葫芦fw3.2基因的克隆及表达差异分析

Isolation and Expression Analysis of Gene fw3.2 in Lagenaria Siceraria

作为调控果实重量的主效QTLs(quantitative trait loci)之一,fw3.2可以通过促进细胞分裂影响果实大小.尽管fw3.2基因已在多种植物中被识别和分离,但在葫芦中的研究却未见报道.本研究首次对葫芦(Lagenaria siceraria)的fw3.2进行克隆和测序,该基因全长1980bp,由2个外显子和1个内含子组成,编码534个氨基酸.同时,在果实大小不同的两个葫芦变种之间fw3.2基因编码区完全一致.系统发育和同源比对分析显示,该基因属于CYP78A5基因家族,与甜瓜和黄瓜中同源基因的序列一致度可高达92%,在葫芦科中高度保守.此外,该基因在2个葫芦变种的叶、花和果实中均有表达,且在果实增长初期,小葫芦中表达强于大葫芦.这种表达态势可能和两种葫芦的细胞分裂高峰期不同有关.本研究为进一步揭示葫芦果型变异的分子机制提供了必要的科学依据.

As one of major QTLs （quantitative trait loci） , fzw3.2 is usually considered to be an impor tant gene to affect fruit size through promoting cell division. Although the fw3.2 gene has been identified and isolated in many plants, studies in the gourd have not been reported. In this study, the fw3.2 of Lage naria siceraria is cloned and sequenced for the first time. The gene is 1980 bp in length and composed 2 ex ons and 1 intron, encoding 534 amino acids.At the same time, the coding region of the fw3.2 in two gourd varieties, which have small and large fruits, are consistent completely. Phylogenetic and homologous corn parison show that the fw3.2 belongs to CYP78A5 gene subfamily, and it is highly conserved in the Cucur bitaceae, which shars 92% sequence identities with their homologous genes in melon and cucumber. In ad dition, the fw3.2 genes are expressed in leaves, flowers and fruits of both gourd varieties, but in the early stage of fruit growth, the expression level of the gene in the small gourd is always stronger than that of in the large one. This expression pattern may be related to different time of cell division peak of two gourds. Our present study provides some basic data for further revealing the molecular mechanism of fruit size vat iation in gourds.