Bhattacharjee Payel, Das Rohit, Mandal Arunava, Kundu Pallob
Division of Plant Biology, Bose Institute, P1/12 CIT Scheme VII (M), Kolkata, 700054, India.
Plant Mol Biol. 2017 Mar;93(4-5):511-532. doi: 10.1007/s11103-016-0579-z. Epub 2016 Dec 30.
Genome-wide analysis was carried out to identify and analyze differential expression pattern of tomato membrane bound NAC transcription factors (SlNACMTFs) during stresses. Two biotic-stress-related SlNACMTFs have been characterized to elucidate their regulatory function. NAC transcription factors are known regulators of stress-related gene expression. As Stresses are perceived and transmitted by membrane-bound proteins, functional characterization of membrane-associated NAC transcription factors in tomato can reveal valuable insight about membrane-mediated stress-signalling. Tomato genome encodes 13 NAC genes which have predicted transmembrane domain(s) (SlNACMTFs). mRNA of 12 SlNACMTFs were readily detected in multiple tissues, and also in polysome isolated from leaf, confirming active transcription and translation from these genes occur under normal physiological condition. Additionally, most of the SlNACMTFs were differentially regulated during stresses and stress-related transcription factor binding sites are prevalent in their promoters. SlNACMTF3 and 8 were majorly regulated in biotic and abiotic stresses. Like other MTFs, SlNACMTF3 was translocated to the plasma membrane, whereas the C-terminus truncated (ΔC) form localized in the cytoplasm and the nucleus. Accordingly, the ΔC forms significantly influenced the activity of promoters harbouring NAC binding sites (NACbs). Furthermore, the NAC domain of these transcription factors could directly interact with an NACbs, and the proteins failed to regulate a promoter lacking a crucial NACbs. Interestingly, the type of influence to an NACbs containing promoter was dependent on the context of the NACbs, as the same SlNACMTF showed an alternative mode of regulation on different promoters, as well as the same promoter activity was oppositely regulated by two different SlNACMTF. Finally, both SlNACMTFs demonstrated the differential regulatory effect on the expression of several stress-related genes by interacting with the putative NACbs in their promoter region, suggesting their direct role in plant stress response.
开展全基因组分析以鉴定和分析番茄膜结合NAC转录因子（SlNACMTFs）在胁迫期间的差异表达模式。已对两个与生物胁迫相关的SlNACMTFs进行了表征，以阐明其调控功能。NAC转录因子是已知的胁迫相关基因表达的调节因子。由于胁迫是由膜结合蛋白感知和传递的，番茄中膜相关NAC转录因子的功能表征可以揭示有关膜介导的胁迫信号传导的有价值的见解。番茄基因组编码13个具有预测跨膜结构域的NAC基因（SlNACMTFs）。在多个组织以及从叶片分离的多核糖体中很容易检测到12个SlNACMTFs的mRNA，证实这些基因在正常生理条件下发生了活跃的转录和翻译。此外，大多数SlNACMTFs在胁迫期间受到差异调节，并且胁迫相关转录因子结合位点在其启动子中普遍存在。SlNACMTF3和8在生物和非生物胁迫中主要受到调控。与其他MTFs一样，SlNACMTF3易位到质膜，而C端截短（ΔC）形式定位于细胞质和细胞核。因此，ΔC形式显著影响含有NAC结合位点（NACbs）的启动子的活性。此外，这些转录因子的NAC结构域可以直接与NACbs相互作用，并且这些蛋白质无法调节缺乏关键NACbs的启动子。有趣的是，对含有NACbs的启动子的影响类型取决于NACbs的背景，因为相同的SlNACMTF在不同的启动子上表现出不同的调节模式，并且相同的启动子活性受到两种不同的SlNACMTF的相反调节。最后，两个SlNACMTFs通过与其启动子区域中的推定NACbs相互作用，对几个胁迫相关基因的表达表现出差异调节作用，表明它们在植物胁迫反应中具有直接作用。
