LAUSR

It has been reported that the root exudates of nonhost maize inhibits Phytophthora sojae due to the presence of benzoxazines in maize roots. To understand the concentrations of benzoxazines (Bxs) in maize root exudates and the molecular mechanism of P. sojae being inhibited, the transcriptomes of P. sojae responding to three different Bxs, DIMBOA (2,4-dihydroxy -7-methoxy-2H-1,4-benzoxazin-3(4H)-one), MBOA (6-methoxy-2- benzoxazolinone), and BOA (benzoxazolinone), were analyzed by RNA-seq method. We detected DIMBOA, MBOA and BOA with a concentration range of 7-126 μg/mL in root exudates of three tested maize cultivar (A6565, Pengyu1, and Xianyu696). DIMBOA, MBOA and BOA inhibited chemotaxis and invasiveness of P. sojae zoospores as well as mycelial growth. The inhibition was mainly regulated by endocytosis, calcium signaling pathway, PI3K-Akt signaling pathway and mTOR signaling pathway; meanwhile, the glutathione signaling pathway was activated to enhance the antioxidant capacity and efflux of toxic substances. It was speculated that endocytosis plays an important role in the response of P. sojae to Bxs, and the specific functions of genes in this pathway need to be further studied. This result provides new insights into the response mechanisms of P. sojae response to Bxs. Keywords: Phytophthora sojae, Transcriptome, Maize root exudates, Benzoxazines.