Alterations in Primary Carbon Metabolism in Cucumber Infected with Pseudomonas syringae pv lachrymans: Local and Systemic Responses

Abstract

The reconfiguration of the primary metabolism is essential in plant–pathogen interactions. We compared the local metabolic responses of cucumber leaves inoculated with Pseudomonas syringae pv lachrymans (Psl) with those in non-inoculated systemic leaves, by examining the changes in the nicotinamide adenine dinucleotides pools, the concentration of soluble carbohydrates and activities/gene expression of carbohydrate metabolism-related enzymes, the expression of photosynthesis-related genes, and the tricarboxylic acid cycle-linked metabolite contents and enzyme activities. In the infected leaves, Psl induced a metabolic signature with an altered [NAD(P)H]/[NAD(P)+] ratio; decreased glucose and sucrose contents, along with a changed invertase gene expression; and increased glucose turnover and accumulation of raffinose, trehalose, and myo-inositol. The accumulation of oxaloacetic and malic acids, enhanced activities, and gene expression of fumarase and l-malate dehydrogenase, as well as the increased respiration rate in the infected leaves, indicated that Psl induced the tricarboxylic acid cycle. The changes in gene expression of ribulose-l,5-bis-phosphate carboxylase/oxygenase large unit, phosphoenolpyruvate carboxylase and chloroplast glyceraldehyde-3-phosphate dehydrogenase were compatible with a net photosynthesis decline described earlier. Psl triggered metabolic changes common to the infected and non-infected leaves, the dynamics of which differed quantitatively (e.g., malic acid content and metabolism, glucose-6-phosphate accumulation, and glucose-6-phosphate dehydrogenase activity) and those specifically related to the local or systemic response (e.g., changes in the sugar content and turnover). Therefore, metabolic changes in the systemic leaves may be part of the global effects of local infection on the whole-plant metabolism and also represent a specific acclimation response contributing to balancing growth and defense.

Comprehensive elucidation of the differential physiological kale response to cytokinins under in vitro conditions

“…The content of nicotinamide adenine dinucleotides was determined using enzyme cycling assays, employing 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) as the terminal electron acceptor, with phenazine methosulfate (PMS) serving as an electron carrier. The reaction was based on either the conversion of EtOH to acetaldehyde, catalyzed by alcohol dehydrogenase (ADH, EC 1.1.1.1) for NAD(H) determination, or the conversion of glucose-6-phosphate (G6P) to 6-phosphogluconolactone by glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) for NADP(H) determination [ 22 , 23 ].…”

Antifungal Properties of Bio-AgNPs against D. pinodes and F. avenaceum Infection of Pea (Pisum sativum L.) Seedlings

“…Sugars and their metabolism contribute to a plant's immunity as they are associated with increasing cell wall lignification, oxidative burst, the stimulation of flavonoid synthesis (sucrose), and some PR protein expression (by glucose) [71,100]. It has also been suggested that a lowered hexose/sucrose ratio during infection can trigger PR gene expression [102]. Infection forces plants to undergo carbon nutrient mobilization, accompanied by photosynthesis reduction, increased respiration, and alterations in nitrogen and lipid metabolism.…”

Phenolic Acids and Amaryllidaceae Alkaloids Profiles in Leucojum aestivum L. In Vitro Plants Grown under Different Light Conditions

“…Soluble carbohydrates are synthesised, for example, in response to osmotic stress, protecting cellular members and improving survival under stress conditions [ 29 ]. Biotic elicitors, such as pathogen infection, also produce changes in the distribution and metabolism of carbohydrates in plants [ 30 ]. Red plus blue LEDs [ 31 ] stimulate carbohydrate biosynthesis in vitro in Doritaenopsis plants, as does white LED light in N .…”