Inheritance of bc1 Gene in Intersubspecific Hybrids of Rice (Oryza sativa L.)

Distorted segregation of the brittle culm-1 gene (bc1) on rice chromosome 3 was found with greatly increased or decreased frequency of bc1bc1 genotype in inter-subspecific hybrids,although the gene normally transmitted to its offspring following the Mendelian Law in intra-subspecific hybrids.In a combination of Kamairazu//Ketan Nangka/Kamairazu,an increased frequency of bc1bc1 in F_1,normal segregation in F_2,and increased and decreased frequency in a few F_3 and F_4 lines were observed.In a cross of IR36/Kamairazu,decreased frequency in F_2,both normal and decreased segregations in F_3 and F_4,and a few lines of increased ratio in F_4 were found.In F_2 of Ketan Nangka/IR36//Kamairazu,increased and decreased and normal segregations were all observed.There was no significant correlation between the frequency of bc1bc1 and pollen fertility.It implied that distorted segregation of bc1 was caused by selective fertilization of male gametes,which were governed by gametophyte genes of ga2,ga3 and ga14 on chromosome 3.