School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5064, Australia.
Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
Plant Mol Biol. 2018 Apr;96(6):543-561. doi: 10.1007/s11103-018-0713-1. Epub 2018 Mar 21.
The understanding of roles of bZIP factors in biological processes during plant development and under abiotic stresses requires the detailed mechanistic knowledge of behaviour of TFs. Basic leucine zipper (bZIP) transcription factors (TFs) play key roles in the regulation of grain development and plant responses to abiotic stresses. We investigated the role and molecular mechanisms of function of the TabZIP2 gene isolated from drought-stressed wheat plants. Molecular characterisation of TabZIP2 and derived protein included analyses of gene expression and its target promoter, and the influence of interacting partners on the target promoter activation. Two interacting partners of TabZIP2, the 14-3-3 protein, TaWIN1 and the bZIP transcription factor TaABI5L, were identified in a Y2H screen. We established that under elevated ABA levels the activity of TabZIP2 was negatively regulated by the TaWIN1 protein and positively regulated by the SnRK3/CIPK protein kinase WPK4, reported previously to be responsive to nutrient starvation. The physical interaction between the TaWIN1 and the WPK4 was detected. We also compared the influence of homo- and hetero-dimerisation of TabZIP2 and TaABI5L on DNA binding. TabZIP2 gene functional analyses were performed using drought-inducible overexpression of TabZIP2 in transgenic wheat. Transgenic plants grown under moderate drought during flowering, were smaller than control plants, and had fewer spikes and seeds per plant. However, a single seed weight was increased compared to single seed weights of control plants in three of four evaluated transgenic lines. The observed phenotypes of transgenic plants and the regulation of TabZIP2 activity by nutrient starvation-responsive WPK4, suggest that the TabZIP2 could be the part of a signalling pathway, which controls the rearrangement of carbohydrate and nutrient flows in plant organs in response to drought.
理解 bZIP 因子在植物发育过程和非生物胁迫下的生物学过程中的作用，需要详细了解 TF 的行为机制。碱性亮氨酸拉链（bZIP）转录因子（TFs）在调节谷物发育和植物对非生物胁迫的反应中起着关键作用。我们研究了从干旱胁迫小麦植株中分离的 TabZIP2 基因的作用和分子机制。TabZIP2 及其衍生蛋白的分子特征包括基因表达及其靶启动子分析，以及相互作用伙伴对靶启动子激活的影响。在 Y2H 筛选中鉴定了 TabZIP2 的两个相互作用伙伴，即 14-3-3 蛋白 TaWIN1 和 bZIP 转录因子 TaABI5L。我们确定，在 ABA 水平升高的情况下，TabZIP2 的活性受到 TaWIN1 蛋白的负调控，而受到 SnRK3/CIPK 蛋白激酶 WPK4 的正调控，WPK4 先前被报道对营养饥饿有反应。检测到 TaWIN1 和 WPK4 之间的物理相互作用。我们还比较了 TabZIP2 和 TaABI5L 同型和异型二聚化对 DNA 结合的影响。通过在转基因小麦中干旱诱导过表达 TabZIP2 进行了 TabZIP2 基因功能分析。在开花期间适度干旱下生长的转基因植物比对照植物小，每株植物的穗数和种子数较少，但与对照植物相比，在评估的四个转基因系中的三个中，单个种子的重量增加。观察到的转基因植物表型和对营养饥饿反应的 WPK4 调节 TabZIP2 活性表明，TabZIP2 可能是控制植物器官中碳水化合物和养分流重排以响应干旱的信号通路的一部分。
