Muthusamy Senthilkumar K, Dalal Monika, Chinnusamy Viswanathan, Bansal Kailash C
ICAR-National Research Centre on Plant Biotechnology, New Delhi, 110012, India; Division of Crop Improvement, ICAR-Indian Institute of Wheat and Barley Research, Karnal, 132001, India.
ICAR-National Research Centre on Plant Biotechnology, New Delhi, 110012, India.
J Plant Physiol. 2017 Apr;211:100-113. doi: 10.1016/j.jplph.2017.01.004. Epub 2017 Jan 22.
Small Heat Shock Proteins (sHSPs)/HSP20 are molecular chaperones that protect plants by preventing protein aggregation during abiotic stress conditions, especially heat stress. Due to global climate change, high temperature is emerging as a major threat to wheat productivity. Thus, the identification of HSP20 and analysis of HSP transcriptional regulation under different abiotic stresses in wheat would help in understanding the role of these proteins in abiotic stress tolerance. We used sequences of known rice and Arabidopsis HSP20 HMM profiles as queries against publicly available wheat genome and wheat full length cDNA databases (TriFLDB) to identify the respective orthologues from wheat. 163 TaHSP20 (including 109 sHSP and 54 ACD) genes were identified and classified according to the sub-cellular localization and phylogenetic relationship with sequenced grass genomes (Oryza sativa, Sorghum bicolor, Zea mays, Brachypodium distachyon and Setaria italica). Spatio-temporal, biotic and abiotic stress-specific expression patterns in normalized RNA seq and wheat array datasets revealed constitutive as well as inductive responses of HSP20 in different tissues and developmental stages of wheat. Promoter analysis of TaHSP20 genes showed the presence of tissue-specific, biotic, abiotic, light-responsive, circadian and cell cycle-responsive cis-regulatory elements. 14 TaHSP20 family genes were under the regulation of 8 TamiRNA genes. The expression levels of twelve HSP20 genes were studied under abiotic stress conditions in the drought- and heat-tolerant wheat genotype C306. Of the 13 TaHSP20 genes, TaHSP16.9H-CI showed high constitutive expression with upregulation only under salt stress. Both heat and salt stresses upregulated the expression of TaHSP17.4-CI, TaHSP17.7A-CI, TaHSP19.1-CIII, TaACD20.0B-CII and TaACD20.6C-CIV, while TaHSP23.7-MTI was specifically induced only under heat stress. Our results showed that the identified TaHSP20 genes play an important role under different abiotic stress conditions. Thus, the results illustrate the complexity of the TaHSP20 gene family and its stress regulation in wheat, and suggest that sHSPs as attractive breeding targets for improvement of the heat tolerance of wheat.
小分子热激蛋白（sHSPs）/HSP20是一类分子伴侣，在非生物胁迫条件下，尤其是热胁迫期间，通过防止蛋白质聚集来保护植物。由于全球气候变化，高温正成为小麦生产力的主要威胁。因此，鉴定小麦中的HSP20并分析其在不同非生物胁迫下的转录调控，将有助于了解这些蛋白质在非生物胁迫耐受性中的作用。我们使用已知的水稻和拟南芥HSP20隐马尔可夫模型（HMM）序列作为查询序列，对公开可用的小麦基因组和小麦全长cDNA数据库（TriFLDB）进行检索，以从小麦中鉴定各自的直系同源物。共鉴定出163个TaHSP20基因（包括109个sHSP和54个ACD），并根据亚细胞定位以及与已测序禾本科基因组（水稻、高粱、玉米、短柄草和谷子）的系统发育关系进行分类。标准化RNA测序和小麦芯片数据集中的时空、生物和非生物胁迫特异性表达模式揭示了HSP20在小麦不同组织和发育阶段的组成型以及诱导型反应。TaHSP20基因的启动子分析表明存在组织特异性、生物、非生物、光响应、昼夜节律和细胞周期响应的顺式调控元件。14个TaHSP20家族基因受8个Ta-miRNA基因调控。在耐旱和耐热小麦基因型C306中，研究了12个HSP20基因在非生物胁迫条件下的表达水平。在13个TaHSP20基因中，TaHSP16.9H-CI表现出高组成型表达，仅在盐胁迫下上调。热胁迫和盐胁迫均上调了TaHSP17.4-CI、TaHSP17.7A-CI、TaHSP19.1-CIII、TaACD20.0B-CII和TaACD20.6C-CIV的表达，而TaHSP23.7-MTI仅在热胁迫下被特异性诱导。我们的结果表明，鉴定出的TaHSP20基因在不同非生物胁迫条件下起重要作用。因此，这些结果说明了TaHSP20基因家族及其在小麦中的胁迫调控的复杂性，并表明sHSPs是提高小麦耐热性的有吸引力的育种目标。
