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作者	单位
田小萍，王光浩，张宏，吉万全	(1.西北农林科技大学农学院/旱区作物逆境生物学国家重点实验室，陕西杨凌 712100；2.农业部作物基因资源与种质创制陕西科学观测实验站，陕西杨凌 712100)

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中文摘要:

GIF1（ grain incomplete filling 1）编码了一种质外体途径中催化蔗糖不可逆水解的细胞壁蔗糖转化酶，主要在组织生长旺盛并且需要供能的库中表达，是影响灌浆的关键基因。根据水稻 OsGIF1基因序列，同源克隆了普通小麦第2部分同源群染色体上的 TaGIF1基因，它包含7个外显子和6个内含子，与水稻 OsGIF1 基因结构相似。小麦 TaGIF1-2A基因含有237 bp的5′ UTR、1 986 bp的ORF、262 bp的3′ UTR，编码661个氨基酸。通过分析15份大小粒小麦品种的gDNA序列，在 TaGIF1-2A基因中共发现21个SNP位点，9个位于编码区，12个位于非编码区。SNP分组发现，15份大小粒小麦品种中 TaGIF1-2A基因共存在8种单倍型。氨基酸序列比对显示，共存在2个氨基酸变异位点，其余SNP位点未引起氨基酸的改变。大小粒品种中无特异SNP变异，表明该基因编码区序列高度保守。就 TaGIF1-2A启动子区而言，大粒材料元件数量和种类均多于小粒材料，而且这些元件均与籽粒发育相关，说明 TaGIF1-2A基因启动子的活跃程度与最终籽粒灌浆饱满度的形成可能存在密切联系。qRT-PCR分析表明， TaGIF1-2A在籽粒和颖壳中都有表达，在不同小麦材料中表达模式相同，说明与籽粒大小无关；而在2~6 DAA的籽粒中，表达量剧烈上调，而后急剧下调，由此推测 TaGIF1-2A可能影响籽粒灌浆，在灌浆前期与籽粒发育密切相关。亚细胞定位结果表明， TaGIF1-2A 主要作用在细胞壁上。

英文摘要:

GIF1（ grain incomplete filling 1） encodes a kind of cell wall sucrose invertase which catalyzes sucrose hydrolysis irreversibly in apoplast pathway. It is mainly expressed in the reservoir where tissues grow vigorously and need energy supply,and it is a key gene affecting grain filling. According to the sequence of OsGIF1-2A gene in rice,the TaGIF1 gene on the chromosomes of homeologous group two in common wheat was cloned homologously. It contains seven exons and six introns,which is similar to the structure of OsGIF1 gene in rice. TaGIF1-2A gene contains 5′UTR(237 bp),ORF (1 986 bp) and 3′UTR(262 bp),encoding 661 amino acids. By analyzing the gDNA sequences in ten large-grain and five small-grain wheat varieties,21 SNP loci were successfully found in TaGIF1-2A. Among them,nine SNP loci are located in the coding region while the other 12 SNPs are located in the non-coding region. SNP analysis showed that there are eight haplotypes of TaGIF1-2A gene within the 15 wheat varieties. Amino acid sequence alignment showed that there were two amino acid variants,and the remaining SNP loci did not cause amino acid changes. There was no specific SNP variation in the large- or small-grain varieties,indicating that the coding sequence of the gene was relatively conserved. As far as the promoter region of TaGIF1-2A is concerned,both the number and types of elements of the large-grain materials were more than those of the small-grain materials,indicating that the promoter region of TaGIF1-2A gene may be closely related to grain filling. qRT-PCR results showed that TaGIF1-2A was expressed in both grain and glume,and the same expression pattern was found in large-grain and small-grain varieties,suggesting that it was not related to grain size. However,the expression was significantly up-regulated in grains at 2-6 DAA and then the expression was sharply decreased. It is speculated that TaGIF1 may affect grain filling,and it is closely related to grain development at the early stage of grain filling. The subcellular localization results indicated that TaGIF1-2A mainly acted on the cell wall.

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