with the staminal column and precisely with both the marginal stamens (Fig. t - 5); the suture at the base of the carpel margins is often incomplete in the m u t a n t because of the fusion above mentioned (fig. 5,6). The two stamens fused with the carpel get thicker and thicker, separate themselves from the staminal column and present reproductive elements with various degrees of differentiation (Fig. 7 - - t 0 ) : in fact, those two stamens can show more or less differentiated r u d i m e n t a r y carpels (fig. t t , 12), without or with one or two normal campytotropous ovules outside (fig. 13, 14). The most differentiated carpels are like small ovaries but with free margins (Fig. i 5). The two pistilloid stamens dissociate from the carpel at different levels and above the carpellike tissue present r u d i m e n t a r y anthers with degenerate pollen grains (fig. 12, 14). Apparent normal stigma is present on the distal part of each of the pistilloid stamens (fig. 15).
t8
L.M. MONTI and M. DEVREUX:
Theoret. Appt. Genetics
Fig. 11-12, Transversal sections in a stp mutant flower Fig. 1I. One "pistilloid" stamen fused with the carpel Fig. 12. At a higher level, the "pistilloid" stamen with its rudimentary anther and degenerate pollen grains
Fig. t 3--14. Supernumerary ovules out of the carpel Macroscopically, the main differences between the m u t a n t and tile n o r m a l flowers are t h a t the two petals forming the keel are not fused b u t overlapping and t h a t , instead of the diadelphous condition, there are in the m u t a n t 8 n o r m a l s t a m e n s (7 connate, one free) and two pistilloid s t a m e n s c o n n a t e at their base with the s t a m i n a l column a n d with the n o r m a l unicarpellate pistil (fig. 16). On the ripe pods, the two pistilloid stamens remain as r u d i m e n t s on the ventral suture (fig. t7). F u r t h e r m o r e , it seems t h a t the env i r o n m e n t a l growing conditions influence the m u t a tion p h e n o t y p e . N o difference was f o u n d between the m u t a n t and the m o t h e r line ' P a r v u s ' as to n u m b e r of ovules per pod (5.85 4 - 0 . 1 3 for the m u t a n t against 5.92 4Fig. t--10. Flower transversal sections in control (left) and stp mutant (right).
Stamina pistilloida: A new Mutation Induced in Pea
Vol. 39, No. 1
t9
Fig. 17 A ripe pod of the stp m u t a n t : the two "pistilloid" stamens remain as rudiments on the ventral suture.
Crossing over (%) values of 31.3 + 2 . 7 a n d o f 8.8 ~ 1.4 were calculated respectively between st and b and between r and tl. The values found for s, wb and k are reported in table 1. As to the gene stp, linkage was ascertained between it and oh located in chromosome I I (chi square ~---36.45 ; P % 0.001), with a crossing over value of 16.95 + 4.65 (Table 1).
Fig. 15--16. The gynoecium of a flower and a young pod of the stp m u t a n t where the abnormalities of the mutation are clear
0.06 of 'Parvus') and number of seeds per pod (3.99 :k 0.36 and 4.22 • 0.18 respectively). The F 1 plants after backcross with ' P a r v u s ' were normal and had a good seed set ; no chromosome aberration was found at meiosis. In F2, on a total of 156 plants a segregation of 25.64% was found (chi square for 3:1 = 0.034; 0.75 ~ P ~ 0.90), showing a recessive and monogenic behaviour of the mutation. The symbol stp (stamina pistilloida) is proposed to design this mutation. For linkage studies, 500 seeds, coming from 6 F 1 plants after the cross between the m u t a n t line and the line 851 were sown; they gave 452 plants, 2t of which did not set seeds due to disease attack.
Discussion Pistillody of any of the floral organs is a very frequent floral abnormality in higher plants (MEYER, 1966). More recently, mutations showing conversion of some stamens to pistils, have been described in different species of Gramineae (KIHARA, 1951; Moll a n d NILAN, 1953; BARABAS, t962; BATHIA and SWA~IINATHAN, 1963; FEJER, 1966); MEYER and BUFFET (t962) have found external ovules on carpel-like tissue at the top of the androecium in Gossypium interspecific hybrids. In P i s u m , cases of pistillody of sepals (LAxTON, 1866; LAMPRECHT, t934; GOTTSCHALK, 1961) and leaves (MARXand MISI~ANEC,1964) are known. Also in pea, GOTTSCHALK (1961) has described an induced m u t a n t in which extra carpels are formed from anther and calyx tissue. Tile abnormality reported in this paper represents the first case of a clear conversion of some stamens to pistillike structures. The main effect of the mutation seems to be the partial fusion of the androecium with the gynoecium.
