Poster: Plant Pathogen/Symbiont Interactions

Abs # 729: Bacterial Volatiles Elicit Growth Promotion and Induced Resistance in Arabidopsis

Presenter:	Farag, Mohamed A, mfarag73@yahoo.com
Authors	Farag, Mohamed A (A)   Ryu, Choong-Min  (B)   Hu, Chia-Hui  (C)   Reddy, M S (C)   Pare, Paul W (A)   Kloepper, Joseph W (C)
Affiliations:	(A): Texas Tech University, Chem & Biochem Dept (B): Plant Biology Division, Noble Foundation (C): Auburn University, Entomology & Plant Path Dept

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil bacteria that colonize roots, enhance plant growth, and activate plant defences against microbial pathogens. Here we present data that some PGPR strains release a blend of volatile organic compounds (VOCs) that promote growth in Arabidopsis seedlings and induce resistance against Erwinia carotovora subsp. carotovora. In particular, the volatile components 2,3-butanediol and acetoin were released exclusively from two PGPR strains that trigger the greatest level of growth promotion and induced disease resistance. Furthermore, pharmacological applications of 2,3-butanediol induced growth promotion and induced resistance, while bacterial mutants blocked in 2,3-butanediol and acetoin synthesis were devoid in growth-promotion and induced resistance capacities. Using transgenic and mutant lines of Arabidopsis, we provide evidence that the signal pathway activated by volatiles from one PGPR strain is dependent on cytokinin activation for growth promotion and dependent on an ethylene-signaling pathway for induced pathogen resistance. This discovery provides new insight into the role of bacteria VOCs as initiators of plant growth promotion and defense responses in plants.