小麦果聚糖合成酶基因6-SFT-A单核苷酸多态性分析及其定位

Single Nucleotide Polymorphism and Mapping of 6-SFT-A Gene Responsible for Fructan Biosynthesis in Common Wheat

【目的】小麦果聚糖合成酶基因6-SFT是果聚糖合成过程中的关键酶基因,研究6-SFT-A的多态性,分析其与小麦苗期抗旱性的关系,并进行遗传定位。【方法】以苗期抗旱性不同的30份六倍体小麦和4份小麦A基因组供体种乌拉尔图小麦为材料,通过直接测序分析6-SFT-A的单核苷酸多态性(SNP)及其与抗旱性的关系;开发基因分子标记,利用RIL群体(偃展1号×内乡188)对该基因进行遗传定位。【结果】在30份六倍体小麦材料中检测到14个核苷酸多态性位点,包括13个SNP和1个InDel,平均234 bp检测到一个多态性位点,仅在1 727和1 781 bp 2个位点检测到非同义突变;在4份乌拉尔图小麦中检测到28个SNP和4个InDel,其频率明显高于普通小麦。该基因的内含子1、2、3和外显子3为变异富集区,其它区域变异较小,外显子2变异最小,π值为0。34份材料分为3种单倍型,HaplⅠ主要包括中等抗旱材料和水敏感材料,HaplⅢ中主要包括强抗旱材料和中等抗旱材料。利用RIL群体将该基因定位于染色体4A的标记Xcwm-27与Xwpt688之间,遗传距离分别为5.3和7.9 cM。【结论】单倍型分析表明,小麦果聚糖合成酶基因6-SFT-A单倍型与小麦苗期抗旱性有一定的相关性。

【Objective】 6-SFT is a key gene responsible for the fructan biosynthesis in plants.The objective of the present study was to detect single nucleotide polymorphism（SNP） of 6-SFT-A,determine the relationship between SNP and drought resistance,and mapping it on chromosome of wheat（Triticum aestivum L.）.【Method】 Thirty hexaploid wheat accessions with different drought resistance at seedling stage and four T.urartu,the A genome donor species of hexaploid wheat,were selected to detect the nucleotide polymorphism in 6-SFT-A gene by sequencing,and determine the relationship between SNP and drought resistance.Using the recombinant inbred lines（RIL） derived from a cross Yanzhan 1 × Neixiang 188 mapped 6-SFT-A on chromosome.【Result】 Among the 30 hexaploid accessions,14 polymorphism sites in 6-SFT-A nucleotide sequences were identified,including 13 SNP and one InDel（insertion and deletion） with the polymorphism frequency of 1/234 bp,only two nonsynonymous mutation identified in 1 727 bp and 1 781 bp sites.The introns 1,2,3 and exon 3 were detected as the rich nucleotide variation regions.Exon 2 showed the least variation.Compared to the common wheat,T.urartu species exhibited higher sequence variation.Totally,three haplotypes were identified for the plant materials.HaplotypeⅠconsists of wheat accessions with medium-drought resistance and drought sensitivity.Haplotype Ⅲ includes the wheat accessions with high-and medium-drought resistance.Using a population of 190 recombinant inbred lines derived from a cross of Yanzhan 1 × Neixiang 188,6-SFT-A was mapped on chromosome 4A between SSR markers Xcwm-27 and Xwpt 688,and the genetic distances were 5.3 cM and 7.9 cM from the flanking markers,respectively.【Conclusion】 The present data indicated that SNP in 6-SFT-A gene is associated with wheat seedling drought resistance to some extent.