玉米弯孢叶斑病菌Clg2基因克隆、序列特征和不同发育阶段表达分析

摘要

异源三聚体 G 信号通路在调控植物病原真菌的形态、侵染结构形成和致病力等方面具有重要作用。本研究根据玉米弯孢叶斑病菌新月弯孢全长 cDNA 文库中的 EST 序列，克隆获得一个含1074 bp 开放读码框（ORF）Gα基因。该基因包含5个外显子和4个内含子，编码357个氨基酸，被命名为Clg2。通过序列比对和进化树分析，证明 Clg2蛋白具有 Gα蛋白结构特征和保守序列区，与小麦黄斑叶枯病菌（Pyrenophora tritici-repentis Pt-1C-BFP）和大斑刚毛座腔菌（Setosphaeria turcica ）中的 Gα蛋白相似性高达96％和97％，处于同一分支。采用实时荧光定量 PCR 技术分析了Clg2基因在病菌不同发育阶段的表达水平，显示在菌丝中表达水平最低，在分生孢子中表达量最高，暗示Clg2基因在病菌分生孢子形成期起重要作用。上述结果将为开展 Clg2蛋白功能研究奠定基础。%G protein signal pathway plays an important role in regulation of morphology,infection structure for-mation and virulence of the plant pathogen.To study the regulation mechanism of G protein in Curvularia lunata , a Gα gene with an ORF of about 1 074 bp was cloned based on an EST from the full-length cDNA library,which was named as Clg2.This gene included 5 exons and 4 introns,and encoded 357 amino acids through comparing ge-nomic DNA and cDNA sequences.Sequence alignment and phylogenetic analysis showed that this protein con-tained the characteristic conserved sequence like that of other Gα proteins,and shared 96% and 97% similarity with Gαprotein from Pyrenophora tritici-repentis Pt-1C-BFP and Setosphaeria turcica ,respectively.Expression of Clg2 in different development stages of C .lunata was analyzed by fluorescence-quantitative RT-PCR.These re-sults showed that the highest expression level was found in conidia,whereas the lowest in hyphae,which suggested that Clg2 might play a vital role in the formation of conidia,which may provide additional information for the study of the function of Clg2.