Open AccessInduced systemic resistance responses in perennial ryegrass against M agnaporthe oryzae elicited by semi‐purified surfactin lipopeptides and live cells of B acillus amyloliquefaciens
Author(s) -
Rahman Alamgir,
Uddin Wakar,
Wenner Nancy G.
Publication year - 2015
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/mpp.12209
Subject(s) - surfactin , microbiology and biotechnology , biology , phenylalanine ammonia lyase , apoplast , peroxidase , lipopeptide , cell wall , biochemistry , bacteria , enzyme , genetics , bacillus subtilis
Summary The suppressive ability of several strains of cyclic lipopeptide‐producing B acillus rhizobacteria to grey leaf spot disease caused by M agnaporthe oryzae has been documented previously; however, the underlying mechanism(s) involved in the induced systemic resistance (ISR) activity in perennial ryegrass ( L olium perenne L .) remains unknown. Root‐drench application of solid‐phase extraction ( SPE )‐enriched surfactin and live cells of mutant B acillus amyloliquefaciens strain FZB42‐AK3 (produces surfactin, but not bacillomycin D and fengycin) significantly reduced disease incidence and severity on perennial ryegrass. The application of the treatments revealed a pronounced multilayered ISR defence response activation via timely and enhanced accumulation of hydrogen peroxide ( H 2 O 2 ), elevated cell wall/apoplastic peroxidase activity, and deposition of callose and phenolic/polyphenolic compounds underneath the fungal appressoria in naïve leaves, which was significantly more intense in treated plants than in mock‐treated controls. Moreover, a hypersensitive response ( HR )‐type reaction and enhanced expression of LpPrx (Prx, peroxidase), LpOXO4 (OXO, oxalate oxidase), LpPAL (PAL, phenylalanine ammonia lyase), LpLOXa (LOX, lipoxygenase), LpTHb (putative defensin) and LpDEFa (DEFa, putative defensin) in perennial ryegrass were associated with SPE‐enriched surfactin and live AK3 cell treatments, acting as a second layer of defence when pre‐invasive defence responses failed. The results indicate that ISR activity following surfactin perception may sensitize H 2 O 2 ‐mediated defence responses, thereby providing perennial ryegrass with enhanced protection against M . oryzae .