不同抗性蚕豆品种根系分泌物对枯萎病菌的化感作用及根系分泌物组分分析

Allelopathic effects and components analysis of root exudates of faba bean cultivars with different degrees of resistance to Fusarium oxysporum

  • 摘要: 蚕豆枯萎病是土传病害, 其发生与蚕豆根系分泌物有密切关系。本文以3个枯萎病不同抗性蚕豆品种--'89-147'(高抗)、'8363'(中抗)和'云豆324'(感病)为材料, 通过水培试验收集根系分泌物, 测定根系分泌物对镰刀菌孢子萌发和菌丝生长的影响, 分析对枯萎病表现出不同抗性的蚕豆品种根系分泌物中糖、氨基酸和有机酸的含量, 分离鉴定了根系分泌物中氨基酸和有机酸的组分。结果表明, 抗病品种的根系分泌物抑制了尖孢镰刀菌的孢子萌发和菌丝生长, 在加入5 mL中抗品种根系分泌物时, 显著促进尖孢镰刀菌孢子萌发, 但对菌丝生长无显著影响; 而在加入1 mL感病品种根系分泌物时, 就能显著促进尖孢镰刀菌孢子萌发和菌丝生长。不同抗性蚕豆品种根系分泌物中氨基酸总量和总糖含量随抗性的降低而升高, 有机酸分泌总量则随蚕豆品种对枯萎病的抗性增加而升高。感病品种和中抗品种中检出15种氨基酸, 而高抗品种中检出14种, 组氨酸只存在于中抗品种中, 脯氨酸仅在感病品种中检出, 3个蚕豆品种根系分泌物中均未检出精氨酸。蚕豆根系分泌物中天门冬氨酸、谷氨酸、苯丙氨酸、酪氨酸和亮氨酸含量高, 可能会促进枯萎病的发生, 而蛋氨酸、赖氨酸和丝氨酸含量高可能抑制枯萎病发生。酒石酸仅在抗病品种中存在, 根系分泌物中有机酸种类丰富, 有助于提高蚕豆对枯萎病的抗性。蚕豆对枯萎病的抗性不同, 根分泌物对镰刀菌孢子萌发和菌丝生长的影响也不同, 而这种抗病性差异与蚕豆根系分泌物中糖、氨基酸、有机酸的含量和组分密切相关。

     

    Abstract: Fusarium wilt is one of the most common and destructive soil-borne fungal diseases of faba bean because of continuous monocropping. It has been responsible for severely reduced yield, quality and production of faba bean, especially in Yunnan Province. Numerous studies on soil-borne diseases have mainly focused on changes in soil nutrients, enzyme and microbe. Little has remained known about the relationship between root exudates and soil-borne diseases. In fact, there has been less report confirming the occurrence of fusarium wilt in different cultivars of faba bean affected by different faba bean root exudates. The objectives of this study were to compare the differences in root exudates contents and components of different cultivars of faba bean. The study also aimed to lay the basis for further studies on resistance mechanism of faba bean fusarium wilt, which could in turn lay the basis for ecological control of faba bean fusarium wilt. Cultivars of different resistances to fusarium wilt were used in the experiment - '89-147' (high resistant cultivar), '8363' (medium resistant cultivar) and 'YD324' (susceptible cultivar). Root exudates of the three cultivars of faba bean were collected in nutrient solution cultures. The effects of faba bean root exudates on spore germination and mycelia growth of Fusarium oxysporum f. fabae were determined using the culture medium method. The contents and components of organic acids were identified by HPLC while free amino acids were identified by amino acid analyzer. The content of soluble sugar was tested by anthrone colorimetry. The results suggested that compared with the control, root exudates of resistant cultivars inhibited spore germination and mycelia growth of F. oxysporum. Exudates of medium resistant cultivar promoted mycelia growth with the addition of 5 mL of root exudates, it otherwise had no significant effect on mycelia growth. Exudates of susceptible cultivar promoted spore germination and mycelia growth with the addition of 1 mL of root exudates. Total content of free amino acids and soluble sugar increased while organic acids decreased with increasing resistance of the three faba bean cultivars to fusarium wilt. Fifteen types of amino acids were detected in root exudates of medium resistant and susceptible faba bean cultivars while fourteen types of amino acids were detected in root exudates of high resistant faba bean cultivars. Histidine was found only in root exudates of medium resistant faba bean cultivar while praline was only in root exudates of susceptible faba bean cultivar. Arginine was not found in root exudates of the three faba bean cultivars. The occurrence and development of faba bean fusarium wilt were enhanced when the contents of aspartic, glutamate, phenylalanine, tyrosine and leucine in root exudates were high. Faba bean fusarium wilt was inhibited when the contents of methionine, lysine and serine in root exudates were high. Tararic was detected only in root exudates of high resistant cultivar. The richness of organic acid species in root exudations enhanced faba bean resistance to fusarium wilt. Root exudates of different resistance faba bean cultivars had different effects on F. oxysporum. These differences were related to the contents and components of soluble sugars, free amino acids and organic acids in root exudates of different faba bean cultivars.

     

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