State Key Laboratory for Agrobiotechnology/Key Laboratory of Crop Heterosis and Utilization (MOE)/Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, PR China.
Plant Physiol. 2021 Aug 3;186(4):1951-1969. doi: 10.1093/plphys/kiab187.
Polyploidy occurs prevalently and plays an important role during plant speciation and evolution. This phenomenon suggests polyploidy could develop novel features that enable them to adapt wider range of environmental conditions compared with diploid progenitors. Bread wheat (Triticum aestivum L., BBAADD) is a typical allohexaploid species and generally exhibits greater salt tolerance than its tetraploid wheat progenitor (BBAA). However, little is known about the underlying molecular basis and the regulatory pathway of this trait. Here, we show that the histone acetyltransferase TaHAG1 acts as a crucial regulator to strengthen salt tolerance of hexaploid wheat. Salinity-induced TaHAG1 expression was associated with tolerance variation in polyploidy wheat. Overexpression, silencing, and CRISPR-mediated knockout of TaHAG1 validated the role of TaHAG1 in salinity tolerance of wheat. TaHAG1 contributed to salt tolerance by modulating reactive oxygen species (ROS) production and signal specificity. Moreover, TaHAG1 directly targeted a subset of genes that are responsible for hydrogen peroxide production, and enrichment of TaHAG1 triggered increased H3 acetylation and transcriptional upregulation of these loci under salt stress. In addition, we found the salinity-induced TaHAG1-mediated ROS production pathway is involved in salt tolerance difference of wheat accessions with varying ploidy. Our findings provide insight into the molecular mechanism of how an epigenetic regulatory factor facilitates adaptability of polyploidy wheat and highlights this epigenetic modulator as a strategy for salt tolerance breeding in bread wheat.
多倍体在植物物种形成和进化过程中普遍存在，并发挥着重要作用。这一现象表明，多倍体可能会产生新的特征，使它们能够比二倍体祖先适应更广泛的环境条件。普通小麦（Triticum aestivum L.，BBAADD）是一种典型的异源六倍体物种，通常比其四倍体小麦祖先（BBAA）表现出更强的耐盐性。然而，人们对这种特性的潜在分子基础和调控途径知之甚少。在这里，我们表明组蛋白乙酰转移酶 TaHAG1 作为一个关键的调节因子，增强了六倍体小麦的耐盐性。盐诱导的 TaHAG1 表达与多倍体小麦的耐盐性变化有关。过表达、沉默和 CRISPR 介导的 TaHAG1 敲除验证了 TaHAG1 在小麦耐盐性中的作用。TaHAG1 通过调节活性氧（ROS）的产生和信号特异性来促进耐盐性。此外，TaHAG1 直接靶向一组负责产生过氧化氢的基因，并且 TaHAG1 的富集触发了这些基因座在盐胁迫下 H3 乙酰化的增加和转录上调。此外，我们发现盐诱导的 TaHAG1 介导的 ROS 产生途径参与了不同倍性小麦品种耐盐性的差异。我们的研究结果提供了关于表观遗传调节因子如何促进多倍体小麦适应性的分子机制的见解，并强调了这种表观遗传调节剂作为面包小麦耐盐性育种的策略。
