Abstract Expansins are plant cell wall-loosening proteins that involve in response to environmental stimuli and various development processes. In this study, 1858 expansin members were identified in 40 plant species by using Hidden Markov Model profiles and searching against to rice and Arabidopsis expansins. They were classified into four groups: EXPA, EXPB, EXLA, and EXLB. The distribution of expansin genes in different plant species indicated that EXPA genes emerged first, and genes in EXPB, EXLA, and EXLB subgroups might be resulted from gene duplication. In wheat, there are 104 expansins, including 88 TaEXPAs, 8 TaEXPBs, and 8 TaEXLAs. Phylogenetic analysis showed that wheat, rice, and Arabidopsis expansins shared high bootstrap values, and the phylogenetic relationship of wheat expansins were supported by conserved motifs and gene structures. Evolutionary analysis of Triticum urartu, Triticum turgidum, and wheat expansin genes revealed that gene duplication, gene loss, and chromosomal rearrangement events occurred during the evolution process of wheat expansins. Three kinds of cis-elements, including development-related, hormones-related, and abiotic stress-related were identified in the promoters of wheat expansin genes. Meanwhile, the expression of wheat expansin genes is extensive and affected by abiotic stresses. Additionally, by overexpressing in Arabidopsis, the functions of TaEXPB1A in root and seed development were characterized. In combination with previous reports, these results indicated the extensive functions of wheat expansins. Shortly, this study identified wheat expansins more accurately, and extended the knowledge of expansin genes.

中文翻译：

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小麦 (Triticum aestivum L.) 扩展蛋白基因的全基因组鉴定和 TaEXPB1A 的功能表征

摘要 扩展蛋白是植物细胞壁松散蛋白，涉及对环境刺激和各种发育过程的响应。在这项研究中，通过使用隐马尔可夫模型配置文件并搜索水稻和拟南芥扩展蛋白，在 40 个植物物种中鉴定了 1858 个扩展蛋白成员。它们被分为四组：EXPA、EXPB、EXLA 和 EXLB。扩展蛋白基因在不同植物物种中的分布表明EXPA基因先出现，EXPB、EXLA和EXLB亚群中的基因可能是基因重复产生的。在小麦中，有 104 个扩展蛋白，包括 88 个 TaEXPAs、8 个 TaEXPBs 和 8 个 TaEXLAs。系统发育分析表明小麦、水稻和拟南芥扩展蛋白具有较高的引导值，并且小麦扩展蛋白的系统发育关系得到保守基序和基因结构的支持。对Triticum urartu、Triticum turgidum 和Wheat expansin 基因的进化分析表明，在小麦扩展蛋白的进化过程中发生了基因重复、基因丢失和染色体重排事件。在小麦扩展蛋白基因的启动子中鉴定出发育相关、激素相关和非生物胁迫相关3种顺式元件。同时，小麦扩展蛋白基因的表达广泛且受非生物胁迫影响。此外，通过在拟南芥中过表达，表征了 TaEXPB1A 在根和种子发育中的功能。结合之前的报道，这些结果表明小麦扩展蛋白的广泛功能。不久，这项研究更准确地鉴定了小麦扩展蛋白，并扩展了扩展蛋白基因的知识。