Table t. F 2 segregation and recombination values (%) for the markers oh, s, wb, k of the chromosome I I and the mutant gene stp number of plants Factors Xx
chi-squared
Phase * Phenotype Yy
XY
Xy
xY
xy
Total
Oh oh
Stp stp
~R
2t8
84
t26
3
431
S s Wb wb K k Oh oh Oh oh Oh oh S s Ss Wb wb
Stp stp Sip stp Stp stp Ss Wb wb /f k Wb wb Kk K k
R R R C C C C C C
303 270 267 272 240 227 332 3t5 306
80 79 72 30 62 75 51 68 43
41 82 85 ttt 94 98 2 10 33
7 21 28 18 35 31 46 38 70
431 452 452 431 431 431 431 43t 452
* R = Repulsion; C = Coupling ** The chi square for disturbed segregations was used (MATItER, t 957)
Recombination value Segrega- Segrega- Joint t i o n o f x t i o n o f y Segregation** %
5.59 44.18 t.18 o.o0 5.59 5.59 5.59 44.18 44.18 1.18
5.32 5.32 f.99 t .99 44.18 t.43 O.O4 t.43 0.04 0.00
36.45 1.o5 0.23 0.62 t.47 2.26 o.o3 166.53 86.74 131.31
16.95 4- 4.65
6.68 -4- 1.25 17.62 i 2.05 t8.8t ~ 2.08
20
L.M. MONTI and M. DEVREUX: Stamina pistilloida: A new Mutation Induced in Pea
According to HESLOP-HARRISON (1957), the g r o w t h of s t a m e n a n d pistil p r i m o r d i a is g o v e r n e d b y the a u x i n level a n d ,,the c o n c e n t r a t i o n p r o m o t i n g m a x i m a l s t a m e n g r o w t h is lower t h a n t h a t p r o m o t i n g m a x i m a l pistil g r o w t h " . The t r a n s i t i o n forms of s t a m i no-carpels of our m u t a n t could p r o b a b l y be due to a n a l t e r a t i o n of the r e l a t i v e c o n c e n t r a t i o n of a u x i n s p r e s e n t in t h e flower p r i m o r d i u m a n d the effect of the ec0climatic c o n d i t i o n s in the m a n i f e s t a t i o n of this m u t a t i o n could also be e x p l a i n e d w i t h the influence t h a t those c o n d i t i o n s h a v e on the a u x i n s available at the d i f f e r e n t i a t i n g apex. The m u t a t i o n b e h a v e s as a simple recessive Mendelian character, a n d it does n o t seem to be due to, or a c c o m p a n i e d b y c h r o m o s o m e a b e r r a t i o n . The q u i t e good c o r r e s p o n d a n c e b e t w e e n the crossing over f o u n d b y us a n d those r e p o r t e d b y LAMPRECHT (1961) a n d BLIXT (1965), confirms t h a t no t r a n s l o c a t i o n is pres e n t in our m a t e r i a l , at least in the a n a l y z e d chromosomie regions. The genetic analysis has s h o w n t h a t the gene responsible for the m u t a t i o n stamina pistilloida is located in c h r o m o s o m e I I at a d i s t a n c e of a b o u t 17% of crossing over from the locus oh. F u r t h e r studies are n e e d e d for more exact localization of the m u t a t i o n .
Acknowledgement The authors are greatly indebted to Prof. F. D'AMATO and Prof. G . T . SCARASCIA-MUGNOZZA for the critical review of the manuscript and to Mr. P. VITALE and Mr. L. ANSELMI for their precious technical assistance.
Zusammenfassung Nach B e h a n d l u n g y o n S a m e n der E r b s e n s o r t e ' P a r v u s ' m i t Di~ithylsulfat wurde in der 2. G e n e r a t i o n eine neue B l t i t e n m u t a t i o n ausgelesen. Diese Mutation, die stamina pistilloida b e n a n n t wurde, ist d u r c h eine teilweise V e r s c h m e l z u n g des A n d r o e z e u m s m i t d e m G y n a e z e u m g e k e n n z e i c h n e t . Die b e i d e n margin a l e n Staubbl~itter der S t a u b b l a t t - R 6 h r e sind zu rudiment~iren K a r p e l l e n u m g e b i l d e t , die e n t s p r e c h e n d den 6 k o k l i m a t i s c h e n Verh~iltnissen m e h r oder weniger
Theoret. Appl. Genetics
differenziert sind. Die genetische A n a l y s e ergab, d a b sich die M u t a t i o n ( G e n s y m b o l stp) m o n o g e n u n d rezessiv verh~tlt u n d m i t d e m Gen oh i m Chromosom I I gekoppelt ist.
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L. M. MONTI Laboratory for Applications in Agriculture of the National Committee for Nuclear Energy, Rome, I t a l y
M. D E V R E U X Biology Department of European Atomic Energy Community, Bruxelles, Belgium.
