The Effects Of Different Constructs Of Wx Gene And Sbe Gene On Starch Quality In Rice (Oryza Sativa L.)

Amylose content is one of the key factors determining the starch quality in rice, and it can be altered by regulation the starch synthesis-related genes expression, especially the Waxy (Wx) gene and starch branching enzyme (Sbe ) gene. In present study, the over-expression of Wx(Wx-cDNA) and the antisense or RNAi of Sbe (Sbe1 or/and Sbe3) were transfered into different rice varieties separately or simultaneously by Agrobacterium-mediated transformation. The results were as followings:1. The effect of Wx gene over-expression construct on starch quality in rice. The homozygous transgenic rice plants, containing the Wx gene over-expression construct derived from three rice cultivars: Wuxiang9915, Guanglingxiangnuo and Suyunuo, were obtained. (1) The level of GBSS protein was enhanced in the transgenic lines derived from Guanglingxiangnuo and Suyunuo, while it was increased or decreased in the transgenic lines derived from Wuxiang9915. (2) The amylose content of transgenic lines which derived from (AC:1.49%) was increased significantly,which reached to 6.48%~20.30%. Compared to Suyunuo, their gel consistency (GC) of starch was hardened; gelatinization temperature (GT) was decreased; some of the RVA characters, such as HPV, PKV, CPV, SBV, CSV and PaT were increased, PeT was decreased. (3) The amylose content of the transgenic lines which derived from Guanglingxiangnuo (AC:1.18%) was also increased significantly, which reached to 4.43%~21.50%. Compared to Guanglingxiangnuo, their GC of starch was hardened; GT was decreased; HPV, PKV, CPV, SBV, CSV, PaT and PeT of RVA were increased. (4) The amylose content of the transgenic lines which derived from Wuxiang9915(AC:15.56%) was in the range 9.24%~31.98%, some of which were increased significantly, some were decreased significantly, some had no significant change; Compared to the wild type, GC was increased and GT was decreased; HPV, CPV, BDV, PKV and PeT of RVA were decreased; PaT was increased; (5) When the amylose content was increased significantly(AC≥10%), the milled rice of the transgenic lines derived from Guanglingxiangnuo and Suyunuo became transparent. 2. The effects of the Wx-cDNA and the antisense or RNAi structure of Sbe gene(s) on rice starch quality. (1)From the offspring of the co-transformants with both the Wx-cDNA and the antisense or RNAi structure of Sbe gene(s) derived from Wuxiang9915 and Guanglingxiangnuo, the homozygous plants containing both genes were obtained. (2) In some transgenic lines selected, the GBSS protein level was enhanced. (3) The amylose contant of the transgenic lines derived from Guanglingxiangnuo was increased to 7.19%~21.40%, and the increasement had reached to very significant level. The GC of the transgenic rice was samller compared with Guanglingxiangnuo, while the GT was decreased. HPV, PeT and PaT of RVA became higher, BDV became smaller. (4)The amylose contant of the transgenic lines derived from Wuxiang 9915 was in the range of 12.13%~19.81%, some of which were increased significantly, some were decreased significantly, some had no significant change; The GC of the transgenic rice was longer compared to the wild type, while the GT was decreased significantly. PKV, HPV and CPV of RVA became samller, PaT became bigger;(5)The brown rice of the selected co-transformed transgenic lines all became crimple.