Molecular Cloning and Expression Analysis of α-Expansin Genes in Anthocephalus chinensis | 团花树α扩展蛋白基因的克隆及表达分析

Chinese. 采用扩增保守区域、基因组步移及3’RACE技术，在团花树中克隆到15个d―expansin基因的cDNA序列，命名为AcEXPA2―16（GenBank注册号JF922686-JF922700），其相对应的基因组序列GenBank注册号为JF922701-JF922715。包括已知的AcEXPA1，这16个EXPA蛋白的大小及序列高度保守，包括N端的信号肽、3个外显子和2个内含子。通过氨基酸序列比对和系统进化树分析，AcEXPA1―16分为4个亚族，分别为A、B、C和D亚族。定量PCR分析显示AcEXPA1―16基因在同一组织中的表达存在冗余现象，而单个基因在不同的组织中又存在特异表达，尤其AcEXPA8在形成层中的表达水平极高。这表明AcEXPA8在木质部发生的过程中可能起到重要的作用。研究结果为在团花树中研究α-expansin基因与木质部的生长和材质的关系提供信息，并最终为林木分子育种提供潜在的候选基因。

English. Fifteen cDNAs, designated as AcEXPA2 to AcEXPA16 （GenBank accession No. JF922686 - JF922700） with the corresponding genomic DNA sequences （GenBank accession No. JF92270l -JF922715） , were isolated by amplifying conserved domain binding with genomic walking and 3＇RACE techniques from four differential tissues in Anthocephalus chinensis. The size and sequence of these ot-expansin homologues including known AcEXPA1 were highly conserved, and had the same sequence structures as an N-terminal signal peptide, three exons and two introns. Their amino acid alignment and phylogenetic analysis showed that A. chinensis ct-expansin genes were divided into four subgroups ： A, B, C and D. A real-time quantitative PCR analysis showed that the transcript level of AcEXPAI - 16 was redundant in the same tissue and tissue-specific with each gene in different tissue, especially, the transcript level of AcEXPA8 extremely high in the cambium region. These results suggest that AcEXPA8 may play an important role in xylogenesis. This study on α-expansin genes from A. chinensis will lay the foundation for studying the relationship between α-expansin genes and growth rate and wood quality of the xylem in this fast-growing tree, and finally provide potential candidate genes for tree molecular breeding.