The MYB Transcription Factor Negatively Regulates Resistance in Soybean.

Phytophthora root rot is a devastating disease of soybean caused by . However, the resistance mechanism is not yet clear. Our previous studies have shown that enhances sensitivity to in soybean, and is downregulated in the transcriptome analysis of -overexpressing transgenic hairy roots. Here, was significantly induced by in susceptible soybean, and the overexpressing of enhanced sensitivity to the pathogen, while silencing enhances resistance to , indicating that is a negative regulator of . Moreover, the jasmonic acid (JA) content and JA synthesis gene was highly upregulated in -silencing roots and highly downregulated in overexpressing ones, suggesting that could respond to through the JA signaling pathway. Furthermore, the expression of several pathogenesis-related genes was significantly lower in -overexpressing roots and higher in -silencing ones. Additionally, we screened and identified the upstream regulator GmbHLH122 and downstream target gene of GmMYB78. GmbHLH122 was highly induced by and could inhibit expression in resistant soybean, and GmMYB78 was highly expressed to activate downstream target gene transcription in susceptible soybean. In conclusion, our data reveal that triggers soybean sensitivity to by inhibiting the JA signaling pathway and the expression of pathogenesis-related genes or through the effects of the GmbHLH122-GmMYB78- cascade pathway.