ERF-Ⅶ转录因子RAP2.12调控淹水诱导拟南芥幼苗花青素合成

ERF-Ⅶ transcription factor RAP2.12 regulates submergence-induced anthocyanin biosynthesis in Arabidopsis thaliana seedlings

关键词:  拟南芥, 淹水, 花青素, RAP2.12, MYB75

Key words:  Arabidopsis thaliana, submergence, anthocyanin, RAP2.12, MYB75

摘要:

淹水胁迫会导致植物缺氧从而影响植物的生长发育。已有研究表明淹水会诱导植物积累花青素,但其分子机制尚不明确。为解析ERF-Ⅶ家族转录因子在淹水诱导花青素合成中的作用及其调控机制,该研究以拟南芥(Arabidopsis thaliana)为研究对象,分析相关材料在淹水处理条件下花青素积累情况,并采用酵母双杂交、双分子荧光互补(BiFC)等实验验证RAP2.12与MYB75蛋白的相互作用关系。此外,为明确其调控途径,从遗传学和分子层面对RAP2.12调控花青素合成的功能进行了系统分析。结果表明:(1)淹水促进花青素积累的过程依赖于MBW复合体。(2)ERF-Ⅶ转录因子家族成员RAP2.12能够与MYB75蛋白相互作用,并且二者协同激活花青素合成基因(DFR、LDOX)的转录。(3)rap2.2 2.3 2.12突变体对淹水诱导的花青素积累不敏感,而(MA)RAP2.12-HA高表达植株对淹水诱导的花青素积累超敏感,表明其调控花青素合成过程。(4)遗传学分析结果进一步表明,在淹水胁迫条件下,RAP2.12对花青素积累的调控作用主要依赖MYB转录因子家族。综上所述,RAP2.12通过与MYB75相互作用,调控拟南芥幼苗在淹水胁迫下的花青素合成与积累。该研究拓展了ERF-Ⅶ转录因子在植物低氧适应中的功能,为解析植物应对淹水胁迫的分子机制及农作物育种提供了理论依据。

Abstract:

Submergence stress, a major environmental constraint in agriculture, causes oxygen deficiency in plant tissues, thereby impairing plant growth, development, and survival. One notable adaptive response of plants to submergence is the accumulation of anthocyanins — flavonoid pigments with strong antioxidant properties that help mitigate reactive oxygen species(ROS)-induced damage. These compounds also play important roles in stress signaling and metabolic reprogramming. Although enhanced anthocyanin accumulation under submergence has been observed in multiple plant species, the underlying regulatory mechanisms, particularly at the transcriptional level, remain poorly understood. To clarify the molecular mechanism of submergence-induced anthocyanin biosynthesis, this study investigated the role of ERF-Ⅶ(ethylene response factor group Ⅶ)transcription factors in Arabidopsis thaliana. Anthocyanin levels were measured in various genotypes exposed to submergence treatment conditions. In addition, protein-protein interaction assays, including yeast two-hybrid(Y2H)and bimolecular fluorescence complementation(BiFC), were conducted to examine physical interactions between ERF-Ⅶ members and known regulators of anthocyanin biosynthesis. In addition, to elucidate its regulatory pathway, a systematic analysis of the role of RAP2.12 in regulating anthocyanin biosynthesis was conducted at both genetic and molecular levels. The results were as follows:(1)Anthocyanin accumulation under submergence depended on MBW complex, composed of MYB, bHLH, and WD40 proteins, which served as a central regulatory hub in flavonoid biosynthesis.(2)RAP2.12 physically interacted with MYB75, MYB90, and MYB113, and these interactions synergistically activated the expression of anthocyanin biosynthetic genes such as DFR and LDOX, indicating a transcriptional co-activation mechanism.(3)The rap2.2 2.3 2.12 triple mutant exhibited reduced sensitivity to submergence-induced anthocyanin accumulation, while (MA)RAP2.12-HA overexpression lines showed hypersensitivity, indicating that RAP2.12 promotes anthocyanin biosynthesis under submergence and acts as a positive regulator in this stress-adaptive pathway.(4)Genetic analysis revealed that the regulatory function of RAP2.12 was primarily dependent on MYB transcription factors, as RAP2.12 alone could not activate downstream gene expression in the absence of functional MYB proteins. In conclusion, RAP2.12 regulates anthocyanin biosynthesis and accumulation in A. thaliana seedlings under submergence stress by physically interacting with MYB75. It enhances the transcriptional activity of the MBW complex, thereby promoting the expression of key structural genes in the anthocyanin biosynthetic pathway. These findings expand our understanding of the roles of ERF-Ⅶ transcription factors in plant adaptation to hypoxic environments. Furthermore, this work provides novel insights into how environmental signals are integrated through transcriptional regulators to coordinate secondary metabolism and stress responses. It also provides a theoretical basis for understanding the molecular mechanism of plant response submergence stress and crop breeding.