Wax gourd (Benincasa hispida) is an important cucurbit crop with economic and medicinal value. The myeloblastosis (MYB) gene family is one of the largest gene families in plants and regulates various biological processes, whereas the MYB gene family has not been systematically studied in wax gourd. In this study, we performed genome-wide identification of the MYB gene family in wax gourd and analyzed their phylogenetic relationship, MYB DNA-binding domain (MYB DBD), gene structure, protein motif, synteny, duplication mode and expression pattern. As a result, a total of 215 BhMYB genes (BhMYBs) were identified, belonging to four subfamilies: 1R-, 2R-, 3R- and 4R-MYB subfamilies. Genes of 1R-MYB subfamily and 2R-MYB subfamily were subdivided into different subgroups respectively. The analysis of MYB DBD, gene structure and protein motif showed that the most genes in the same subgroup have similar characteristics and the 2R-MYB genes were more conserved than the 1R-MYB genes. Interestingly, the long terminal retrotransposons (LTR-RTs) were found in the long introns of several BhMYBs. The results of synteny analysis showed that there were more syntenic gene pairs between wax gourd and other cucurbit crops, while the least number of syntenic gene pairs existed between wax gourd and rice. Gene duplication was the main reason for the expansion of the MYB gene family in wax gourd, with the transposed duplication (TRD) mode contributing more. All duplication BhMYB genes were under purifying selection pressure. Further expression analysis showed that many BhMYBs exhibited obvious tissue-specific expression and several BhMYBs were significantly induced by one or more abiotic stresses. BhMYB79 was particularly expressed in roots and significantly induced by salt, drought, cold and heat stresses, overexpression of which led to reduced tolerance to salt stress in Arabidopsis. In conclusion, our results provide a systematic analysis of wax gourd MYB gene family and facilitate the biological role study of BhMYB79 during wax gourd salt stress response process.

中文翻译：

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冬瓜 MYB 基因家族的全基因组分析及 BhMYB79 的功能分析


冬瓜 （Benincasa hispida） 是一种重要的葫芦作物，具有经济和药用价值。成髓细胞增多症 （MYB） 基因家族是植物中最大的基因家族之一，调节各种生物过程，而 MYB 基因家族尚未在冬瓜中得到系统研究。本研究对冬瓜 MYB 基因家族进行了全基因组鉴定，并分析了它们的系统发育关系、MYB DNA 结合域 （MYB DBD） 、基因结构、蛋白质基序、同线、复制模式和表达模式。结果，共鉴定出 215 个 BhMYB 基因 （BhMYB），属于四个亚家族：1R-、2R-、3R- 和 4R-MYB 亚家族。将 1R-MYB 亚家族和 2R-MYB 亚家族的基因分别细分为不同的亚组。MYB DBD 、基因结构和蛋白基序分析表明，同一亚组中大多数基因具有相似的特征，并且 2R-MYB 基因比 1R-MYB 基因更保守。有趣的是，在几个 BhMYB 的长内含子中发现了长末端反转录转座子 （LTR-RTs）。同线分析结果表明，冬瓜与其他葫芦作物之间存在较多的同线基因对，而蜡瓜与水稻之间存在最少的同线基因对。基因复制是冬瓜 MYB 基因家族扩增的主要原因，其中转座复制 （TRD） 模式的贡献更大。所有重复的 BhMYB 基因都受到纯化选择压力。进一步的表达分析表明，许多 BhMYBs 表现出明显的组织特异性表达，并且一些 BhMYBs 被一种或多种非生物胁迫显著诱导。 BhMYB79 在根中特别表达，并受到盐、干旱、冷和热胁迫的显著诱导，过表达导致拟南芥对盐胁迫的耐受性降低。综上所述，本研究结果对冬瓜 MYB 基因家族进行了系统分析，有助于研究 BhMYB79 在冬瓜盐胁迫响应过程中的生物学作用。