Fundamental studies on rice breeding through hybridization between Japanese and foreign varieties. : XIII.On the C-gl linkage relation in the progeny of the cross, Surjamkhi×Norin No.1

Abstract

The authors reported already that duplication and deficiency of C-locus which bore the gene responsible for the production of chromogen in the rice plant occurred in F2 of the cross, SurjamkhixNorin N0.1, and that it might be due to cryptic translo-cation or inversion (recombination value : ca. 50 per cent) of the gene locus (MIZUSHIMA and KONDO, 1959, '60). In the present paper reports the result of investigation of segregation in respect to C and gl genes in F2 of the cross, F5 (Surjamkhi x Norin No. 1) XHokkaimochi No. 1. The F5 plants used consisted of five having nonglutinous endosperm and colored glurme apiculus, and showed the effects of the dominant C- and glgene. One of them, however, was confirmed previously to have doubled C-loci, of genotype CBCB1APgl+ (KONDO and MIZUSHIMA, 1964 b). A is the gene which converts the chromogen into anthocyanin and P distributes anthocyanin to the site of apiculus in glume. Hokkaimochi No. I has glutinous endosperm and colorless apiculus whose genotype has been identified as C+A+pgl. In F2 CBCB1APgl+ X Hokkaimochi No. I a clear linkage relationship was observed between C- and gl-gene. However, it was difficult to determine which of the two C-genes, CB and CB1, was linked to gl. In the other three crosses the C-gl linkage was also confirmed and the recombination value was almost the same as reported by other workers (CHAO, 1928 ; NAGAO, 1951 ; JODON, 1957). From the linkage between C and gl observed in the present experiment we consider that duplication and deficiency of C-locus in the hybrids reported is not due to its cryptic translocation. However, the possibility of change in position of C-locus from one side of gl-locus to the other by inversion, keeping a linkage relationship between the two, still remains. This was discussed briefly from the tetrasomic segregation of C-gene already observed in the hybrids one of whose parent was Surjamkhi (KONDO and MIZUSHIIMA, 1964a) we concluded that the cause of duplication and deficiency is more probably atributable to a peculiar modes of conjugation of chromosomes bearing C-locus than tonversion as already suggested previously (KONDO and MIZUSHIMA, 1964 b).