The NAC (NAM, ATAF1/ATAF2, and CUC2) transcription factors belong to a large family of plant-specific transcription factors in monocot and dicot species. These transcription factors regulate the expression of stress tolerance-related genes that protect plants from various abiotic stresses, including drought, salinity, and low temperatures. In this study, we identified the CaNAC46 transcription factor gene in Capsicum annuum. Its open reading frame was revealed to comprise 921 bp, encoding a protein consisting of 306 amino acids, with an isoelectric point of 6.96. A phylogenetic analysis indicated that CaNAC46 belongs to the ATAF subfamily. The expression of CaNAC46 was induced by heat, cold, high salt, drought, abscisic acid, salicylic acid, and methyl jasmonate treatments. Thus, CaNAC46 may be important for the resistance of dry pepper to abiotic stresses. A subcellular localization analysis confirmed that CaNAC46 is localized in the nucleus. The overexpression of CaNAC46 improved the tolerance of transgenic Arabidopsis thaliana plants to drought and salt stresses. The CaNAC46-overexpressing lines had longer roots and more lateral roots than wild-type lines under prolonged drought and high salt stress conditions. Additionally, CaNAC46 affected the accumulation of reactive oxygen species (ROS). Moreover, CaNAC46 promoted the expression of SOD, POD, RD29B, RD20, LDB18, ABI, IAA4, and P5CS. The malondialdehyde contents were higher in TRV2-CaNAC46 lines than in wild-type plants in response to drought and salt stresses. Furthermore, the expression levels of stress-responsive genes, such as ABA2, P5CS, DREB, RD22, CAT, and POD, were down-regulated in TRV2-CaNAC46 plants. Under saline and drought conditions, CaNAC46 is a positive regulator that activates ROS-scavenging enzymes and enhances root formation. The results of our study indicate CaNAC46 is a transcriptional regulator responsible for salinity and drought tolerance and suggest the abiotic stress-related gene regulatory mechanisms controlling this NAC transcription factor are conserved between A. thaliana and pepper.

中文翻译：

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NAC型转录因子CaNAC46调控转基因拟南芥的耐盐耐旱性

NAC（NAM、ATAF1/ATAF2 和 CUC2）转录因子属于单子叶植物和双子叶植物中的一大类植物特异性转录因子。这些转录因子调节胁迫耐受相关基因的表达，这些基因保护植物免受各种非生物胁迫，包括干旱、盐分和低温。在这项研究中，我们鉴定了辣椒中的 CaNAC46 转录因子基因。其开放阅读框为921 bp，编码由306个氨基酸组成的蛋白质，等电点为6.96。系统发育分析表明CaNAC46 属于ATAF 亚科。CaNAC46的表达受热、冷、高盐、干旱、脱落酸、水杨酸和茉莉酸甲酯处理诱导。因此，CaNAC46 可能对干辣椒对非生物胁迫的抗性很重要。亚细胞定位分析证实 CaNAC46 位于细胞核中。CaNAC46 的过表达提高了转基因拟南芥植物对干旱和盐胁迫的耐受性。在长期干旱和高盐胁迫条件下，CaNAC46 过表达株系比野生型株系具有更长的根和更多的侧根。此外，CaNAC46 影响活性氧 (ROS) 的积累。此外，CaNAC46 促进 SOD、POD、RD29B、RD20、LDB18、ABI、IAA4 和 P5CS 的表达。响应干旱和盐胁迫，TRV2-CaNAC46 系中的丙二醛含量高于野生型植物。此外，应激反应基因的表达水平，如 ABA2、P5CS、DREB、RD22、CAT 和 POD，在 TRV2-CaNAC46 植物中下调。在盐碱地和干旱条件下，CaNAC46 是一种正调节剂，可激活 ROS 清除酶并促进根的形成。我们的研究结果表明，CaNAC46 是一种负责盐度和耐旱性的转录调节因子，并表明控制该 NAC 转录因子的非生物胁迫相关基因调控机制在拟南芥和辣椒之间是保守的。