紫萁油菜素内酯受体cDNA的克隆及其进化分析

Cloning and Phylogenetic Analysis of Brassinosteroid Receptors in Osmunda japonica

油菜素内酯(Brassinosteroid,BR)可促进植物生长发育并在植物木质部形成中具有重要作用。BR受体是BR发挥作用的必要桥梁而其仅存在于维管植物中,因此以蕨类植物紫萁为材料研究BR受体的功能,对研究BR受体与维管组织的发生之间的关系具有重要作用。利用本地BLAST搜索紫萁转录组数据发现一个与拟南芥BR受体序列高度同源的基因,通过5′及3′RACE-PCR获得其全长c DNA序列;利用Clustal X 1.8将其与拟南芥BR受体的蛋白序列进行多重序列比对;在Phytozome中搜索已测序物种的BR受体同源蛋白并利用MEGA5.2.1软件构建进化树。研究发现该蛋白与拟南芥BRL2(Brassinosteroid Insensitive 1 like 2)序列最相似,因此命名为Os JBRL2。Os JBRL2长3 546 bp,编码1 182个氨基酸,具有BR受体典型的亮氨酸重复序列,岛屿及激酶结构域,在已发现的BR受体中最古老。

BRs（Brassinosteroids） can stimulate plant growth and play an important role in xylem differentia-tion. BRs must combine with BR receptors which are limited to the vascular plants to switch the signaling pathway. Studying the BR receptors function of Osmunda Japonica is important to understand the relationship between the BR receptors and the vascular development. The transcriptome database analysis of the Osmunda japonica using local BLAST showed a sequence with high similarity to the Arabidopsis BR receptors.Then the full-length c DNA was extended by 5′ and 3′ RACE-PCR. Multiple alignment was performed between the sequence and the Arabidopsis BR receptors by using Clustal X 1.8. Then the sequence was used to search the BR receptor homologs in Phytozome 9 database by BLASTP program. All the searched se-quences were used to construct a phylogenetic tree by using MEGA 5.2.1. The result showed that the BR re-ceptor in Osmunda Japonica was more similar to At BRL2（Brassinosteroid Insensitive 1 like 2）, so it was named Os JBRL2. The Os JBRL2 was 3 546 bp and encoded 1 182 amino acids. It contains conserved domains of BR receptors, including the LRRs（leucine-rich repeats）, ID（Island Domain） and kinase domain.The Os JBRL2 maybe the oldest one among the founded BR receptors.