Barley mildew and its elicitor chitosan promote closed stomata by stimulating guard‐cell S‐type anion channels

Abstract

SUMMARYStomatal closure is known to be associated with early defence responses of plant cells triggered by microbeassociated molecular patterns (MAMPs). However, the molecular mechanisms underlying these guard-cell responses have not yet been elucidated. We therefore studied pathogen-induced changes in ion channel activity in Hordeum vulgare guard cells. Barley mildew (Blumeria graminis) hyphae growing on leaves inhibited light-induced stomatal opening, starting at 9 h after inoculation, when appressoria had developed. Alternatively, stomatal closure was induced by nano-infusion of chitosan via open stomata into the substomatal cavity. Experiments using intracellular double-barreled micro-electrodes revealed that mildew stimulated S-type (slow) anion channels in guard cells. These channels enable the efflux of anions from guard cells and also promote K + extrusion by altering the plasma membrane potential. Stimulation of S-type anion channels was also provoked by nano-infusion of chitosan. These data suggest that MAMPs of mildew hyphae penetrating the cuticle provoke activation of S-type anion channels in guard cells. In response, guard cells extrude K + salts, resulting in stomatal closure. Plasma membrane anion channels probably represent general targets of MAMP signaling in plants, as these elicitors depolarize the plasma membrane of various cell types.

Calcium-Dependent Protein Kinase CPK6 Positively Functions in Induction by Yeast Elicitor of Stomatal Closure and Inhibition by Yeast Elicitor of Light-Induced Stomatal Opening in Arabidopsis

“…3; Supplemental Fig. S1) 1989; Pei et al, 1997;Munemasa et al, 2007;Koers et al, 2011;Xue et al, 2011;Hua et al, 2012). YEL was reported to activate anion channel in root cells (Wu et al, 2011).…”

“…Elicitors derived from microbial surface mimic pathogen attack and induce stomatal closure in various plant species such as Solanum lycopersicum (Lee et al, 1999), Commelina communis (Lee et al, 1999), Hordeum vulgare (Koers et al, 2011), and Arabidopsis (Arabidopsis thaliana; Melotto et al, 2006;Khokon et al, 2010). Yeast elicitor (YEL) induces stomatal closure in Arabidopsis (Klüsener et al, 2002;Khokon et al, 2010;Salam et al, 2013).…”

MAP Kinases, MPK9 and MPK12, Regulate Chitosan-Induced Stomatal Closure

“…[1][2][3][4][5] CHT-induced stomatal closure such as ABA-and MeJA-induced stomatal closure is accompanied by ROS production and [Ca 2þ ] cyt oscillation in guard cells. [1][2][3] In Pisum sativum, CHT-induced ROS production is mediated by NADPH oxidases, 3) whereas CHTinduced ROS production is mediated by SHAM-sensitive peroxidases in Arabidopsis thaliana.…”

The regulatory mechanism of fungal elicitor-induced secondary metabolite biosynthesis in medical plants

“…Chitosan also induces the accumulation of phytoalexins in tissues of host plants, decreasesthe total content and changes the composition of free sterols producing adverse effects on infesters, activated chitinases, beta-glucanases, and lipoxygenases, and stimulates the generation of reactive oxygen species (Vasyukova et al 2001). Barley mildew and its elicitor chitosan promotes closed stomata by stimulating guard-cell S-type anion channels (Koers et al 2011). It has also been reported that the addition of chitosan, chitosan oligosaccharide and alginate oligosaccharide to the culture of P. ginseng hairy roots caused inhibition of growth but total ginseng saponin accumulated slightly with an increase in elicitor concentration .…”