Maize and Common Bean Seed Exudates Mediate Part of Nonhost Resistance to Phytophthora Sojae before Infection

Abstract

Purpose: Phytophthora sojae does not infect the nonhost maize (Zea mays L.) but could infect the nonhost common bean (Phaseolus vulgaris L.). Soybean seed exudates participate in mediating host resistance to P. sojae before infection. This study aimed to elucidate the role of nonhost seed exudates in mediating nonhost resistance to P. sojae before infection. Methods: The response behavior of P. sojae zoospores to the seed exudates was determined using an assay chamber and a concave slide, and the proteomes of P. sojae zoospores treated with the seed exudates were analysed with the tandem mass tag (TMT) method. The key proteins were quantified by parallel reaction monitoring (PRM).Results: Maize seed exudates exerted a repellent effect on zoospores, whereas common bean seed exudates did not exhibit any attraction to zoospores but could dissolve the cysts. The key proteins related to zoospores chemotaxis showed no significant changes in response to maize seed exudates, but the key proteins in arachidonic acid pathway were downregulated and controlled the repellent behavior of zoospores. Proteins protecting the cell membrane structure were significantly downregulated in zoospores responding to common bean seed exudates, which confirmed the bacteriolytic effect of common bean seed exudates on cysts. Conclusion: Maize and common bean seed exudates mediate part of the nonhost resistance via different mechanisms prior to P. sojae infection. The immune of maize to P. sojae is due to the repellent effect of maize seed exudates on zoospores. Common bean seed exudates participate in mediating nonhost resistance by dissolving cysts.

Isoflavone phytoalexins in root exudates participate in mediating the resistance of common bean Phaseolus vulgaris to Phytophthora sojae

“…Kievitone, phaseollin and phaseollidin have extensive antimicrobial activities and inhibit mycelial growth of Aphanomyces euteiches (Smith, 1976), C. lindemuthianum (Bailey & Deverall, 1971) and Botrytis cinerea (Perrin et al, 1974), respectively. It is reported that seed exudates mediate resistance of common bean to P. sojae (Zhang et al, 2022). This study further confirmed that common bean root exudates contain three important phytoalexins, kievitone, phaseollin and phaseollidin, and that these phytoalexins can be induced by P. sojae infection, having a significant inhibition effect on P. sojae.…”

“…It is reported that seed exudates mediate resistance of common bean to P . sojae (Zhang et al, 2022). This study further confirmed that common bean root exudates contain three important phytoalexins, kievitone, phaseollin and phaseollidin, and that these phytoalexins can be induced by P .…”

“…We found that common bean seed exudates inhibited the expression of P. sojae proteins that protect cell membrane structure and participate in the degradation of the apoptosis signal glutathione (Zhang et al, 2022). We also found that the hypersensitive response (HR) was produced after common bean hypocotyls were inoculated by P. sojae, which was attributed to the induction of phaseollidin and glyceollin at the infection site; both phaseollidin and glyceollin strongly inhibited mycelial growth and oospore formation of P. sojae (Bi et al, 2022).…”

“…We found that common bean seed exudates inhibited the expression of P . sojae proteins that protect cell membrane structure and participate in the degradation of the apoptosis signal glutathione (Zhang et al, 2022). We also found that the hypersensitive response (HR) was produced after common bean hypocotyls were inoculated by P .…”