Editing of an effector gene promoter sequence impacts plant-Phytophthora interaction

Pathogen avirulence(Avr) effectors interplay with corresponding plant resistance(R) proteins and activate robust plant immune responses. Although the expression pattern of Avr genes has been tied to their functions for a long time, it is still not clear how Avr gene expression patterns impact plant-microbe interactions. Here, we selected Ps Avr3b, which shows a typical effector gene expression pattern from a soybean root pathogen Phytophthora sojae. To modulate gene expression, we engineered Ps Avr3b promoter sequences by in situ substitution with promoter sequences from Actin(constitutive expression), Ps XEG1(early expression), and Ps NLP1(later expression) using the CRISPR/Cas9. Ps Avr3b driven by different promoters resulted in distinct expression levels across all R the tested infection time points. Importantly, those mutants with low Ps Avr3b expression successfully colonized soybean plants carrying the cognate R gene Rps3b. To dissect the difference in plant responses to the Ps Avr3b expression level, we conducted RNA-sequencing of different infection samples at 24 h postinfection and found soybean immune genes,including a few previously unknown genes that are associated with resistance. Our study highlights that fine-tuning in Avr gene expression impacts the compatibility of plant disease and provides clues to improve crop resistance in disease control management.