增强UV-B辐射对立枯丝核菌抗氧化酶及细胞壁降解酶活性影响研究

 作为太阳光谱的一部分,到达地球表面的UV-B辐射有逐渐增加的趋势,影响地球生态系统。为揭示增强UV-B辐射对立枯丝核菌的影响,本文采用UV-B灯辐照处理病菌菌丝,并对菌丝生长、菌核形成,活性氧稳态和细胞壁降解酶进行分析。结果表明,增强UV-B辐射可导致供试菌株菌丝生长抑制、刺激菌核提早形成。处理菌株O^-·₂和H₂O₂的含量随处理时间的延长呈现不同程度的增加,其中U60处理较对照分别增加132.3%和71.3%;尽管SOD、APX、POD和CAT抗氧化酶活性也随处理时间增加而显著增强,但菌株MDA含量依然显著逐渐增加。同时,立枯丝核菌纤维素酶Cx、FPA的活性以及PG、PMG的活性均随辐射处理时间的延长而下降。此外,UV-B辐射处理菌株对高粱幼苗致病表型减弱。综上所述,增强的UV-B辐射打破立枯丝核菌体内活性氧稳态平衡,致使菌丝生长受到抑制,细胞壁降解酶活性降低,从而影响病菌致病性。

Effects of enhanced UV-B irradiation on the antioxidant enzymes and cell wall degrading enzymes of Rhizoctonia solani

As a part of the solar spectrum, the increasing UV-B radiation reached the earth′s surface affects the earth′s ecosystem. To reveal effects of enhanced UV-B radiation on Rhizoctonia solani, the growth and biochemical indexes of mycelium treated by UV-B radiation were analyzed including mycelium growth, sclerotia formation, reactive oxygen species homeostasis, and cell wall degradation enzymes. The results showed that enhanced UV-B radiation inhibited the mycelial growth, and stimulated early formation of the sclerotia. The O^-·₂ and H₂O₂ in treated mycelia increased with the increasing of treatment time. In contrast to the control sample, they increased by 132.3% and 71.3% under U60 treatment, respectively. Meanwhile, the activities of tested antioxidant enzymes including SOD, APX, POD, and CAT, increased significantly with the increase of treatment time. However, the MDA content of the tested strain still increased significantly. The activities of cellulase Cx and FPA, PG and PMG decreased with the increase of radiation treatment time. In addition, compared with the control, the pathogenic phenotype of R. solani treated with UV-B radiation resulted from sorghum seedlings was weakened. In summary, the enhanced UV-B radiation decreased the pathogenicity of R. solani to plant see-dlings. They broke the homeostasis of reactive oxygen species (ROS) in treated mycelia of R. solani, which caused mycelial growth inhibition, and the activities of the cell wall degradation enzymes decreased.