西瓜YUCCA基因家族鉴定及在果实成熟过程中的表达分析

Identification of YUCCA Gene Family and Expression Analysis During Watermelon Fruit Ripening Process

以栽培西瓜自交系97103为试材,测定不同发育时期果肉及果皮中游离态吲哚-3-乙酸(IAA)含量。结果显示:果实发育后期,果肉中IAA含量显著上调,果皮中IAA含量则一直保持较低水平,推测果肉中IAA可能对西瓜果实成熟与含糖量积累起重要作用。利用生物信息学手段,鉴定了西瓜生长素合成色氨酸依赖途径限速酶基因家族YUCCA,并对其在果肉与果皮组织的表达水平进行q RT-PCR检测。结果表明:西瓜YUCCA基因家族包含10个成员,所有YUCCA基因均含有FMOs保守结构域,聚类分析表明其分为两大类。基因结构分析显示这些基因包含2～5个外显子。Cl YUCCA4、Cl YUCCA6、Cl YUCCA10b及ClYUCCA10c等4个YUCCA基因在西瓜果肉中表达,且都在果实发育后期表达明显上调。Cl YUCCA4及Cl YUCCA10c在果肉与果皮中的表达量变化与IAA含量变化趋势一致,且在其他组织中几乎检测不到表达,推测其可能参与调控西瓜果实的成熟。

Using watermelon inbred line‘ 97103’ as test material,this study measured the contents of free IAA in fresh and rind at different fruit development stages. Results showed that the free IAA content in fresh was significantly increased at late fruit development stage,while that in rind was maintaining at a low level, speculating that free IAA in flesh might play an important role in fruit ripening and sugar accumulation. By bioinformatics, the paper also identified the rate-limiting enzyme gene family YUCCA of tryptophan dependent pathway for auxin synthesis,and carried out qRT-PCR detection about its expression level in fruit flesh and rind. The results indicated that there were 10 members in watermelon YUCCA family,and all had the conserved FMOs domain,watermelon YUCCA genes was divided into 2 classes by cluster analysis. Gene structure analysis showed all these genes included 2-5 exons. In addition,qRT-PCR analysis revealed that ClYUCCA4,ClYUCCA6, ClYUCCA10b and ClYUCCA10c,etc. 4 YUCCA genes were expressed in watermelon fresh and the expression was significantly up-regulated at the late fruit development stage. The expression quantity alteration of ClYUCCA4 and ClYUCCA10c were consistent with IAA content variation in fruit fresh and rind,while their expressions were barely detected in the other tissues,indicating that they might involve in the regulation of watermelon fruit ripening.