Return of the phytoalexins - a strategy for Asian soybean rust control
S. BEYER (1), H. Schultheiss (2), J. Gätgens (3), M. Oldiges (3), C. Langenbach (1), U. Conrath (1) (1) Plant Physiology Department, RWTH-Aachen University, Germany; (2) BASF Plant Science Company GmbH, Germany; (3) Institute of Bio- and Geosciences, IBG-1: Biotechnology, Research Center Jülich, Germany

Asian soybean rust (SBR) is a devastating disease caused by the fungus Phakopsora pachyrhizi. Soybean varieties with resistance to all P. pachyrhizi isolates are currently unavailable. Thus, fungicides are the current means to control SBR. Because P. pachyrhizi races become insensitive to fungicides, soybean varieties with durable SBR resistance are urgently needed. In an attempt to exploit nonhost resistance (NHR)-associated Arabidopsis thaliana genes for genetically engineered soybean resistance to SBR, we identified POSTINVASION-INDUCED NONHOST RESISTANCE GENE (PING)11 whose expression is specifically activated during Arabidopsis postinvasion SBR resistance. PING11 encodes a key enzyme in plant secondary metabolism. Consistently, a phytoalexin exclusively accumulated in P. pachyrhizi-inoculated pen2 mutants with postinvasion NHR to SBR. In vitro and in situ analyses revealed that the phytoalexin inhibited P. pachyrhizi uredospore germination, counteracted fungal penetration, and reduced rust symptom development. Overexpression of PING11 in Arabidopsis, Nicotiana benthamiana and Glycine max lead to constitutive accumulation of the phytoalexin and increased SBR resistance in the soybean host. Current work addresses the phytoalexin’s mode of action and its potential for providing resistance to other fungal diseases.

Abstract Number: P20-719
Session Type: Poster