Folate is required for nonhost immunity of Arabidopsis against soybean pathogens.
M. BHATTACHARYYA (1), S. Kambakam (1), B. Sahu (1), R. Sumit (1), P. Singh (1), M. Ngaki (1) (1) Iowa State University, U.S.A.

The soybean stem and root rot pathogen, Phytophthora soja, can penetrate single cells of the Arabidopsis penetration deficient mutant, pen1-1. A mutant screen was undertaken in pen1-1 to identify mutants that are infected by P. sojae. Thirty putative P. sojae susceptible (pss) mutants, pss1 through pss30, showing visible necrosis following inoculation with P. sojae zoospores were identified. Fourteen of these mutants are also susceptible to the fungal pathogen Fusarium virguliforme that causes sudden death syndrome in soybean. Pss30 encodes a folate transporter (AtFOLT1). pss30 lacking AtFOLT1 showed loss of immunity to two non-adaptive soybean pathogens, P. soaje and F. virguliforme. In addition, T-DNA-insertion Arabidopsis folate biosynthetic pathway mutants are compromised in nonhost resistance against P. sojae. The loss of nonhost immunity in pss30 and folate biosynthetic mutants to P. sojae was rescued by feeding folic acid. Following P. sojae infection, folate rapidly accumulates in soybean presumably to induce effector-triggered immunity and in Arabidopsis to confer nonhost resistance. Transgenic soybean lines expressing AtFOLT1 showed enhanced resistance to F. virguliforme under growth chamber and field conditions.

Abstract Number: P17-496
Session Type: Poster