水稻WOX家族基因鉴定及其种子在逆境萌发中的表达分析

Rice WOX family gene identification and expression analysis of seeds germinated under stress

  • 摘要: 【目的】开展水稻WOX基因家族成员的鉴定及在种子逆境萌发中的表达分析,可为探究WOX家族基因的功能、作用机制及水稻遗传改良提供理论参考。【方法】对水稻WOX基因家族成员进行鉴定,利用生物信息学软件对其系统进化关系、理化性质、基因结构、保守结构域、保守基序、顺式作用元件和染色体定位等进行分析,并利用实时荧光定量PCR(qRT-PCR)检测其在种子萌发过程的时空表达特征及非生物胁迫下的表达模式。【结果】从PlantTFDB数据库鉴定获得13个水稻WOX基因家族成员(OsWOX1~OsWOX13),可分为3个分支,其中,远古进化支仅含1个基因,中间进化支和现代进化支分别含有6个基因。13个OsWOXs家族基因不均匀地分布在水稻的1、3、4、5、7、8、11号染色体上,其余5条染色体上则不含该家族基因,其基因结构之间存在较大的差异,暗示WOX基因功能具有差异性和多样性。13个水稻WOX蛋白均定位于细胞核,具有Homodomain superfamily保守结构域和10个保守基序,其中Motif 1和Motif 2位于每个蛋白的保守功能域中。OsWOXs基因启动子区域均含有较多的光响应元件和防御胁迫响应元件,种子特异性反应元件(RY-element)存在于OsWOX1OsWOX9OsWOX11OsWOX12基因中。13个OsWOXs基因在水稻种子萌发及逆境胁迫下的表达模式存在明显差异。OsWOX8基因在萌发种子和幼苗中均呈较高的表达量,OsWOX9OsWOX11基因在种子萌发期表达量较高,而OsWOX2OsWOX6OsWOX8基因在幼苗中的表达量较高。干旱胁迫下,幼苗中OsWOX1OsWOX2OsWOX4OsWOX5基因的相对表达量分别是对照(CK)组的15.0倍、8.0倍、3.9倍和3.6倍,而种子中OsWOX3OsWOX4OsWOX7基因的相对表达量分别比CK组降低87.2%、86.9%和97.8%。【结论】相较于拟南芥和玉米,水稻WOX基因家族成员在系统发育进化上较先进,仅保留OsWOX8一个古老分支,且其启动子区域均含有大量光响应和胁迫响应元件,推测其在功能上偏向于参与光合作用和逆境应答方面。OsWOXs基因在水稻种子萌发、幼苗及各种非生物胁迫下呈现丰富多样的表达模式,其中OsWOX9OsWOX11基因为调控种子萌发的关键基因。

     

    Abstract: 【Objective】To identify rice WOX family gene members and to analyze expression of seeds germinated under stress, so as to provide theoretical reference for exploring function of WOX family genes, mechanism, rice genetic improvement.【Method】WOX family genes were identified. Their phylogenetic evolution relation, physicochemical properties, gene structures, conserved domains, conserved motifs, cis-acting elements, and chromosomal localization were analyzed. Their temporal and spatial expression characteristics and expression patterns under abiotic stress during seed germination were determined through qRT-PCR.【Result】Thirteen rice WOX family gene members(OsWOX1-OsWOX13) were obtained from identification of PlantTFDB data base and they could be divided into 3 branches, in which only 1 belonged to ancient evolutionary branch and 6 intermediate evolutionary branch and 6 modern evolutionary branch. Thirteen genes of OsWOXs family distributed unevenly in chromosome No.1, 3, 4, 5, 7, 8, 11. The rest 5 chromosome did not contain genes from this family. Gene structure differed greatly, indicating WOX gene function had difference and diversity. Thirteen rice WOX proteins located in cell nucleus, with Homodomain superfamily conserved domains and 10 conserved motifs, in which Motif 1 and Motif 2 located in every protein's conserved functional domains. The promoter regions of OsWOXs genes contained more light response elements and defense stress response elements, and seed-specific response elements(RY-element) existed in OsWOX1, OsWOX9, OsWOX11 and OsWOX12 genes. The expression patterns of 13 OsWOXs genes were significantly different under rice seed germination and stress. The expression of OsWOX8 gene was high in germinating seeds and seedlings, the expression of OsWOX9 and OsWOX11 genes was high in germinating seeds and the expression of OsWOX2, OsWOX6 and OsWOX8 genes was high in seedlings. Under drought stress, the relative expression of OsWOX1, OsWOX2, OsWOX4 and OsWOX5 genes in seedlings were 15.0 times, 8.0 times, 3.9 times and 3.6 times higher than those in the control(CK) group, respectively, while the relative expression levels of OsWOX3, OsWOX4 and OsWOX7 genes in seeds were 87.2%, 86.9% and 97.8% lower than those in the CK group, respectively.【Conclusion】OsWOXs gene family members are relatively advanced in phylogeny compared to that in Arabidopsis thaliana and corn, and only OsWOX8 is retained as the only ancient branch. OsWOXs family genes contain lots of light response and stress response elements, which may be more involved in photosynthesis and stress response. OsWOXs gene showed abundant and diverse expression patterns of in rice seed germination, seedling stage and various abiotic stresses and OsWOX9 and OsWOX11 were the key genes regulating seed germination.

     

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