School of Life Sciences, Shandong University, Qingdao, Shandong, China.
School of Computer Science and Technology, Tianjin University, Tianjin, China.
Plant J. 2019 Jul;99(1):81-97. doi: 10.1111/tpj.14310. Epub 2019 Apr 14.
T. HALOPHILA HOMEOBOX PROTEIN 1(TsHD1) cloned from the halophyte Thellungiella halophila is a homeodomain (HD) transcription factor gene and functions as a collaborator of TsNAC1. TsHD1 can form heterodimers with TsNAC1 via the interaction between its zinc finger (ZF) domain and the A subdomain of TsNAC1. The overexpression of TsHD1 improved the heat stress resistance of T. halophila and retarded its vegetative growth slightly. The co-overexpression of TsHD1 and TsNAC1 highly improved heat and drought stress resistance by increasing the accumulation of heat shock proteins and enhancing the expression levels of drought stress response genes, such as MYB DOMAIN PROTEIN 77 and MYB DOMAIN PROTEIN 96 (MYB77and MYB96) and SALT TOLERANCE ZINC FINGER 10 and SALT TOLERANCE ZINC FINGER 18 (ZAT10 and ZAT18), but seriously retarded the vegetative growth of T. halophila by restraining cell expansion. The heterodimer of TsHD1 and TsNAC1 has higher transcriptional activation activity and higher stability compared with the homodimer of TsHD1 or TsNAC1. The binding sites of the TsHD1 and TsNAC1 heterodimers were found to exist in the promoters of most upregulated genes in Cauliflower mosaic virus 35S promoter (P35S)::TsHD1 and P35S::TsNAC1 transgene lines compared with the wild type using RNA-seq and genomic data analyses. Moreover, the binding sites in the promoter region of the most downregulated genes were located in the vicinity of the TATA-box. This study reveals that TsNAC1 and TsHD1 play roles in plant growth and abiotic stress resistance synergistically, and the effects depend on the heterodimer binding to the specific target sites in the promoter region.
从盐生植物盐芥（Thellungiella halophila）克隆的 T. HALOPHILA HOMEOBOX PROTEIN 1（TsHD1）是一个同源结构域（HD）转录因子基因，作为 TsNAC1 的协同因子发挥作用。TsHD1 可以通过其锌指（ZF）结构域与 TsNAC1 的 A 亚结构域之间的相互作用与 TsNAC1 形成异二聚体。TsHD1 的过表达提高了盐芥对热胁迫的抗性，并轻微延缓其营养生长。TsHD1 和 TsNAC1 的共过表达通过增加热休克蛋白的积累和增强干旱胁迫应答基因（如 MYB DOMAIN PROTEIN 77 和 MYB DOMAIN PROTEIN 96（MYB77 和 MYB96）和 SALT TOLERANCE ZINC FINGER 10 和 SALT TOLERANCE ZINC FINGER 18（ZAT10 和 ZAT18）的表达水平，高度提高了热和干旱胁迫抗性，但通过抑制细胞扩张严重延缓了盐芥的营养生长。与 TsHD1 或 TsNAC1 的同源二聚体相比，TsHD1 和 TsNAC1 的异二聚体具有更高的转录激活活性和更高的稳定性。通过 RNA-seq 和基因组数据分析，发现 TsHD1 和 TsNAC1 异二聚体的结合位点存在于 Cauliflower mosaic virus 35S 启动子（P35S）::TsHD1 和 P35S::TsNAC1 转基因系中大多数上调基因的启动子中，而在野生型中则不存在。此外，大多数下调基因启动子区域的结合位点位于 TATA 盒附近。这项研究表明，TsNAC1 和 TsHD1 协同作用于植物生长和非生物胁迫抗性，其效应取决于异二聚体结合到启动子区域的特定靶位。
