苯甲酸对蚕豆枯萎病菌致病力及根系组织结构抗性的影响

Effects of benzoic acid on pathogenicity of Fusarium oxysporum f. sp. fabae and tissue structure resistance of faba bean root

本研究为探讨酚酸类自毒物质苯甲酸在枯萎病菌-蚕豆(Vicia faba)互作中的作用机制,同时揭示蚕豆根系组织结构抗性对自毒物质胁迫的响应特征。采用室内培养实验研究了苯甲酸四个浓度(0、50、100、200mg·L^-1)处理对尖孢镰刀菌(Fusarium oxysporum f. sp. fabae, FOF)生长和致病力的影响;采用水培试验研究了苯甲酸处理对蚕豆幼苗生长、枯萎病发生、根系木质素含量和胼胝质沉积的影响,利用透射电镜观察蚕豆根系超微结构的变化。结果表明,苯甲酸不同浓度处理对蚕豆幼苗生长均有不同程度的抑制,且处理浓度越高,抑制效应越明显。苯甲酸胁迫显著增加蚕豆枯萎病发病率和病情指数;显著提高尖孢镰刀菌孢子萌发率和产孢量;显著提高尖孢镰刀菌的产酶和产毒能力;同时,还加剧对蚕豆根系细胞防御系统的摧毁和细胞组织结构的破坏。表明苯甲酸通过提高尖孢镰刀菌的致病力,破坏寄主的组织结构抗性,协助病原菌侵入蚕豆根系,苯甲酸与尖孢镰刀菌的协同作用加重了蚕豆连作障碍的发生。

Experiments were carried out to investigate mechanisms of phenolic acid autotoxic substance benzoic acid in interaction between Fusarium oxysporum f. sp. fabae(FOF) and faba bean, and to explore the response characteristics of root tissue structure resistance to benzoic acid stress. Four concentrations of benzoic acid were set(0, 50, 100 and 200 mg·L^-1), the effects of benzoic acid on seedling growth of faba been and pathogenicity of FOF in vitro, the effects of benzoic acid on the seedlings growth, the occurrence of Fusarium wilt, lignin content and callus deposition in faba bean roots were studied under hydroponics condition, the ultrastructure of faba bean roots by transmission electron microscopy were observed. The results showed that seedling growth was inhibited with increasing benzoic acid concentration, the higher the treatment concentration, the more obvious the inhibitory effect. Exogenously applied benzoic acid significantly increased the incidence and the disease index of faba bean Fusarium wilt, significantly increased the spore germination and sporulation, significantly increased cell wall degrading enzymes activity and mycotoxin production by FOF. Benzoic acid stress also aggravates the destruction of the defense system of faba bean root cells. It was concluded that benzoic acid increased the pathogenicity of FOF and destroyed faba bean tissue resistance, helped FOF to invade the roots of faba bean, and the synergistic effect of benzoic acid and FOF was helpful to aggravate the occurrence of continuous cropping obstacle of faba bean.