Investigation Of The Effects Of Starch Synthesis Related Genes On Rice (Oryza Sativa L.) Qualities Using Near Isogenic Lines

The yield level of rice has been dramatically improved mainly as the result of genetic improvement, increasing harvest index by reducing plant height with the semidwarf gene sd-1, and utilization of heterosis by producing hybrids. High yield and good quality are main objectives in rice breeding program, now more and more varieties with high resistance and high yield potnetied are releasd developed by breeders, but high quality varieties are few. With the improvement of people’s living level, the requirement of rice with good quality has become higher and higher, especially in cooking and eating quality. Hence, rice cooking and eating quality, genetic characteristics and variety improvement has been widespread concerned by breeders. The main components of rice grain is starch, whose composition and structure in a certain extent determine the rice quality, Thus, it is necessary to understand the mechanisms underlying the rice starch biosynthesis, and then provide the basic knowledge.In this study, Guichao2(indica) and Suyunuo (japonica) were selected as materials, which differ dramatically in grain quality. The near-isogenie lines (NILs) for12starch synthesis related genes (SSRG) are constructed with Guichao2as the recurrent parents and Suyunuo as the donor parent through molecular marker-assisted selection. And the grain quality were measured, including RVA profile, GC, DSCand GT. The genetic effects of12starch synthesis related genes were. The main results are summarized as following:1. Through molecular marker detection, the genetic backgrounds of NILs are basically consistent with that of Guichao2, except for their corresponding target genes.Moreover, the agronomic traits analysis showed that there are no significant differences between NILs and the recurrent parent, suggesting that the developed NILs are qualified for studing the genetic effects of SSRGs. 2. Amylose content analysis showed that the AC of NILs changed when compared that of Guichao2, especially for NIL-SSII-3and NIL-SSⅣ-2, indicating that the amylopectin synthesis related gene have differentiated between in indica and japonica group in terms of their functions,3. The gel consistency analysis showed that the gel length altered NIL-SSIV-1, NIL-SSⅣ-2,NIL-Sbel, NIL-SSⅡ-3, NIL-Pull and NIL-Isa, suggesting these genes are also involved in the control of gel consistency, varying across differences environments.4. The SSRGs have different effects on the RVA characteristics, of which, SSII-2, SSⅢ-1and Pull gene have significant on CPV, SSII-2, SSIII-1and Sbe3gene have significant on HKV, and SSⅡ-1, SSIII-1, Isa have significant on PKV, and Isa is found to mainly control BDV,SSⅠ,SSⅡ-2,SSⅣ-1,SSⅣ-2and Sbe3are for SBV, CSV is found to be controlled by SSII-2,SSⅣ-1, SSⅣ-2, Sbel, Sbe3, SSI. Additionnaly, Isa, Sbe3are found to moderate the PeT characteristic, Taken together, we foundSSⅡ-2,SSⅡ-3,SSⅢ-1,SSⅣ-1, Sbe3, Isa and Pull play important role in determining the starch physico-chemical properties, and differentiate functionally at least between indica variety Guichao2and japonica variety Suyunuo.5. The results also showed that SSⅡ-3and SSIII-2have significant effect on gelatinization propeity, are the characteristic of DSC alter in some extent in the comerponding NILs when compared to the recurrent parent. In addition, SSIII-1, Isa and Pull are also found to be involved in the control of DSC with minor effects.