Table_1_Genome-wide identification of wheat ABC1K gene family and functional dissection of TaABC1K3 and TaABC1K6 involved in drought tolerance.PDF

Activity of BC1 complex kinase (ABC1K) serves as an atypical kinase family involved in plant stress resistance. This study identified 44 ABC1K genes in the wheat genome, which contained three clades (I–III). TaABC1K genes generally had similar structural features, but differences were present in motif and exon compositions from different clade members. More type II functional divergence sites were detected between clade I and clade III and no positive selection site were found in TaABC1K family. The three-dimensional structure prediction by Alphafold2 showed that TaABC1K proteins had more α-helixes with a relatively even distribution, and different clade members had differences in the content of secondary structures. The cis-acting element analysis showed that TaABC1K genes contained abundant cis-acting elements related to plant hormones and environmental stress response in the promoter region, and generally displayed a significantly upregulated expression under drought stress. In particular, both TaABC1K3 and TaABC1K6 genes from clade I was highly induced by drought stress, and their overexpression in yeast and Arabidopsis enhanced drought tolerance by suppressing active oxygen burst and reducing photosynthesis impairment. Meanwhile, TaABC1K3 and TaABC1K6 could, respectively, complement the function of Arabidopsis abc1k3 and abc1k6 mutants and reduce photosynthesis damage caused by drought stress.

BC1复合物激酶（ABC1K）家族是一类参与植物抗逆调控的非典型激酶家族。本研究在小麦基因组中鉴定出44个ABC1K基因，可划分为三个进化枝（I~III）。TaABC1K基因整体结构特征较为相似，但不同进化枝成员的基序（motif）与外显子组成存在差异。在进化枝I与进化枝III之间检测到更多的II型功能歧化位点，且TaABC1K家族中未发现正选择位点。通过AlphaFold2进行的三维结构预测显示，TaABC1K蛋白含有较多分布相对均匀的α-螺旋，且不同进化枝成员的二级结构含量存在差异。顺式作用元件（cis-acting element）分析表明，TaABC1K基因的启动子区域含有大量与植物激素及环境胁迫响应相关的顺式作用元件，且在干旱胁迫下普遍呈现显著上调表达。尤为值得注意的是，来自进化枝I的TaABC1K3与TaABC1K6基因均受干旱胁迫高度诱导；二者在酵母与拟南芥（Arabidopsis）中过表达后，可通过抑制活性氧爆发、减轻光合作用损伤，增强宿主的干旱耐受能力。同时，TaABC1K3与TaABC1K6可分别互补拟南芥abc1k3与abc1k6突变体的功能，并缓解干旱胁迫引发的光合作用损伤。