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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 oxysporumf.sp.cubenserace4 (Focr4), a Fusarium oxysporum f.sp.cubenserace4 (Focr4), is the most destructive soil disease causing banana fusarium wilt. Its pathogenic mechanism remains unclear. The biological phenotype of mutant Focr4-1562 and its inactivation gene knock-in △ Focr4-1562, which had been severely attenuated by T-DNA insertion of wild-type strain Focr4-193-6, was obtained Study. The results of cellophane penetration test, inoculation of leaves and inoculation of inoculum showed that the inserted mutants and the knock-out can not penetrate the cellophane growth, there was no obvious lesion and necrosis of bulbar vascular bundle in leaf inoculation and root inoculation ; Wild-type strains were able to penetrate the cellophane growth, the obvious manifestations of the leaves inoculation site, inoculation of the roots and corms vascular symptoms of browning. T-DNA insertion mutant Focr4-1562 and its gene knockout △ Focr4-1562 pathogenic phenotype, initially identified as severely attenuated pathogenic. The results of vegetative growth and morphological observation showed that the optimal growth temperature of wild-type, inserted mutants and their knockout were at 28 ℃, and the optimum growth pH value was 7.0-8.0. The mutants and their knockout There was no significant change in the sporozoite morphology of Focr4-193-6 compared with wild type Focr4-193-6, but the sporulation of △ Focr4-1562 was decreased, and the resistance of insertional mutants and their knockouts to cell wall degrading enzymes was greatly increased Enhanced, indicating that the pathogenicity of the knocked out genes associated with Focr4-193-6 conidia generation and cell wall formation.