Lu Yongen, Liu Lifeng, Wang Xin, Han Zhihui, Ouyang Bo, Zhang Junhong, Li Hanxia
Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
Mol Genet Genomics. 2016 Apr;291(2):597-608. doi: 10.1007/s00438-015-1133-4. Epub 2015 Oct 24.
Plant expansins are capable of inducing pH-dependent cell wall extension and stress relaxation. They may be useful as targets for crop improvement to enhance fruit development and stress resistance. Tomato is a major agricultural crop and a model plant for studying fruit development. Because only some tomato expansins have been studied, a genome-wide analysis of the tomato expansin family is necessary. In this study, we identified 25 SlEXPAs, eight SlEXPBs, one SlEXLA, four SlEXLBs, and five short homologs in the tomato genome. 25 of these genes were identified as being expressed. Bioinformatic analysis showed that although tomato expansins share similarities with those from other plants, they also exhibit specific features regarding genetic structure and amino acid sequences, which indicates a unique evolutionary process. Segmental and tandem duplication events have played important roles in expanding the tomato expansin family. Additionally, the 3-exon/2-intron structure may form the basic organization of expansin genes. We identified new expansin genes preferentially expressed in fruits (SlEXPA8, SlEXPB8, and SlEXLB1), roots (SlEXPA9, SlEXLB2, and SlEXLB4), and floral organs. Among the analyzed genes those that were inducible by hormone or stress treatments, including SlEXPA3, SlEXPA7, SlEXPB1-B2, SlEXPB8, SlEXLB1-LB2, and SlEXLB4. Our findings may further clarify the biological activities of tomato expansins, especially those related to fruit development and stress resistance, and contribute to the genetic modification of tomato plants to improve crop quality and yield.
植物扩张蛋白能够诱导pH依赖的细胞壁伸展和应力松弛。它们可能作为作物改良的靶点，以促进果实发育和提高抗逆性。番茄是一种主要的农作物，也是研究果实发育的模式植物。由于仅对部分番茄扩张蛋白进行了研究，因此有必要对番茄扩张蛋白家族进行全基因组分析。在本研究中，我们在番茄基因组中鉴定出25个SlEXPA、8个SlEXPB、1个SlEXLA、4个SlEXLB和5个短同源物。其中25个基因被鉴定为有表达。生物信息学分析表明，尽管番茄扩张蛋白与其他植物的扩张蛋白有相似之处，但它们在基因结构和氨基酸序列方面也表现出特定特征，这表明其具有独特的进化过程。片段重复和串联重复事件在番茄扩张蛋白家族的扩张中发挥了重要作用。此外，3外显子/2内含子结构可能构成扩张蛋白基因的基本组织形式。我们鉴定出了在果实（SlEXPA8、SlEXPB8和SlEXLB1）、根（SlEXPA9、SlEXLB2和SlEXLB4）和花器官中优先表达的新扩张蛋白基因。在所分析的基因中，包括SlEXPA3、SlEXPA7、SlEXPB1 - B2、SlEXPB8、SlEXLB1 - LB2和SlEXLB4在内的基因可被激素或胁迫处理诱导表达。我们的研究结果可能会进一步阐明番茄扩张蛋白的生物学活性，尤其是与果实发育和抗逆性相关的活性，并有助于对番茄植株进行遗传改良以提高作物品质和产量。
