Cloning and diversity of fga1 from fusarium oxysporum f. sp. cubense | 香蕉枯萎病菌fga1基因克隆及其多样性研究

chinois. 摘　　要：尖孢镰刀菌古巴专化型（Fusarium oxysporum f.sp.cubense）是引起香蕉枯萎病的病原菌,其中1号生理小种（Foc1）侵染粉蕉品种,而4号生理小种（Foc4）则危害粉蕉和香牙蕉品种。为探讨Foc1和Foc4致病性差异的遗传基础,本文根据已经公布的番茄枯萎病菌（Fusarium oxysporum f.sp.radicis-lycopersici）基因组序列,利用同源克隆的方法,分离到一个重要的致病基因――fga1,比较了不同区域Foc1和Foc4fga1基因cDNA和gDNA序列的差异。结果表明Foc1中fga1基因保守性很强,含有3个内含子和4个外显子,蛋白产物含353个氨基酸;所研究材料中Foc4fga1基因80%都有2个转录本,小转录本与Foc1fga1一致,而大转录本第三个内含子由于可变性剪切使得其成为外显子,预测编码一个372个氨基酸的多肽;来自海南三亚的Foc1和Foc4的fga1基因gDNA和cDNA长度分别为1286bp和1092bp,相似性均为100%。

anglais. Fusarium oxysporum f. sp. cubense is the causal agent of Fusarium wilt of banana, while Race 1 （Foc1） infects the Fenjiao cultivars, and beside Fenjiao, Race 4 （Foc4） also infects Cavendish bananas. Basing on the published genomic sequences of Fusarium oxysporum f. sp. radicis-lycopersici, an important pathogencity gene-fga1 was isolated using the method of homology-based cloning. Sequences of Foc1 and Foc4 from different regions were aligned. The results were shown that the full-length of gDNA of Foc1 and Foc4 from Hainan is 1 286 bp, and their sequence homology is 100%. The sequence of Foc1 fga1 was conserved, including 4 extrons and 3 introns, which encoded a protein with 353 amino acides. However, 80% of Foc4 fga1 had two transcripts, and the smaller one was same to Foc1 fga1, while the larger one encoded a polypeptide with 372 amino acids due to an alternative splicing making the third intron become an extron.