Ahmad Muhammad Zulfiqar, Shah Zamarud, Ullah Arif, Ahmed Shakeel, Ahmad Bushra, Khan Afrasyab
Department of Plant Breeding and Genetics, Faculty of Agriculture, University of Agriculture, D.I. Khan, Pakistan.
Department of Biotechnology, University of Science and Technology, Bannu, Pakistan.
Mol Biol Rep. 2022 Dec;49(12):11229-11241. doi: 10.1007/s11033-022-07734-1. Epub 2022 Jul 4.
Heat shock protein 70 (HSP70) proteins play a crucial role in mitigating the detrimental effects of abiotic stresses in plants. In the present study, 21 full length non-redundant SlHSP70 genes were detected and characterized in tomato (Solanum lycopersicum L.). The SlHSP70 genes were classified into four groups based on phylogenetic analysis. Similarities were observed in gene features and motif structures of SlHSP70s belonging to the same group. SlHSP70 genes were unevenly and unequally mapped on 11 chromosomes. Segmental and tandem duplication are the main events that have contributed to the expansion of the SlHSP70 genes. A large number of groups and sub-groups were generated during comparative analysis of HSP70 genes in multiple plant species including tomato. These findings indicated a common ancestor which created diverse sub-groups prior to a mono-dicot split. The selection pressure on specific codons was identified through a maximum-likelihood approach and we found some important coding sites in the coding region of all groups. Diversifying positive selection was indirectly associated with evolutionary changes in SlHSP70 proteins and suggests that gene evolution modulated the tomato domestication event. In addition, expression analysis using RNA-seq revealed that 21 SlHSP70 genes were differentially expressed in response to drought and heat stress. SlHSP70-5 was down-regulated by heat treatment and up-regulated by drought stress. Furthermore, the expression of some of the duplicate genes was partially redundant, while others showed functional diversity. Our results indicate the diverse role of HSP70 gene family in S. lycopersicum under drought and heat stress conditions and open the gate for further investigation of HSP70 gene family functions, especially under drought and heat stress.
热休克蛋白70（HSP70）在减轻植物非生物胁迫的有害影响方面发挥着关键作用。在本研究中，在番茄（Solanum lycopersicum L.）中检测并鉴定了21个全长非冗余SlHSP70基因。基于系统发育分析，SlHSP70基因被分为四组。属于同一组的SlHSP70s在基因特征和基序结构上具有相似性。SlHSP70基因不均匀且不等地定位在11条染色体上。片段重复和串联重复是导致SlHSP70基因扩增的主要事件。在包括番茄在内的多种植物物种的HSP70基因比较分析过程中产生了大量的组和亚组。这些发现表明存在一个共同祖先，它在单子叶植物和双子叶植物分化之前就产生了不同的亚组。通过最大似然法确定了对特定密码子的选择压力，我们在所有组的编码区发现了一些重要的编码位点。多样化的正选择与SlHSP70蛋白的进化变化间接相关，表明基因进化调节了番茄驯化事件。此外，使用RNA-seq的表达分析表明，21个SlHSP70基因在干旱和热胁迫下差异表达。SlHSP70-5在热处理下下调，在干旱胁迫下上调。此外，一些重复基因的表达部分冗余，而其他基因则表现出功能多样性。我们的结果表明HSP70基因家族在干旱和热胁迫条件下的番茄中具有多种作用，并为进一步研究HSP70基因家族功能，特别是在干旱和热胁迫下的功能打开了大门。
