Gao Wenrui, Li Decui, Fan Xiaoxue, Sun Yanjun, Han Bing, Wang Xiansheng, Xu Gang
Institute of Vegetable Crop, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014 Jiangsu China.
Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing, 210014 Jiangsu China.
3 Biotech. 2020 Jul;10(7):302. doi: 10.1007/s13205-020-02293-3. Epub 2020 Jun 12.
Expansins are plant cell-wall loosening proteins involved in cell enlargement, adaptive responses to environmental stimuli, and various developmental processes. Although expansins have been characterized in many plant species, little is reported on this family in watermelon. In this study, 30 expansin genes in the watermelon genome (ClEXPs) were identified. These genes which were divided into four subfamilies (7 ClEXLAs, 2 ClEXLBs, 18 ClEXPAs, and 3 ClEXPBs) are unevenly distribute on 10 of 11 watermelon chromosomes. Chromosome mapping suggested that tandem duplication events may have played important roles in the expanding of watermelon expansins. Gene structure and motif identification revealed that same subfamily and subgroup have conserved gene structure and motif. Detection of -acting elements revealed that ClEXPs gene promoter regions were enriched with light-responsive elements, hormone-responsive, environmental stress-related, and development-related elements. Expression patterns of ClEXPs were investigated by qRT-PCR. The results showed that expression patterns of 15 ClEXP genes differed in three tissues. Through our own and public RNA-seq analysis, we found that ClEXPs had different expression patterns in fruit flesh, fruit rind, and seed at various developmental stages, and most of ClEXPs were highly responsive to abiotic and biotic stresses. Remarkably, 7 ClEXPs (, , , , , and ) exhibited positive response to at least three kinds of stresses, suggesting that they might play important roles in the crosstalk of stress signal pathways. The results of this study provide useful insights for the functional identification of expansin gene family in watermelon.
扩展蛋白是一类参与细胞膨大、对环境刺激的适应性反应以及各种发育过程的植物细胞壁松弛蛋白。尽管扩展蛋白已在许多植物物种中得到表征，但关于西瓜中该家族的报道却很少。在本研究中，在西瓜基因组中鉴定出了30个扩展蛋白基因（ClEXPs）。这些基因分为四个亚家族（7个ClEXLAs、2个ClEXLBs、18个ClEXPAs和3个ClEXPBs），不均匀地分布在11条西瓜染色体中的10条上。染色体定位表明串联重复事件可能在西瓜扩展蛋白的扩增中发挥了重要作用。基因结构和基序鉴定表明，同一亚家族和亚组具有保守的基因结构和基序。对顺式作用元件的检测表明，ClEXPs基因启动子区域富含光响应元件、激素响应元件、环境胁迫相关元件和发育相关元件。通过qRT-PCR研究了ClEXPs的表达模式。结果表明，15个ClEXP基因在三种组织中的表达模式不同。通过我们自己的和公开的RNA-seq分析，我们发现ClEXPs在果实发育的各个阶段在果肉、果皮和种子中具有不同的表达模式，并且大多数ClEXPs对非生物和生物胁迫高度响应。值得注意的是，7个ClEXPs（、、、、、和）对至少三种胁迫表现出阳性反应，表明它们可能在胁迫信号通路的相互作用中发挥重要作用。本研究结果为西瓜扩展蛋白基因家族的功能鉴定提供了有用的见解。
