玉米根系分泌物中关键抑菌物质对大豆疫霉的抑菌活性

Inhibitory activity of the key antifungal substances in maize root exudates against Phytophthora sojae

间作是控制作物土传病害的有效手段,根系分泌物对病原菌生长的影响是间作具备控病效果的重要原因。本文研究了玉米根系对大豆疫霉游动孢子行为特征的影响,鉴定了玉米根组织中的关键抑菌活性物质,测定其对大豆疫霉菌丝生长和游动孢子行为的影响。结果表明,大豆与玉米间作能够显著降低大豆疫霉根腐病的发生,玉米根系和根系分泌物能够显著减弱根际大豆疫霉游动孢子的游动和根际大豆疫霉休止孢的萌发能力。通过HPLC对玉米根组织进行分析,发现玉米根组织中存在门布和苯并噻唑这两种抑菌物质,两者能显著抑制大豆疫霉游动孢子的游动和其休止孢的萌发能力;在浓度为500μg/mL时,其游动抑制率均达到100%;而萌发抑制率分别为100%和81%。同时,门布和苯并噻唑都能显著抑制大豆疫霉的菌丝生长。在浓度为500μg/mL时,其抑制率分别为100%和62.49%。综上所述,玉米根系组织中产生和分泌的门布和苯并噻唑对大豆疫霉具有抑菌活性,生产上可以利用玉米/大豆间作降低大豆疫病的危害。

Intercropping is widely used for suppression of soil-borne diseases, and the interactions between maize roots and pathogens play an important role. The present research verified the inhibition of soybean Phytophthora root rot by maize/soybean intercropping, and measured the effect of maize roots on zoospore behaviors of Phytophthora sojae. Then the antimicrobial activity of the compounds in maize root extracts were identified by HPLC, and the effect of key compounds on mycelial growth and zoospore behaviors of P.sojae was detected. The results showed that maize/soybean intercropping could significantly reduce the incidence of Phytophthora root rot. Maize roots and root exudates could significantly inhibit the activity of zoospores and the germination of cystospores of P.sojae. Moreover, MBOA(6-methoxy-2-benzoxazolinone) and BZO(benzothiazole), which were identified by HPLC, could significantly inhibit the swimming of zoospores and the germination of cystospores of P.sojae. At the concentration of 500 μg/mL, the inhibition rate of MBOA/BZO against zoospore swimming and cystospore germination reached 100%/100% and 100%/81%, respectively. At the same time, MBOA and BZO could also significantly inhibit the mycelial growth of P.sojae. At the concentration of 500 μg/mL, the inhibition rates were 100% and 62.49%, respectively. In summary, MBOA and BZO produced in the root tissues of maize had antimicrobial activity against P.sojae, which may be the main reason for inhibition of P.sojae by maize roots.Hence maize/soybean intercropping can be utilized to suppress P.sojae root rot.