Stomatal Closure and Rise in ROS/NO of Arabidopsis Guard Cells by Tobacco Microbial Elicitors: Cryptogein and Harpin

Abstract

Plants use stomatal closure mediated by elicitors as the first step of the innate immune response to restrict the microbial entry. We present a comprehensive study of the effect of cryptogein and harpin, two elicitors from microbial pathogens of tobacco, on stomatal closure and guard cell signaling components in Arabidopsis thaliana, a model plant. Cryptogein as well as harpin induced stomatal closure, while elevating the levels of reactive oxygen species (ROS) and nitric oxide (NO) in the guard cells of A. thaliana. Kinetic studies with fluorescent dyes revealed that the rise in ROS levels preceded that of NO in guard cells, when treated with these two elicitors. The restriction of NO levels in guard cells, even by ROS modulators indicates the essentiality of ROS for NO production during elicitor-triggered stomatal closure. The signaling events during elicitor-induced stomatal closure appear to converge at NADPH oxidase and ROS production. Our results provide the first report on stomatal closure associated with rise in ROS/NO of guard cells by cryptogein and harpin in A. thaliana. Our results establish that A. thaliana can be used to study stomatal responses to the typical elicitors from microbial pathogens of other plants. The suitability of Arabidopsis opens up an excellent scope for further studies on signaling events leading to stomatal closure by microbial elicitors.

Abscisic Acid-Induced Stomatal Closure: An Important Component of Plant Defense Against Abiotic and Biotic Stress

“…Several microbial elicitors (chitosan, flg22, harpin, and cryptogein) promoted stomatal closure and prevented pathogens’ entry. These elicitors produce NO and ROS via nitric oxide synthase (NOS) and NADPH oxidase, respectively ( Klüsener et al, 2002 ; Melotto et al, 2006 ; Agurla and Raghavendra, 2016 ; Gayatri et al, 2017 ; Prodhan et al, 2020 ). The combined action of ROS and NO could be imparting pathogen resistance.…”

Special issue in honour of Prof. Reto J. Strasser - Targets of nitric oxide (NO) during modulation of photosystems in pea mesophyll protoplasts: studies using chlorophyll a fluorescence

“…diligence (Feelisch 1998, Lum et al 2005. However, we are confident about the use of SNP, as in our lab, the SNP-induced stomatal closure can be reversed by specific NO scavenger 2-(4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) (Gayatri et al 2017, Agurla et al 2018.…”

The 5′‐upstream region of WRKY18 transcription factor from banana is a stress‐inducible promoter with strong expression in guard cells

“…The stress inducibility of P MusaWRKY18 can be of particular interest to drive the expression of stress-related toxic genes in transgenic plants towards improving stress tolerance. Recently, cryptogein and harpin which are strong elicitors were studied for their functions in stomatal closure as it is considered as a part of the innate immune response which prevents entry of pathogens in plants (Gayatri et al, 2017). Such elicitor peptides could be driven in plants under the control of guard cell-specific and guard cell preferred promoters including P MusaWRKY18 to further elucidate the mechanisms of elicitor induced stomatal closure and generating transgenic plants with broad spectrum resistance by SAR induction.…”

“…Research towards controlling the opening and closure of stomatal aperture through guard cell engineering is an attractive option to improve plant productivity under drought conditions (Schroeder et al, 2001). Genetic engineering of guard cells for drought resilience can involve silencing negative effectors or promoting positive regulators of ABA response (Gosti et al, 1999;Pei et al, 1998).…”