Induced Defense Response in Soybean to Sclerotinia sclerotiorum Using Wuyiencin from Streptomyces albulus CK-15

Abstract

Sclerotinia sclerotiorum (Lib) de Bary, a destructive fungal pathogen with an extensive host range, causes major economic losses to crop production activities globally. Streptomyces spp. produce secondary metabolites with diverse structures and biological activities with potential applications in the control of crop disease. This study explored the potential application of wuyiencin, a secondary metabolite of Streptomyces albulus CK-15, to induce defense responses in soybean against S. sclerotiorum. Lesion size was reduced by nearly 60% in wuyiencin-treated soybean plants compared with plants infected with S. sclerotiorum only in greenhouse experiments. Wuyiencin induced callose deposition at 6 h postinoculation and increased reactive-oxygen-scavenging enzyme activities, including superoxide dismutase, catalase, and peroxidase. Moreover, wuyiencin inoculated before S. sclerotiorum infection significantly increased polyphenol oxidase, phenylalanine ammonia lyase, chitinase, and β-1,3-glucanase activity, suggesting their involvement in soybean defense responses to S. sclerotiorum. Further, qRT-PCR results showed expression levels of the hormone signaling markers CO11, MYC2, PR4, PR1, NPR1, and ERF1 were upregulated in infected leaves treated with wuyiencin.