Ascorbic Acid Deficiency in Arabidopsis Induces Constitutive Priming That is Dependent on Hydrogen Peroxide, Salicylic Acid, and the NPR1 Gene

Abstract

The ascorbic acid (AA)-deficient Arabidopsis thaliana vtc1-1 mutant exhibits increased resistance to the virulent bacterial pathogen Pseudomonas syringae. This response correlates with heightened levels of salicylic acid (SA), which induces antimicrobial pathogenesis-related (PR) proteins. To determine if SA-mediated, enhanced disease resistance is a general phenomenon of AA deficiency, to elucidate the signal that stimulates SA synthesis, and to identify the biosynthetic pathway through which SA accumulates, we studied the four AA-deficient vtc1-1, vtc2-1, vtc3-1, and vtc4-1 mutants. We also studied double mutants defective in the AA-biosynthetic gene VTC1 and the SA signaling pathway genes PAD4, EDS5, and NPR1, respectively. All vtc mutants were more resistant to P. syringae than the wild type. With the exception of vtc4-1, this correlated with constitutively upregulated H(2)O(2), SA, and messenger RNA levels of PR genes. Double mutants exhibited decreased SA levels and enhanced susceptibility to P. syringae compared with the wild type, suggesting that vtc1-1 requires functional PAD4, EDS5, and NPR1 for SA biosynthesis and pathogen resistance. We suggest that AA deficiency causes constitutive priming through a buildup of H(2)O(2) that stimulates SA accumulation, conferring enhanced disease resistance in vtc1-1, vtc2-1, and vtc3-1, whereas vtc4-1 might be sensitized to H(2)O(2) and SA production after infection.

Expression of a GDP-L-galactose phosphorylase-like gene in a Chinese wild Vitis species induces responses to Erysiphe necator and defense signaling molecules

“…Previous research has shown that fruit was able to mount a rapid and efficient defense response and to maintain a generally higher L-AsA content after being infected by B. cinerea (Davey et al, 2007), which is in accordance with results of the present study. In contrast, the AsA-deficient A. thaliana VTC1, VTC2, VTC3, and VTC4 mutants were more resistant to P. syringae relative to the wild-type (Pavet et al, 2005;Mukherjee et al, 2010).…”

Arabidopsis NATA1 acetylates putrescine and decreases defense-related hydrogen peroxide accumulation

“…As H 2 O 2 acts synergistically with salicylic acid to induce plant defense responses (Neuenschwander et al, 1995;Sharma et al, 1996;Alvarez et al, 1998;Mukherjee et al, 2010), we measured salicylic acid concentrations in response to DC3000 infection. Although P. syringae infiltration into Arabidopsis leaves significantly increased the concentration of salicylic acid 2 d later, there was no significant difference in the free or total salicylic acid content of wild-type and nata1 leaves ( Fig.…”

“…Salicylic acid and H 2 O 2 act synergistically to initiate both local and systemic plant responses to pathogen infection (Neuenschwander et al, 1995;Sharma et al, 1996;Alvarez et al, 1998;Mukherjee et al, 2010). A rapid increase in H 2 O 2 production, initiated through the activity of NADPH oxidase, occurs as a hypersensitive response to pathogen infection in many plant species (Lamb and Dixon, 1997;Torres et al, 2005).…”

Mutant Allele-Specific Uncoupling of PENETRATION3 Functions Reveals Engagement of the ATP-Binding Cassette Transporter in Distinct Tryptophan Metabolic Pathways

“…The regulation of this loop is linked to the glutathioneascorbate cycle. For instance, the ascorbate-deficient vitamin C mutants hyperaccumulate constitutively both SA and hydrogen peroxide (Mukherjee et al, 2010). In addition, a study using Arabidopsis mutants catalasedeficient2 and glutathione-deficient cadmium-sensitive2 indicates that the cellular glutathione redox status is a key player linking intracellular hydrogen peroxide with the activation of the SA pathway (Han et al, 2013).…”