AtGAP1 Promotes the Resistance to Pseudomonas syringae pv. tomato DC3000 by Regulating Cell-Wall Thickness and Stomatal Aperture in Arabidopsis

Abstract

GTP is an important signaling molecule involved in the growth, development, and stress adaptability of plants. The functions are mediated via binding to GTPases which are in turn regulated by GTPase-activating proteins (GAPs). Satellite reports have suggested the positive roles of GAPs in regulating ABA signaling and pathogen resistance in plants. However, the molecular mechanisms that bring forth the pathogen resistance have remained unclear. In this study, we demonstrated that the expression of AtGAP1 was inducible by Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). The overexpression of AtGAP1 in Arabidopsis promoted the expression of PR1 and the resistance to Pst DC3000. Proteomic analyses revealed the enhanced accumulation of cell-wall-modifying proteins as a result of AtGAP1 overexpression. By microscopic analyses, we showed that the overexpression of AtGAP1 resulted in increased thickness of the mesophyll cell wall and reduced stomatal aperture, which are effective strategies for restricting the entry of foliar pathogens. Altogether, we demonstrated that AtGAP1 increases the resistance to Pst DC3000 in Arabidopsis by promoting cellular strategies that restrict the entry of pathogens into the cells. These results point to a future direction for studying the modes of action of GAPs in regulating plant cell structures and disease resistance.

Identification of stably expressed reference genes for expression studies in Arabidopsis thaliana using mass spectrometry-based label-free quantification

“…Based on the overall final ranking generated using RefFinder, ACT7 was out-performed by TIF3D1 , RPS6B , FKBP15-1 , and FBA8 in Pst DC3000 infection, by RPS6B , PSBQ2 , and FKBP15-1 in JA treatment, by all candidate reference genes except RPS6B , OVA6 , FKBP15-1 , HSP70-9 , and FBA8 in SA treatment, and by PRPL17 , PSBQ2 , and FKBP15-1 in ABA treatment ( Supplementary Table S2 ). In previous studies on A. thaliana - Pst DC3000 interaction, depending on the stress responses, the plant samples may be harvested from 1 to 5 dpi ( Mackey et al, 2003 ; Chow and Ng, 2017 ; Zhang et al, 2017 ; Cheng et al, 2022 ). Although the current study only addressed the expression stability of the candidate reference genes between 0 dpi and 3 dpi, the general expression stability of the genes upon various treatments may suggest the potential of these candidate reference genes for expression normalization at different time points after Pst DC3000 infection.…”

“…Total protein was extracted from the plant samples according to a previously described protocol ( Marx et al, 2016 ; Cheng et al, 2022 ), with minor modifications. The plant samples were ground to a fine powder in liquid nitrogen using mortar and pestle.…”

Review: Role of the plant-specific calcium-binding C2-DOMAIN ABSCISIC ACID-RELATED (CAR) protein family in environmental signaling

“…In Arabidopsis, OsGAP1 acted possibly upstream of NPR1 (Cheung et al, 2008). Arabidopsis CAR4 also promoted pathogen resistance when overexpressed in Arabidopsis (Cheng et al, 2022).…”