乙蒜素对苹果树腐烂病的防治效果与其作用机理

Control efficacy and action mechanism of ethylicin on apple Valsa canker

为明确乙蒜素对苹果树腐烂病的防治效果及其作用机理,采用菌丝生长速率法测定乙蒜素对苹果树腐烂病菌——苹果黑腐皮壳菌Valsa mali的抑制作用,利用离体枝条试验测定乙蒜素对苹果树腐烂病的保护和治疗效果,通过显微观察和转录组分析解析乙蒜素对病菌分生孢子萌发和菌丝生长的作用机理。结果显示:80%乙蒜素乳油对苹果树腐烂病菌菌丝生长的EC_(50)为21.93μg/mL,对苹果离体枝条的保护效果为82.20%,治疗效果为74.73%,均超过2种生物源杀菌剂对照1%申嗪霉素悬浮剂和8%宁南霉素水剂的防效,二者对苹果离体枝条的保护效果分别为48.73%和23.29%,治疗效果分别为63.51%和55.00%;且施用80%乙蒜素乳油后,乾县和洛川县苹果园的新增病株率均显著下降,对苹果树腐烂病的防治效果达到了69.17%和62.64%,表明80%乙蒜素乳剂对苹果树腐烂病有良好的防治效果。观察发现乙蒜素可明显抑制病菌分生孢子的萌发,同时引起菌丝畸形和原生质渗漏;且乙蒜素抑制了病菌营养代谢相关基因以及细胞膜合成相关基因的表达,从而干扰病菌细胞正常生长,表明乙蒜素可能通过破坏苹果树腐烂病菌的细胞壁结构和细胞膜完整性,同时抑制各种酶活性及代谢途径阻碍细胞内自身能量供应,最终达到抑菌作用。

To clarify the control efficacy and underlying the action mechanism of ethylicin against apple Valsa canker,the Petri dish-based inhibition of ethylicin on the mycelial growth of Valsa mali was assessed using the mycelial growth rate method.The protective and curative effects of ethylicin against Valsa canker were determined through detached branch experiments.Furthermore,the mechanism of ethylicin’s influence on conidial germination and mycelial growth was elucidated via microscopic observation and transcriptome analysis.The results indicated that the EC_(50) of 80%ethylicin emulsifiable concentrate(EC)against the mycelial growth of V.mali,the causal agent of apple Valsa canker,was 21.93μg/mL.The protective and curative effects of 80%ethylicin EC on detached apple branches were 82.20%and 74.73%,respectively,both exceeding those of the two bio-pesticides used as controls.Specifically,the protective and curative effects of the control fungicide,1%phenazine-1-carboxylic acid suspension concentrate,were 48.73%and 63.51%,respectively,while those of 8%ningnanmycin aqueous solution were 23.29%and 55.00%,respectively.These findings suggest that 80%ethylicin EC exhibits excellent control efficacy against apple Valsa canker.Additionally,the incidence of new diseased plants in the two tested apple orchards in Qian and Luochuan counties significantly decreased after the application of 80%ethylicin EC,and control effect of 69.17%and 62.64%against apple Valsa canker,respectively.Further observations revealed that ethylicin markedly inhibited the germination of pathogen conidia while inducing mycelial malformations and protoplasmic leakage.Moreover,ethylicin suppressed the expression of genes related to nutrient metabolism and cell membrane synthesis in the pathogen,thereby disrupting normal cellular growth.This indicates that ethylicin might exert its antibacterial effect by damaging the cell wall structure and membrane integrity of V.mali,inhibiting various enzymatic activities and metabolic pathways,and ultimately hindering the intracellular energy supply.