Reduced susceptibility of tomato stem to the necrotrophic fungusBotrytis cinereais associated with a specific adjustment of fructose content in the host sugar pool

Abstract

Background and aims Plant soluble sugars, as main components of primary metabolism, are thought to be implicated in defence against pathogenic fungi. However, the function of sucrose and hexoses remains unclear. This study aimed to identify robust patterns in the dynamics of soluble sugars in sink tissues of tomato plants during the course of infection by the necrotrophic fungus Botrytis cinerea. Distinct roles for glucose and fructose in defence against B. cinerea were hypothesized. Methods We examined sugar contents and defence hormonal markers in tomato stem tissues before and after infection by B. cinerea, in a range of abiotic environments created by various nitrogen and water supplies. Key Results Limited nitrogen or water supplies increased tomato stem susceptibility to B. cinerea. Glucose and fructose contents of tissues surrounding infection sites evolved differently after inoculation. The fructose content never decreased after inoculation with B. cinerea, while that of glucose showed either positive or negative variation, depending on the abiotic environment. An increase in the relative fructose content (defined as the proportion of fructose in the soluble sugar pool) was observed in the absence of glucose accumulation and was associated with lower susceptibility. A lower expression of the salicylic acid marker PR1a, and a lower repression of a jasmonate marker COI1 were associated with reduced susceptibility. Accordingly, COI1 expression was positively correlated with the relative fructose contents 7 d after infection. Conclusions Small variations of fructose content among the sugar pool are unlikely to affect intrinsic pathogen growth. Our results highlight distinct use of host glucose and fructose after infection by B. cinerea and suggest strongly that adjustment of the relative fructose content is required for enhanced plant defence.

Resistance against Ralstonia solanacearum in tomato depends on the methionine cycle and the γ‐aminobutyric acid metabolic pathway

“…In the process of pathogen infection a series of genes and pathways are activated, and extensive efforts have been devoted to understanding plant defense signaling pathways (Uppalapati et al ., ). Emerging evidence has shown a causal link between primary metabolism and defense responses to plant pathogens (Bolton, ; Rojas et al ., ; Lecompte et al ., ; Schwachtje et al ., ). In the present study, MTC was demonstrated to be extensively involved in R. solanacearum –tomato interactions.…”

Metabolomics to Exploit the Primed Immune System of Tomato Fruit

“…Using top-down modelling based on the construction of generalised linear models [30], we demonstrate that metabolomics data can be used to accurately predict the measured resistance to various fruit pathogens ( Figure 6A). Besides, through the evaluation of the occurrence of best predictors, our data indicate that soluble sugars, more specifically fructose [42], and defence metabolites are pivotal to predict the resistance to fruit pathogens (Table S1). Clearly, a more global systems biology approach based on a higher level of variation in the conditions (e.g., multiple genotypes or priming treatments, various growth stages of the fruit, several infection points) will shed some light on the underlying mechanisms of fruit-pathogen interactions.…”

Potassium deficiency aggravates yield loss in rice by restricting the translocation of non‐structural carbohydrates under Sarocladium oryzae infection condition

“…Pathogen infection also changes the accumulation traits of carbon assimilates (Lecompte et al ). Soluble sugar, starch and NSC were sharply accumulated in diseased FL, moreover, K deficiency significantly aggravates the accumulation of soluble sugar in FL, which is consistent with the high contribution of K deficiency to the content of soluble sugar and starch in FL (Fig.…”

“…Meanwhile, K deficiency also induces accumulation of low‐molecular‐weight compounds in host plants, such as soluble sugars and free amino acids, among others (Hu et al , Hu et al ). These primary metabolites of carbon are readily accessible to pathogens (Marschner , Lecompte et al ) and are easily hijacked by pathogens. By contrast, a sufficient K supply alleviated the membrane lipid peroxidation and increases the exportation of soluble sugar from source leaves (Oosterhuis et al ) and increases the internal competition of a host plant for nutrient resources (Wang et al ).…”