谷子Ⅲ型PRX基因家族全基因组鉴定及干旱胁迫下表达分析

Genome-wide identification of the ClassⅢPRX gene family in foxtail millet(Setaria italica L.)and expression analysis under drought stress

Ⅲ型过氧化物酶(ClassⅢperoxidase,PRX)是植物中特有的过氧化物酶家族,在植物生长发育以及非生物胁迫中发挥重要作用。谷子作为C4植物是禾本科抗逆研究的模式植物,然而目前对于谷子中Ⅲ型过氧化物酶家族基因功能鲜有报道。为探究谷子Ⅲ型过氧化物酶基因家族(SitPRXs)在干旱胁迫和ABA诱导下的表达模式,进行了全基因组表达分析。本研究利用生物信息学方法在谷子全基因组中鉴定出132个Ⅲ型PRX基因家族成员,并根据其在染色体上位置顺序依次命名为SitPRX1~SitPRX132。通过对谷子、拟南芥和水稻的系统进化分析将其分为5个亚家族,基因结构和保守基序分析表明同一亚家族具有较高的保守性。基因复制分析显示,17个SitPRX基因(13%)存在片段复制,78个SitPRX基因(59%)存在串联复制,串联复制事件在SitPRX基因扩增中起重要作用。谷子与拟南芥、水稻和玉米的物种间同源性分析显示谷子中大多数SitPRXs是在双子叶植物和单子叶植物分化后形成的。转录组分析显示,SitPRX基因家族成员在谷子幼苗、根、茎、叶以及圆锥花序中表达存在差异。启动子顺式作用元件分析显示,79个SitPRXs含有与干旱胁迫响应相关的顺式作用元件,进一步qRT-PCR分析显示,SitPRX12、SitPRX41、SitPRX81、SitPRX110和SitPRX126受PEG和ABA诱导表达,表明这些基因可能通过ABA依赖的信号通路来调控和响应干旱胁迫,可作为进一步研究Ⅲ型PRX基因家族抗旱功能的候选基因。研究结果为全面解析SitPRX基因结构与生物学功能、抗旱分子机制以及分子育种提供了新信息,以期为今后培育高效抗逆作物新品种提供思路。

ClassⅢperoxidases(PRX)are a family of plant-specific peroxidases that play an important role in plant growth and development as well as in abiotic stresses.Foxtail millet(Setaria italica L.),as a C4 plant,is a model plant for stress resistance.However,the function of classⅢperoxidases family genes is rarely reported in foxtail millet.A genome-wide expression analysis was conducted to investigate the expression pattern of classⅢperoxidase gene family(SitPRXs)under drought stress and ABA induction.In this study,132 members of the ClassⅢPRX gene family were identified in the whole genome in foxtail millet by bioinformatics and named SitPRX1-SitPRX132 according to their chromosomal position.132 members were classified into Mα,Mβ,Mγ,MIKCC,and MIKC subfamilies by phylogenetic analysis of foxtail millet,Arabidopsis,and rice.Gene structure and conserved motif analysis indicated a high level of conservation in the same subfamily.Gene duplication analysis revealed fragmental duplication in 17 SitPRX genes(13%)and tandem duplication in 78 SitPRX genes(59%),thus tandem duplication events playing an important role in SitPRX gene amplification.Interspecies homology analysis with Arabidopsis,rice and maize revealed that most SitPRXs were formed after dicotyledonous and monocotyledonous plants diverged.Transcriptome analysis implied that members of the SitPRX gene family were differentially expressed in seedlings,roots,stems,and leaves,as well as in panicles in foxtail millet.Analysis of promoter cis-acting elements showed that 79 SitPRXs contained cis-acting elements associated with drought stress response,and further qRT-PCR analysis showed that SitPRX12,SitPRX41,SitPRX81,SitPRX110,and SitPRX126 were induced to be expressed by PEG and ABA,suggesting that these genes may be regulated through an ABA-dependent signalling pathway in response to drought stress and could be used as these genes may be candidates for further studies on the drought resistance function of the classⅢPRX gene family.These results of this study provide new information for the comprehensive analysis of the structure and biological functions of SitPRX genes,the molecular mechanism of drought resistance,and molecular breeding in foxtail millet,with a view of providing ideas for the breeding of new varieties of highly efficient stress-resistant crops in the future.