一氧化氮对果蔬采后灰霉菌生长发育及致病性的影响

Effects of nitric oxide on growth,development and pathogenicity of postharvest Botrytis cinerea on fruits and vegetables

为探讨NO的抑菌效果,以硝普钠(sodium nitroprusside,SNP)为NO供体,进行番茄活体接种试验,研究外源NO处理对采后灰霉菌Botrytis cinerea生长发育及致病性的影响,并通过胞内抗氧化相关酶活性和丙二醛(MDA)含量以及活性氧水平的检测,探讨其作用机制。结果显示,SNP的最低抑菌浓度为4 mmol/L;SNP处理灰霉菌5 h后,与对照组相比,孢子萌发率、芽管长度分别降低56%和25μm,菌丝扩展速度下降31%;胞内过氧化氢酶、过氧化物酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶活性分别下降30%、42%、38%、40%,脂氧合酶活性和MDA含量分别提高48%和67%;SNP处理灰霉菌后接种番茄6 d,发病率下降22%,病斑直径减小12 mm;胞内活性氧积累约为对照组的3倍。表明NO能够显著抑制灰霉菌的生长发育,其抑菌机制是通过诱导灰霉菌胞内活性氧积累引起氧化损伤。

The effects of nitric oxide （NO） on growth, development and pathogenicity of the postharvest pathogen Botrytis cinerea were investigated using sodium nitroprusside （SNP） as an exogenous NO donor based on experiment of inoculation of tomato. The activities of antioxidant enzymes, the content of malondialdehyde （MDA） and the level of reactive oxygen species （ROS） of B.cinerea were also tested to evaluate the inhibitory mechanism of exogenous NO. The results showed that the minimum inhibitory concentration of SNP was 4 mmol/L, which decreased the germination ratio by 56%, suppressed germ tube length by 25 μm, and reduced mycelium extension speed by 31% after 5 h. The activities of catalase （CAT）, peroxidase （POD）, ascorbate peroxidase （APX）, glutathione reductase （GR） in SNP-treated B.cinerea spores were decreased by 30%, 42%, 38%, 40%, while the activity of lypoxygenase （LOX） and the content of malondialdehyde （MDA） were increased by 48% and 67%, respectively. Compared with control, SNP treatment decreased disease incidence of tomato fruit by 22%, and reduced lesion di- ameter by 12 mm after 6 d incubation. Additionally, the accumulation of intracellular ROS was 3-fold higher than that of the control group. The results of the present study indicated that exogenous NO could inhibit the growth of B.cinerea, and the inhibitory mechanism was associated with the accumulation of ROS, resulting in oxidative damage to B.cinerea.