The endosperm mutants, sugary and shrunken, which had been induced by chemical
mutagens, were considered to be each controlled by a single recessive gene
(Satoh and Omura 1981; Yano et al. 1984). But Yano et al. (1984) identified
three genes, su, shr-1 and shr-2, for these mutants. They also demonstrated
that su was located on chromosome 12 and shr-1 on chromosome 3.
The location of shr-2 was examined by using the trisomic series of Nipponbare. The mutant line with shr-2 (EM 34) showed a trisomic F\2\ ratio when crossed with the D-type trisomic (trisomy for Nishimura's chromosome 12). The F\3\ seed populations derived from F\2\ disomic plants fitted the 1 (segreg. for shr- 2):1(non-segreg.) ratio as expected (Table 1 Segregation pattern for shrunken-2 in F\2\ and F\3\ seeds of cross with trisomic type D). These experimental results suggest that gene shr-2 is located on chromosome 12.
Table 1. Segregation pattern for shrunken-2 in F\2\ and F\3\ seeds of cross
with trisomic type D
References
Satoh, H. and T. Omura, 1981. New endosperm mutations induced by chemical mutagenes in rice, Oryza sativa L.. Jpn. J. Breed. 31: 316-326.
Yano, M., Y. Isono, H. Satoh and T. Omura, 1984. Gene analysis of sugary and shrunken mutants of rice, Oryza sativa L.. Jpn. J. Breed. 34: 43-49.