College of Horticulture, Qingdao Agricultural University, Key Laboratory of Horticultural Plant Genetic Improvement and Breeding of Qingdao, 700 Changcheng Road, Qingdao, 266109, China.
BMC Plant Biol. 2021 Jan 6;21(1):11. doi: 10.1186/s12870-020-02764-y.
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.
NAC（NAM、ATAF1/ATAF2 和 CUC2）转录因子属于单子叶和双子叶植物中大型植物特异性转录因子家族。这些转录因子调节与胁迫耐受相关的基因表达，使植物免受各种非生物胁迫的影响，包括干旱、盐度和低温。
本研究在辣椒中鉴定出 CaNAC46 转录因子基因。其开放阅读框揭示包含 921bp，编码由 306 个氨基酸组成的蛋白质，等电点为 6.96。系统进化分析表明，CaNAC46 属于 ATAF 亚家族。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 可能对干椒的非生物胁迫抗性很重要。亚细胞定位分析证实 CaNAC46 定位于细胞核。过表达 CaNAC46 提高了转基因拟南芥植株对干旱和盐胁迫的耐受性。在长时间干旱和高盐胁迫条件下，CaNAC46 过表达系的根长和侧根比野生型系长。此外，CaNAC46 影响活性氧物质（ROS）的积累。此外，CaNAC46 促进 SOD、POD、RD29B、RD20、LDB18、ABI、IAA4 和 P5CS 的表达。干旱和盐胁迫下，TRV2-CaNAC46 系中的丙二醛含量高于野生型植物。此外，TRV2-CaNAC46 植株中应激响应基因如 ABA2、P5CS、DREB、RD22、CAT 和 POD 的表达水平下调。
在盐胁迫和干旱条件下，CaNAC46 是一种正向调节因子，可激活 ROS 清除酶并增强根的形成。本研究结果表明 CaNAC46 是一种与盐度和耐旱性相关的转录调控因子，并表明调控该 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。
