Bougerol, B.

Pham, Jean-Louis

Horizon / Pleins textes

W .  
Iyu 
as a natural group. Whcn the chloroplast DNA KFLP data previous1 
recognition of the Oryza section (O. sativa, O. latifolia and O. col 
the study of Dally (1988). I t  appeared that O. colli 
Ricc Genetics Newsletter Vol. O 
- 
The seven genera Ziranìu, Chikusìchloa, R amophilu, Hygroryra, 
Australia, does not favor the 
tribe because the closest relative (as 
a is Chikusìchloa which is endemic in 
re likely migrated from South-East Asia to 
tered together. The case of Potamophila, e 
origin of the pattern of distri 
read in the distance matrix) of 
Asia. A common Asian a 
Australia. Similarly, var’ 
Eurasia, the lates 
DNA RFLPs an 
eing studied at  the level of nuclear and mitochondrial 
Reference / , - I  
. D. and S. A. Renvoiza, 1986. Genera Graminum. Kew Bulletin additional series 
lyse cladistique de :mutations de l’ADN chloroplastique et phylogénie des 
Uryzn du genre Oryza). Coll. Etudes et Thèses. ORSTOM, Paris. 153 p. 
Nei, M., 1987. Molecular Evolutionary Genetics. Columbia Univ. Press, N. Y. 512 p. 1 
Second. G., 1985. Geographic origins, genetic diversity and the molecular clock hypothesis in 
the Oryzeae. In Genetic Differentiation and Dispersal in Plants. P. Jacquard et al. (eds.) 
NATO AS1 Series, Vol. G5, Springer-Verlag, Berlin Heidelberg. * 
IV. Segregation distortion 
15. Abnormal segregation patterns in crosses between Oryza sativa and O. 
glaberrima 
Jean-Louis PHAM and Bruno BOUGEROL 
Laboratoire d’Amelioration des Plantes, Centre ORSTOM d’Adiopodoume, BP V51, Abidjan, 
Cote d’Ivoire 
Four progenies of crosses between the two cultivated rice species were obtained 
by pollinating a common Oryza glaberrimalo. sativa F, hybrid with four different 
O. sativa cultivars. We present here the results on the development of these pro- 
genies arid on the segregations scored at  6 isozynie loci. 
The five parental varieties were: WO75 (O. glaberrinia, Guinea-Bissau), ES70-6 
(juporrica, Taiiz:inin), YS309 and YS-FS-I (japonica, Guinea), and SS404 (irrrlica, 
Senegal). WO25 was provided by the National Institute of Genetics (Mishima, 
ORSTOM Fonds Documentaire 1 
Reseqrcli Notes S I  
Japan) while O. sativu cultivars were obtained from ORSTOM collection. The 4 
crosses studied are presented i n  Table 1. The FI hybrid used as female parent 
W0251ES70-6 being coninion, the 4 crosses are designated as//ES70-6,//SS404,// 
YS45-I and lIYS309, respectively. 
The seeds were dehulled, disinfected, rinsed i n  water and then sown i n  petri 
dishes with nutritive solution. After 10 days, seedlings were planted in pots. 
Plants were grown in glasshouse. Electrophoresis procedures used are described 
by Second (1 982) and de Kochko (1 987). 
Approximately 40% of the plants were lost during cultivation (Table 1). 
The first level of loss was observed a t  seed germination. All progenies showed a 
similar rate of non-germinated caryopses (<30%),  which was about the same as 
for FI seeds of W0251ES70-6. The second level of losses occurred a t  seedling 
stage, where significant differences appeared between the progenies. More than 
50% seedlings of the crossllES70-6 died. 
Table 1. Development of plants in four glaberrimalsarival/satil,a backcrosses 
No. of sceds No. of No. of Total 
inviable adult percent 
seedlings plants of loss Cross Sown Non-germi- 
WOZS/ES70-6//ES70-6 35 16(145/0) 16(53%) 14 60% 
If If //ss404 46 4 (  9%) S(19%’0) 34 26 
II If ]]YS309 12 ’ 2(170/0) 1(10%) 9 25 
II n lIYss5-1 27 ’ 3(1296) 7 (29%) 17 37 
Table 2 presents the results for segregation of isozyme loci. Note that we 
have observed the segregations of the female gametes of the, FI hybrid W025J 
