旁路氧化作用对嘧菌酯抑制辣椒炭疽菌孢子萌发和菌丝生长的影响

Impact of alternative respiration on response of conidial germination and mycelial growth of Colletotrichum capsici to azoxystrobin

研究表明,旁路氧化作用能够降低辣椒炭疽菌对嘧菌酯的敏感性。离体培养条件下,旁路氧化在辣椒炭疽菌野生菌株的孢子萌发中提供大于95倍生理功能的补偿作用;在菌丝生长中提供20 ～35倍的补偿作用。但在接种前用嘧菌酯处理辣椒,旁路氧化作用并不明显,嘧菌酯对辣椒炭疽病有良好的保护、治疗、铲除和抗产孢作用。用嘧菌酯处理过的病斑产生的分生孢子萌发活力和致病力下降。炭疽菌离体下的菌丝耗氧率测定表明,10μg/mL嘧菌酯处理1 h对菌丝呼吸耗氧有良好的抑制作用,其抑制效果随药剂浓度提高而略有增加。随处理时间延长,药剂对菌丝耗氧的抑制作用下降,但仍然抑制菌丝生长。研究证明:延长处理时间,呼吸作用对药剂的敏感性下降的机理不是因为旁路氧化途径增强,也不是因为基质中药剂效力的下降,而是存在其它机制。

Sensitivity of Colletotrichum capsici to azoxystrobin could be decreased by the induction of alternative respiration. In the absence of a host, alternative respiration provided a more than 95-fold rescue potential from azoxystrobin during the germination of conidia derived from four wild-type isolates of C. capsici. And for mycelial growth, the rescue potential was 20 - 35-fold. However, pronounced effect of alternative respiration during conidial germination was not apparent when capsicums were treated with azoxystrobin prior to inoculation with conidia suspension. Azoxystrobin was possessed of excellent protective, curative, eradicative and antisporulant activity. The germination vitality and pathogenicity of conidia derived from the lesions under azoxystrobin treatment were decreased, but the sensitivity to azoxystrobin changed little. Oxygen consumption test of mycelia showed that azoxystrobin strongly inhibited mycelial respiration after 1 h of the treatment at 10 μg/mL and the effect became stronger when the concentration was increased. As treatment time went on, the respiration inhibition on the mycelia decreased, while the mycelium growth was still inhibited strongly. Results showed that the sensitivity decrease of mycelium respiration to azoxystrobin was not caused by induction of alternative respiration or degrade of the fungicide in medium.