摘要
尖镰孢古巴专化型4号小种Fusarium oxysporumf.sp.cubenserace4(Focr4)是引起毁灭性土传病害香蕉枯萎病的危害性最大的小种,至今其致病机理尚不清楚。对已获得的野生型菌株Focr4-193-6经基因T-DNA插入引起致病性严重减弱的突变体Focr4-1562及其插入失活基因的敲除子△Focr4-1562的生物学表型进行了研究。玻璃纸穿透试验、活体叶片接种及根部接种致病性测定的结果表明,插入突变体和敲除子不能穿透玻璃纸生长,叶片接种和根部接种未见有明显病斑和球茎维管束变褐症状;野生型菌株则能穿透玻璃纸生长,叶片接种部位表现明显症状,被接种根部和球茎的维管束表现变褐症状。T-DNA插入突变体Focr4-1562和其基因敲除子△Focr4-1562的致病性表型一致,初步鉴定为致病性严重减弱。营养生长及形态学观察结果表明,野生型、插入突变体及其敲除子的最适生长温度均在28℃,最适的生长pH值为7.0-8.0之间,插入突变体及其敲除子的孢子形态与野生型Focr4-193-6相比并没有显著的变化,但敲除子△Focr4-1562的产孢量降低,插入突变体及其敲除子对细胞壁降解酶的抗性大大增强,说明被敲除的致病相关基因与Focr4-193-6分生孢子产生及细胞壁的形成有关。
Fusarium oxysporum f. sp. cubense race 4 （Focr4） is considered as one of the most destructive pathogens of the world distributed soil-borne banana. Its pathogenesis has not been clearly understood. The pathogenicity of mutant Focr4-1562 was significantly weakened after T-DNA insertion in its gene sequence. The inserted exogenous gene caused changes in functions of some genes in the AFocr4-1562. By means of cellophane penetration test as well as pathogenic test by inoculating live leaves and roots, changes in pathogenic phenotype of the mutant Focr4-1562 and △Focr4-1562 were compared with the wild type Focr4, The mutant Focr4-1562 and △Focr4-1562 could not grow through cellophane, and didn＇t cause any disease spots and brown coloration in corm vascular bundle. The results showed that the optimum growth temperature of the wild type Focr4, Focr4-1562 and △Focr4-1562 were all at 28℃, and their optimum growth pH was 7.0 to 8.0. No evident difference was found in their spore morphology, but the sporulation of △Focr4-1562 was obviously delayed, and its sporulation capacity was significantly decreased. The Focr4-1562 and △Focr4-1562 were more resistant to cell wall degrading enzyme than the wild type Focr4-193-6. It is concluded that the knockout of the pathogenic gene is responsible for conidial production and cell wall formation of the wild type Focr4-193-6.
出处
《菌物学报》
CAS
CSCD
北大核心
2012年第4期584-592,共9页
Mycosystema
基金
国家自然科学基金(No.30860160)
国家公益性行业(农业)科研专项课题(No.200903049-2)
海南大学"211工程"建设项目
海南大学环境与植物保护学院研究生创新平台
