同源四倍体水稻亚种间杂种F1具有强大生物学优势,花粉不育是其优势利用主要障碍之一.已有研究表明籼粳杂种花粉不育基因Sa、Sb和Sc座位互作是导致其花粉不育的主要遗传原因,每个座位籼型基因(ii)与粳型基因(jj)杂合均可产生互作,对F1花粉败育产生不同效应;多个座位同时互作,花粉败育呈上位性效应。本项目拟利用同源四倍体水稻近等基因系组配花粉不育基因不同互作类型杂种F1，以不互作的杂种F1作为对照，一是对不同座位互作类型杂种F1花粉发育过程的细胞学、基因表达谱差异、与减数分裂染色体行为有关基因表达差异等进行研究，以弄清互作是如何通过影响花粉发育基因表达而使杂种F1花粉出现不同败育；二是通过多座位同时互作与单座位互作比较研究,弄清前者是如何加重基因异常表达而使花粉败育率呈现上位性.研究结果有望弄清不同座位互作引起杂种F1花粉败育效应差异以及多基因互作上位性的分子机理,为克服不育性提供理论基础

Autotetraploid rice is a special genetic material and its intersubspecific hybrids have high potential to increase the rice yield, but it has major drawback of low seed set. Pollen abortion was one of most important reasons for low seed of the autotetraploid intersubspecific hybrids. In our previous research, it was found that pollen sterility loci (Sa, Sb and Sc) interactions are main genetic reason for pollen sterility of autotetraploid hybrids. Heterozygous genotype (ij) at each locus i.e., indica genotype (ii) and japonica genotype (jj), cause pollen sterility due to interaction between i and j alleles. The extent of pollen sterility is varied at each locus, while multi allelic interactions (two or three loci) result in very low pollen fertility in autotetraploid intersubspecific hybrids. So far, little information is available on the molecular mechanism of pollen sterility loci interaction in autotetraploid rice. In this project, we will make several combinations with different pollen sterility loci interactions by crossing with different pollen sterility iso-geneic lines, as well as the control combinations (without pollen sterility gene interaction) at these three pollen sterility loci using autotetraploid rice lines harboring Sa-n, Sb-n and Sc-n genes crossed with iso-geneic lines. The cytological insights, gene expression in whole genome and the expression of genes associated with pollen development in meiosis will be studied using above mentioned hybrids. From these observations, we'll be able to understand the molecular mechanism lie underneath the pollen sterility loci interaction i.e., how pollen genes interactions affect the genes expression during pollen development in autotetraploid intersubspecific hybrids and how it cause different degrees of pollen abortion. Moreover, we will be able to know that how multi pollen genes interactions affect the genes expression more bigly than single gene interaction, and how it results in very low pollen fertility of intersubspecific hybrids. These results will be very helpful for overcoming the sterility of autotetraploid intersubspecific hybrids and promote them for commercial application.