Abstract: Soybean root rot disease caused by Phytophthora sojae (P. sojae) results in considerable losses in soybean yield, which is difficult to control by chemicals. P. sojae secretes large numbers of effectors to target host factors for favoring infection. Genetic engineering of these host targets is a promising strategy to boost soybean resistance. Although the CRISPR/Cas9-mediated gene editing of susceptibility genes has been used in crop disease resistant breeding, there are no reports about editing soybean susceptibility genes to enhance soybean resistance to soybean root rot disease. We previously found that a key P. sojae effector PsAvh52 suppresses soybean immunity by targeting GmTAP1, which enhances the susceptibility of soybean to P. sojae. Here we focused on knocking out the GmTAP1 by CRISPR/Cas9 gene editing system in soybean. Loss-of-function of GmTAP1 exhibited an enhanced resistance to three P. sojae strains P231, P233, and P234. We also examined the reactive oxygen species (ROS) production, the expression of (PTI)-responsive genes and MAPK activity and found that loss-of-function of GmTAP1 had less effects on plant basal immunity. Moreover, there was no significant difference in plant height, pod number per plant, hundred-grain weight, and yield per plant by investigating the agronomic traits of tap1 mutants in the field. In summary, we created new soybean lines resistant to several P. sojae strains and these lines had no agronomic penalties in the field.

Key words: CRISPR/Cas9, Genome editing, GmTAP1, Phytophthora sojae, soybean