忻州市红芸豆根腐病病原菌鉴定和致病性分析及其对红芸豆植株抗氧化系统的影响

Identification and pathogenicity analysis of red kidney bean root rot pathogens in Xinzhou City and their effects on the antioxidant system of red kidney bean plants

中文关键词:红芸豆  根腐病  镰刀菌  致病性  抗氧化系统

keywords:red kidney bean  root rot disease  Fusarium  pathogenicity  antioxidant system

中文摘要:为明确山西省忻州市红芸豆Phaseolus vulgaris根腐病病原菌及其致病性和对红芸豆植株抗氧化系统的影响，采用组织分离法从感根腐病红芸豆植株分离病原菌，结合形态学特征和分子生物学技术对其进行鉴定，利用混合接种法对其致病性进行分析，并检测其对红芸豆植株抗氧化系统指标超氧化物歧化酶（superoxide dismutase，SOD）、过氧化氢酶（catalase，CAT）、过氧化物酶（peroxidase，POD）以及丙二醛（malondialdehyde，MDA）的影响。结果表明：共分离获得3类形态学特征不同的真菌菌株，结合分子生物学鉴定结果，确定红芸豆根腐病病原菌主要有3种，分别为尖孢镰刀菌Fusarium oxysporum、芬芳镰刀菌F.redolens和腐皮镰刀菌F.solani，其中尖孢镰刀菌的分离频率最高，占分离镰刀菌总数的56.25%。3种镰刀菌混合接种处理对红芸豆植株的致病性比各自单独接种处理更强，病情指数为82.67，其次为接种尖孢镰刀菌FU13和芬芳镰刀菌FU9处理，病情指数分别为69.33和61.33，表明尖孢镰刀菌和芬芳镰刀菌是忻州市红芸豆根腐病的优势致病菌。尖孢镰刀菌FU13、芬芳镰刀菌FU9、腐皮镰刀菌FU4分别单独接种和3株菌株混合接种处理后，红芸豆植株叶片中SOD和CAT活性于第7天达到峰值，分别为421.09~689.40 μg·g-1·min-1和101.87~121.19 μg·g-1·min-1，较不接种对照分别增加了33.12%~117.94%和10.13%~31.02%；POD活性则于第21天达到峰值，为950.4~2257.2 μg·g-1·min-1，较不接种对照增加了10.56%~162.59%，其中混合接种处理的峰值显著高于单独接种镰刀菌处理；MDA含量显著升高，在第21天时增幅最大，为7.17~13.75 nmol/g，较不接种对照增加了16.21%~122.85%，随后仍逐渐上升，且混合接种处理显著高于单独接种处理，表明镰刀菌侵染对红芸豆植株造成了持续性伤害，SOD、CAT、POD对其均有响应。

Abstract:To identify the pathogens causing root rot in red kidney bean Phaseolus vulgaris in Xinzhou City, Shanxi Province, and to assess their pathogenicity and effects on the antioxidant system of red kid ney bean plants, microbial candidates were isolated from infected root tissues using the tissue isolation method. The species were identified based on their morphological and molecular biological characteristics, and their pathogenicity was analyzed using a mixed-inoculation method. The impact of these pathogens on the activities of antioxidative enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) as well as the malondialdehyde (MDA) content in red kidney bean plants were also tested. The results showed that three fungal strains with different morphological features were isolated. Molecular identification confirmed that the three main pathogens of red kidney bean root rot were Fusarium oxysporum, F. redolens, and F. solani, with F. oxysporum being the most prevalent, accounting for 56.25% of the total isolates. The co-mixed inoculation of these three Fusarium species exhibited higher pathogenicity than any single inoculation, with a disease index of 82.67. Single inoculations of F. oxysporum and F. redolens yielded disease indices of 69.33 and 61.33, respectively, suggesting that F. oxysporum and F. redolens are the dominant causal agents of red kidney bean root rot in Xinzhou City. After inoculation with F. oxysporum FU13, F. redolens FU9, F. solani FU4 or the mixture of these three pathogens, the activities of SOD and CAT in the leaves peaked on day 7 at 421.09-689.40 μg·g^-1·min^-1 and 101.87-121.19 μg·g^-1·min^-1, respectively, which were 33.12%-117.94% and 10.13%-31.02% higher than the control. POD activity peaked at 950.4-2 257.2 μg·g^-1·min^-1 on day 21, showing increases of 10.56%-162.59% compared with the control. The peak value of the mixed inoculation treatment was significantly higher than that of single inoculation treatments. The content of MDA was significantly elevated, with the largest increases observed on day 21, reaching 7.17-13.75 nmol/g, which was 16.21% -122.85% higher than the control. MDA content continued to increase gradually after day 21, and the mixed inoculation treatment showed significantly higher levels than single inoculation treatments. These results indicate that Fusarium infection leads to persistent injury and elicits responses from SOD, CAT, and POD in red kidney bean plants.