Identification Of Two Novel Recessive Interaction Gene Regulating Panicle And Leaf Organization In Rice (Oryza Sativa L.)

Recent breakthrough advances in the theories and techniques of genomics and function genomics research, together with developments in gene identification, molecular-marker assistant selection, transgenic technique, facilitate the development of molecular breeding. The scientists bring forward the technology system of variety molecular design breeding to overcome the disadvantage of tradition breeding technology. The understanding to key gene and/or QTL function was the core for variety molecular design. The panicle and leaf organizations were important agriculture traits, and were also significant elements for variety molecular design. This study analyzed the progenies from the cross between indica (Oryza sativa indica L.) Guanghui 998 and the japonica (Oryza sativa japonica L.) Wuyujing 3, and identified two interaction genes regulating panicle and leaf organization traits. Results were as following:1. According to the phenotype separation ratio of F2, F3 and BC1F2 populations, the plant traits with small panicle and narrow leaf from the cross progenies between Guanghui 998 and Wuyujing 3 were affirmed to be regulated by two recessive interaction genes, which derived from two parents, respectively.2. The plants with small panicle and narrow leaf from F2 population crossed with parents Guanghui 998 and Wuyujing 3, respectively. Through the segregation of backcross F2 difference populations, bulked segregant analysis (BSA) and co-segregation analysis were used to screen SSR markers linked with the two interaction genes, the recessive interaction gene from Wuyujing 3 was located to the region between markers RM176 and RM345 on chromosome 6 about 2.2 cM, and named spnl6 (small panicle and narrow leaf 6). The allelic from Guanghui 998, named spnl7, was mapped to the region between markers RM3767 and RM5499 on chromosome 7 about 0.5 cM.3. Increasing the density of markers, the allelic derived from Guanghui 998 was finely mapped, and was narrowed down to about 8 kb in the region between markers RM6018 and RM5499 on the chromosomes 7. Comparison analysis of the genomic sequences in the mapped region between Guanghui 998 and Wuyujing 3, a GDP dissociation inhibitor protein gene was identified.4. Analyzing residual heterozygous lines (RHLs) of spnl-7 gene, results showed that, except grain type, stem thickness, leaf width, and panicle size were influenced by spn17 gene. Cytology anatomy showed that, stem cell in small panicle and narrow leaf plants became smaller, and number of outer vascular bundles decreased, resulted in the stem to be thinner; smaller of leaf cell and decreased number of leaf vein resulted in leaf to be narrowed.5. Real time PCR analysis was carried on the typical dominant and recessive plant among the RHLs, and it showed that GDP dissociation inhibitor protein expression quantity in the small panicle and narrow leaf plant were notably increased, which was 2.6 times of that in large panicle and broad leaf plants, and triple of that in the control plant Guanghui 998. it was speculated that rich accumulation of GDP dissociation inhibitor protein gene had blocked the cycle process from inactive status of GDP-binding to active GTP-binding status, and further affected cell skeleton, cell growth and differentiation, and stem, leaf and panicle cell would be smaller.