日本稲と外国稲との交雑による育種の基礎的研究 : IV. F<SUB>2</SUB>における糯粳性の異常分離

Abstract

1. Continued from the previous report on the anomalous segregation of glutinous character in pollens and in xenia in F1 hybrids between Japanese and foreign varieties (MIZUSHIMA and KONDO, 1961) behaviors in segregation in their F2 population were described. 2. In eight of the 26 different F2 strains investigated which were originated from 7 Japanese X Japanese and I IndianXJapanese crosses the segregation took place normally, i.e., gl+gl:gl+gl :glgl 1 : 2 :1 (Table 1). The other 18 crosses showed abnormal ratios which could be classified into the following 5 different types according to the ratio gl+gl+ : gl+gl : glgl i ) 2 : 3 : 1-type' ?? ?? 10 crosses (Table 2) ii ) 4 : 5 : 1-type or 4 : 4 : 1-type ?? ?? crosses (Table 3) iii) O.76 : 1.74 : 1.OO-type ?? 2 crosses (Table 4) iv) 4 : 7 : 3-type ?? ?? crosses (Table 5) v) Undefined type ?? ?? cross (Table 6) 3. For the explanation of anomalous segregation ratios observed in xenia in F1 hybrids we assumed a) three different degrees of partial infunctionality of glutinous pollens, 25, 50 and 75 per cent, in such hybrids as to show a significant decrease in the number of glutinous endosperms and b) about 13 per cent infuhctionality of both non-glutinous pollens and ovules in hybrids showing sig'nificant decrease in the number of non-glutinous endosperms. The three of the above-mentioned 5 types, i), ii), and iv), can be explained as the results due to the cause a) and another one, iii), as that due to the cause b). The undefined type, v), is however, difflcult to explain. 4. The genetic mechanism causing the partial gametic infunctionality in F1 hybrids was discussed to the effect that it might be due to aco mplementary lethal action of two recessive genes, one of which being linked with gl-gene, or to deficiency of genes brought about by some unknown structural hybridity. 5. Behavior in segregation of C-gene was investigated, which was one of the two fundamentaL genes responsible for anthocyanin pigmentation in the rice plant body and had already been confirmed to be linked with gl-gene by other workers (Nagao and Takahashi, 1947). As was expected, anomalous mode of C-gene segregation was recognized in the present materials, presenting significant decrease in the number of gametes carrying one allel. 6. The recombination values between x and C and x and gl were calculated, here x being one of the complementary lethal genes linked with gl-gene. We obtained the values 0.323 fcr the fcrmer and O.392 for the latter.