Key Laboratory of Biology and Genetic Resources of Rubber Tree, Ministry of Agriculture, Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou 571737, China.
Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China.
Plant Sci. 2018 Jun;271:9-19. doi: 10.1016/j.plantsci.2018.03.005. Epub 2018 Mar 7.
NAC transcription factors (TFs) are important regulators of plant adaptation to abiotic stress. In this study, we functionally characterized an NAC TF, ShNAC1, from Solanum habrochaites. ShNAC1 was up-regulated by drought, cold, and salt stresses, and it displayed lower expression at the late stage of stress treatments than its orthologous gene in S. lycopersicum. Overexpression of ShNAC1 in tomato resulted in reduced cold, drought, and salt tolerance. Additionally, ShNAC1 displayed the highest expression in senescent leaf, and overexpressing ShNAC1 accelerated salt- and dark-induced leaf senescence. ShNAC1 was located in the nucleus without transactivation activity. RNA-seq analysis revealed that 81% (190 out of 234) differentially-expressed genes (DEGs) showed down-regulation in the transgenic line L2 compared with wild-type, suggesting that ShNAC1 may function as a transcriptional repressor. Among these down-regulated DEGs, many were involved in stress responses, such as SlHKT1;1, SlMAPKKK59, SlJA2, SlTIL, SlALDH2B1, etc. Noticeably, one ACS gene and three ACO genes involved in ethylene biosynthesis were up-regulated, while seven ERF genes in the ethylene signal transduction pathway were down-regulated in the transgenic lines, respectively. Our results suggested that ShNAC1 negatively regulates tolerance to abiotic stress in tomato probably by modulating the ethylene biosynthesis and signal transduction pathways.
NAC 转录因子（TFs）是植物适应非生物胁迫的重要调节因子。在本研究中，我们从茄科植物番茄（Solanum lycopersicum）中鉴定了一个 NAC TF 基因 ShNAC1，并对其功能进行了研究。ShNAC1 受干旱、寒冷和盐胁迫诱导表达上调，但在胁迫处理后期的表达水平低于其在番茄中的同源基因。番茄中超表达 ShNAC1 导致对寒冷、干旱和盐胁迫的耐受性降低。此外，ShNAC1 在衰老叶片中表达量最高，过表达 ShNAC1 加速了盐和黑暗诱导的叶片衰老。ShNAC1 定位于细胞核内，没有转录激活活性。RNA-seq 分析显示，与野生型相比，转 ShNAC1 基因番茄 L2 中有 81%（190/234）的差异表达基因（DEGs）表达下调，表明 ShNAC1 可能作为转录抑制子发挥作用。在这些下调的 DEGs 中，许多参与胁迫反应，如 SlHKT1;1、SlMAPKKK59、SlJA2、SlTIL、SlALDH2B1 等。值得注意的是，乙烯生物合成途径中的一个 ACS 基因和三个 ACO 基因上调，而乙烯信号转导途径中的七个 ERF 基因下调。我们的研究结果表明，ShNAC1 可能通过调节乙烯生物合成和信号转导途径，负调控番茄对非生物胁迫的耐受性。
