高粱Sbsgr基因家族鉴定、表达与自然等位变异分析

Identification, expression profiling, and natural allelic variation analysis of the Sbsgr gene family in sorghum

摘要:

Stay-green (sgr)基因编码脱镁螯合酶(magnesium dechelatase)，参与叶绿素降解过程，在植物衰老进程和作物产量形成方面发挥重要作用。为系统探究Sbsgr基因的生物学功能及其在胁迫应答中的作用，本研究应用生物信息与分子生物学技术，分析高粱Sbsgr基因的表达模式、启动子区顺式作用元件、互作蛋白与自然等位变异。结果显示，高粱中含有2个sgr同源基因，Sbsgr1为sgr的同源基因，Sbsgr2为sgr-like的同源基因；Sbsgr基因启动子区含干旱胁迫和脱落酸相关的顺式作用元件；2个基因表达模式差异较大，Sbsgr1主要在叶片、穗和种子中表达，Sbsgr2在叶片高水平表达；在干旱、低氮和丝黑穗病菌侵染中，Sbsgr1表达显著上调，而Sbsgr2表达受到抑制；初步鉴定了3个持绿性较好的品种，并在持绿品系‘B35’等材料中，检测到Sbsgr1存在2处单核苷酸多态性(single nucleotide polymorphism, SNP)位点。本研究结果能够为进一步深入研究sgr基因的分子机制提供参考。

Abstract:

Stay-green (sgr) genes encode magnesium dechelatases, which catalyze chlorophyll degradation and play a pivotal role in regulating plant senescence and determining crop yields. This study systematically investigated the biological functions of Sbsgr genes in sorghum and their roles in stress responses, aiming to provide a reference for further research on the molecular mechanisms of sgr genes. Through integrated bioinformatics and molecular biological approaches, we systematically characterized the Sbsgr gene family in sorghum in terms of gene structures, protein physicochemical properties, promoter cis-acting elements, expression profiles, interacting proteins, and natural allelic variations. The results indicated that sorghum carried two sgr homologous genes. Sbsgr1 was an sgr homolog, while Sbsgr2 was an sgr-like homolog. The promoter region of Sbsgr harbored cis-acting elements associated with drought stress and abscisic acid responses. The expression patterns of the two genes differed significantly. Sbsgr1 was primarily expressed in leaves, panicles, and seeds, whereas Sbsgr2 showed high expression levels in leaves. Under drought, low nitrogen, and infection by Sporisorium reilianum, the expression of Sbsgr1 was significantly upregulated, while that of Sbsgr2 was suppressed. Three varieties with strong stay-green traits were preliminarily identified, and two SNP sites in Sbsgr1 were detected in stay-green lines such as ‘B35’. The results of this study can provide a reference for further in-depth research on the molecular mechanism of the sgr gene.