谷子β-胡萝卜素异构酶家族基因的表达与变异分析

Analyses on the Transcription and Structure Variation of β-carotene Isomerase Gene Family in Foxtail Millet

株型是影响谷类作物产量的重要性状,株型改良对提高作物产量具有重要意义。独脚金内酯(strigolactones,SLs)作为一种最新被鉴定的植物激素,其通过抑制腋芽的伸长调控分枝/分蘖的形成。β-胡萝卜素异构酶(D27s)是SLs合成途径的关键酶,通过对谷子(Setaria italica)β-胡萝卜素异构酶典型结构域Pfam:DUF4033进行分析,鉴定到3个谷子D27s基因家族成员(Seita.8G168400、Seita.6G088800和Seita.3G050900)。蛋白质特性分析显示,谷子D27s蛋白由271–277个氨基酸残基组成,分子量为30.1–30.4 k Da,等电点为5.85–9.31,不稳定系数介于38.48–74.47之间,且均定位于叶绿体;系统进化分析发现,谷子D27s家族成员位于3个不同进化分支;顺式作用元件预测显示,SiD27-1(Seita.8G168400)可能参与调控生物节律、生长素介导的生长发育以及干旱和低温等胁迫应答过程。基因表达分析显示,SiD27-1在谷子多分蘖材料中表达下调,在低磷胁迫处理下,D27s基因均能产生不同程度的响应,并且Si D27-1的响应较其它成员更快速。单倍型分析结果表明,SiD27-1的H001单倍型为优异单倍型,对谷子的株高、抽穗期和产量改良具有重要应用价值。综上,推测SiD27-1极可能在SLs合成中发挥关键作用并对谷子株型产生影响。研究结果为深入揭示D27s对谷子分蘖形成的调控机制奠定了基础,也为谷子株型分子设计育种提供了优异的等位变异位点。

Plant architecture is of great importance for yield improvement of cereal crops,and improvement of plant architecture is of great significance for improving crop yield potential.As a newly identified plant hormone,strigolactones is one of plant hormones regulating branching and tillering by inhibiting the elongation of axillary buds.β-carotene isomerase is the key enzyme for strigolactone synthesis.By the typical domain Pfam:DUF4033,all members in theβ-carotene isomerase gene family in foxtail millet(Setaria italica)were identified(Seita.8G168400,Seita.6G088800,Seita.3G-050900),encoding 271 to 277 amino acid residues with molecular weight ranging from 30.1 kDa to 30.4 kDa,isoelectric point ranging from 5.85 to 9.31,and instability coefficient ranging from 38.48 to 74.47.All members were subcellularly localized in chloroplast,and were grouped into three different evolutionary branches.Cis-element analysis revealed that Si D27-1(Seita.8G168400)was involved in regulating circadian rhythm,auxin-mediated development,and response to drought and low temperature.Transcription of Si D27-1 was down-regulated in foxtail millet accessions with more tillers,and in low phosphorus treatment could respond to faster than all other members.Haplotype variation analysis revealed that H001 of SiD27-1 may contribute more to plant height,heading date and grain yield than other haplotypes.We inferred that Si D27-1 was involved in strigolactone synthesis and plant architecture in foxtail millet.It laid the foundation for in-depth analysis of regulatory mechanism of D27s on the formation of foxtail millet tillering,and provided allelic variation sites for molecular breeding of foxtail millet.