State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, China.
BMC Plant Biol. 2020 Jan 31;20(1):50. doi: 10.1186/s12870-020-2252-6.
Many studies in Arabidopsis and rice have demonstrated that HD-Zip transcription factors play important roles in plant development and responses to abiotic stresses. Although common wheat (Triticum aestivum L.) is one of the most widely cultivated and consumed food crops in the world, the function of the HD-Zip proteins in wheat is still largely unknown.
To explore the potential biological functions of HD-Zip genes in wheat, we performed a bioinformatics and gene expression analysis of the HD-Zip family. We identified 113 HD-Zip members from wheat and classified them into four subfamilies (I-IV) based on phylogenic analysis against proteins from Arabidopsis, rice, and maize. Most HD-Zip genes are represented by two to three homeoalleles in wheat, which are named as TaHDZX_ZA, TaHDZX_ZB, or TaHDZX_ZD, where X denotes the gene number and Z the wheat chromosome on which it is located. TaHDZs in the same subfamily have similar protein motifs and intron/exon structures. The expression profiles of TaHDZ genes were analysed in different tissues, at different stages of vegetative growth, during seed development, and under drought stress. We found that most TaHDZ genes, especially those in subfamilies I and II, were induced by drought stress, suggesting the potential importance of subfamily I and II TaHDZ members in the responses to abiotic stress. Compared with wild-type (WT) plants, transgenic Arabidopsis plants overexpressing TaHDZ5-6A displayed enhanced drought tolerance, lower water loss rates, higher survival rates, and higher proline content under drought conditions. Additionally, the transcriptome analysis identified a number of differentially expressed genes between 35S::TaHDZ5-6A transgenic and wild-type plants, many of which are involved in stress response.
Our results will facilitate further functional analysis of wheat HD-Zip genes, and also indicate that TaHDZ5-6A may participate in regulating the plant response to drought stress. Our experiments show that TaHDZ5-6A holds great potential for genetic improvement of abiotic stress tolerance in crops.
许多在拟南芥和水稻中的研究表明，HD-Zip 转录因子在植物发育和非生物胁迫响应中发挥重要作用。尽管普通小麦（Triticum aestivum L.）是世界上种植和消费最广泛的粮食作物之一，但 HD-Zip 蛋白在小麦中的功能仍知之甚少。
为了探索小麦中 HD-Zip 基因的潜在生物学功能，我们对 HD-Zip 家族进行了生物信息学和基因表达分析。我们从小麦中鉴定出 113 个 HD-Zip 成员，并根据与拟南芥、水稻和玉米蛋白质的系统发育分析，将它们分为四个亚家族（I-IV）。大多数 HD-Zip 基因在小麦中由两个到三个同源等位基因代表，分别命名为 TaHDZX_ZA、TaHDZX_ZB 或 TaHDZX_ZD，其中 X 表示基因数量，Z 表示其所在的小麦染色体。同一亚家族的 TaHDZ 具有相似的蛋白质基序和内含子/外显子结构。分析了 TaHDZ 基因在不同组织、营养生长不同阶段、种子发育过程和干旱胁迫下的表达谱。我们发现，大多数 TaHDZ 基因，特别是亚家族 I 和 II 的基因，受干旱胁迫诱导，这表明亚家族 I 和 II 的 TaHDZ 成员在非生物胁迫响应中可能具有重要作用。与野生型（WT）植物相比，过表达 TaHDZ5-6A 的转基因拟南芥植物在干旱条件下表现出增强的耐旱性、较低的水分损失率、较高的存活率和较高的脯氨酸含量。此外，转录组分析鉴定了 35S::TaHDZ5-6A 转基因和野生型植物之间的许多差异表达基因，其中许多基因参与胁迫响应。
我们的研究结果将促进对小麦 HD-Zip 基因的进一步功能分析，并表明 TaHDZ5-6A 可能参与调节植物对干旱胁迫的响应。我们的实验表明，TaHDZ5-6A 在提高作物非生物胁迫耐受性的遗传改良方面具有巨大潜力。
