Research On Genes Related With Amylose Content In Yunman Soft Rice "Yunhui290"

Rice is an important food source of human. With the improvement of people’s living standards, cosumer’s demand for rice turns from the quantitative ones to the qualitative ones. Rice quality traits contain processing quality, appearance quality, cooking and eating quality and nutritional quality. Good cooking and eating quality is a project appealing to consumers and the genetical breeders. amylose content(AC) affects cooking and eating quality directly. Cultivar with AC(10%-20%) has better taste. Wx, a major gene controlling AC, can encode Granule-Bound Starch Synthase (GBSS) and affect the AC in endosperm and pollen directly.+1 position G to T mutation of Wx intronl decreases the splicing efficiency of Wx pre-mRNA, which decreases GBSS and AC. Wx is devided into Wxa and Wxb according to 5’splite site of yunhui290 Wx intronl in nonglutinous cultivar. Indica is Wxa generally,+1 position of intronl is G, AC is between 24% and 28%. Japonica is Wxb,+1 position of intronl is T, AC is between 15% and 20%. Indica conventional cultivar Yunhui290 with good eating and cooking quality is breeded from international rice by Food Crops Institute of Yunnan Agriculture Science Academy. Its AC is only 18.72%, which is classified as low AC cultivar. It may have new genes controlling AC which can be used to breed good quality cultivar.Firstly, analyze on yunhui290 Wx:PCR amplification with primer M-Wx design-ed by Gao, template yunhui290’s genome DNA indicates that the 5’splite site of yunhui290 Wx intronl is GG. Sequence analysis of yunhui290 Wx intronl splicing site is GG, which indicates that the low AC of yunhui290 doesn’t resulted from G-T mutation. Sequence analysis also find a CT10 microsatellite fragment, it is related with high AC cultivars, however, AC of yunhui290 with CT10 is only 18.72%. yunhui290 Wx has a mutation in exon9. The 1085th nucleotide starting from ATG, T mutates to C, which results in the 362th amino acide turning from Asp to Arg. Sequence alignment with wx, Wxin, Wxop, Wx-mq, Wxmw, WxHH, In5C, In5De1, In6C, In6T, Ex6A, Ex6C, D4063-1 Wx and Wxhp indicates that the yunhui290 Wx is a new allele, name it WxYH290. It may affect the activity of GBSS or the combination with starch granule, lower the AC of yunhui290.Then, build a F2 population with yunhui290 and minghui63, measure AC of 137 lines, screen 123 polymorphism molecular markers cover entire genome. Analyze data via MAPMAKER3.0 and QTLNetwork, detect a qLAC8 in Chromosome8, between markers A51 and A52, distance 40cM from A51, physical distance is 149079-150300bp, A is +1.1926. Heritability of additive h^2(a) is 6.19%. Compare with positioned AC related QTLs on Chr8, amy8, positioned RM230-RM264, physical distance is 108603-112077bp, LOD value is 3.1, additive effect is-1.85; qAC-8, positioned R727-G1149, physical distance is 138944-148544bp, LOD value is 3.7, additive effect is 1; qAC-8-1, positioned RM7356-RM7556, physical distance is 147655-155542bp, additive effect is-0.71; qAC-8-2, positioned RM23510-RM23579, physical distance is 26723412-2750026bp, additive effect is 0.52; qAC-8-3, positioned near RM1235, physical distance is 156561bp, LOD value is 2.118, additive effect is 0.39. The physical distance of qLAC8 is between that of qAC-8-1,147655-155542bp, qLAC8 and qAC-8-1 may be a same AC-related QTL from different materials, may decrease the AC of yunhui290, this provide new material to genetic quality breeding with certain value.At last, Expression analysis of starch synthesis pathway genes, AGPlar, AGPlso, AGPsma, Wx, SS-Ⅰ, SS-Ⅱ-1, SS-Ⅱ-2, SS-Ⅱ-3, SS-Ⅲ-1, SS-Ⅲ-2, SS-IV-1, SS-Ⅳ-2, SBE1, SBE3, SBE4, ISA, PUL-1 and PUL-2, other genes related with AC, Dul, du3, Ae,flo-1,flo-2 and flo-3. SS-Ⅲ-2 positioned on Chr8,5352105-5362928bp. ISA positioned on Chr8,25893657-25900342bp. Other genes positioned on other chromo-somes. qLAC8 positioned on Chr8,149079-150300bp, indicates that qLAC8 is differ-rent from obove genes.WxYH290 and AC-related qLAC8 may decrease AC of yunhui290. Still need further research to explore specific mechanisms.