Abstract
N-acylhomoserine lactone (AHL) quorum-sensing signal molecules of bacteria are involved in regulating the inhibition effect of biocontrol agents on several plant diseases. However, the direct inhibition effect of AHL on pathogens and the molecular mechanism of inhibition remain unclear. Phytophthora root rot (PRR) of soybean, caused by
Phytophthora sojae
, is a devastating oomycete disease in soybean production. To investigate the application potential of AHL in PRR control, zoospore chemotaxis, oospore formation, mycelial growth, and pathogenicity in
P. sojae
responding to AHL were determined. The transcriptome of
P. sojae
in response to AHL was also analyzed. The key differentially expressed genes were quantitatively verified by qRT-PCR. We found that N-decanoyl-L-homoserine lactone (C10-HSL) was the most abundant AHL in the fermentation broth biocontrol strain
Pseudomonas mandelii
. C10-HSL repels
P. sojae
zoospores, inhibits
P. sojae
mycelial growth and oospore formation, and alleviates the pathogenicity of
P. sojae
. The inhibition effect was regulated mainly by nitrogen metabolism, efferocytosis, glycolysis/gluconeogenesis, and carbon metabolism pathways.
P. sojae
cell structures could disrupt and carbohydrate utilization could interfere with the response process. This result reveals that C10-HSL acts as a cross-kingdom signaling molecule to inhibit
P. sojae
and control PRR.