ES70-6. Four of the 20 observed segregations deviated (at 5 %  significance level) 
from the 1:l Mendelian ratio. The Est-:! locus was subject to distortion in the 
crosses//SS404 and l/ES70-6. Sdh-1 segregation was abnormal in the cross / /YS309. 
In these three cases, an excess of the O. glaberrinza allele was observed. On the 
other hand, a deficiency of the O. glaberrinra allele appeared a t  the Est-8 locus in 
the cross //ES70-6. 
Sano et al. (1979) proposed the “one-locus sporogametophytic interaction” 
model to account for the sterility of FI hybrids between the two cultivated species 
(Le., parents O. sativa and O. glaberrima are respectiveIy assumed to have Sasa 
and SS; the presence of the S allele in the maternal tissue leads to sterility of 
gametes Su). This model explains the distortion observed for Est-2, because 
marker genes linked to the sterility gene will be subject to distortion. Further, 
because of the chromosomal location of locus Est-1 and because the O. glaberrima 
parent WO15 was uscd by’Sano et al. (1979), i t  is likely that the sterility gene 
involved i n  our experintents is the sanie ;IS Sa-1 :ind S-1 dcsigntited by Sato et íil. 
(1 987). 
! 
8 
1 
. .  
I. 
81 Rico Geuctics Newsletter Vol. 6 
I 
Table 2. Segregation ratios observed at  isozyme loci in four cross progenies 
and test of their conformity to Mendelian I :  1 ratio 
~~~ 
IIES70-6 /ISS404 //YS309 llYS45-L 
LOCUSa 
G S Test(B) G S Test(G) G S Test(B) G S Test(B) 
Cat-I 10 4 ns 17 15 ns 7 2 ns 8 7 ns 
Est-1 7 7 ns I I  5 ns 
Est-2 I2 2 ** 27 5 *** 
Est-8 3 I I  * 17 16 ns 6 3 ns 8 9 ns 
Pgi-I 6 8 ns 20 14 ns 5 4 ns 7 10 ns 
Sdk-I I 7 ns 18 16 ns 9 o ** 11 6 ns 
a: Synibols follow those proposed in RGN 3. p. 15-17. 
G: Plants with the allele from U .  gluberrima parent, W025. 
S :  Plants with the allele from O. sativa parent, ES70-6. 
Test(B): Binomial test (Sokal and Rohlf 1981, p. 78). 
Test(G): G-test (Sokal and Rohlf 1981, p. 706). 
ns: Not significant; * P<0.05; ** P<O.Ol; *** P<O.OOI.  
The “one-locus sporogainetophytic interaction” model cannot explain the 
observations at  the loci Est-8 and Sdz-1 because opposite results were observed in 
different crosses. This nieans that the genotype of the male O. sativa parents has 
to be considered, in addition of those of WO25 and ES70-6. The differential rates 
of loss during the cultivation could explain the deviation a t  Es t4  in the cross 
//ES70-6. The hypothesis of an early differential zygotic selection, involving an 
albumen-embryo interaction, seems necessary to account for the distortion of 
Sdh-l. This was suggested by Gadish and Zamir (1987) in an  interspecific cross 
between Lycopersìcum esculentum and L. penneli. 
References 
Gadish, I. and D. Zamir, 1987. Differential zygotic abortion in an interspecific Ljcopersicon 
cross. Genome 29: 156-159. 
Kochko. A. de, 1987. Isozymic variability of traditional rice (Oryza sativa L.) in Africa. Theor. 
Appl. Genet. 73: 675-682. 
Sano, Y., Y. E. Chu and H. I. Oka, 1979. Genetic studies of speciation in cultivated rice, 1. 
Genic analysis for the F I  sterility between O. sativa L. and O. gluberrima Steud. Jpn. J. 
Genet. 54: 121-132. 
Sato, Y.-I., Y. Sano and M. Nakagahra, 1987. Gene symbols for gametic effect, sterility and 
weakness. RGN 4: 46-56. 
Second, G., 1982. Origin of the genetic diversity of cultivated rice (Oryza ssp.): Study of the 
polymorphism scored at  40 isozyme loci. Jpn. J. Genet. 57: 25-57. 
Sokal, R. R. and F. J. Rohlf, 1981. Biometry (2nd ed.). Freeman, San Francisco. 859 pp. 
J 


Abnormal segregation patterns in crosses between Oryza sativa and O. glaberrima

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