Absence of the endo‐β‐1,4‐glucanases Cel1 and Cel2 reduces susceptibility to Botrytis cinerea in tomato

Abstract

SummaryCel1 and Cel2 are members of the tomato (Solanum lycopersicum Mill) endo-b-1,4-glucanase (EGase) family that may play a role in fruit ripening and organ abscission. This work demonstrates that Cel1 protein is present in other vegetative tissues and accumulates during leaf development. We recently reported the downregulation of both the Cel1 mRNA and protein upon fungal infection, suggesting the involvement of EGases in plant-pathogen interactions. This hypothesis was confirmed by assessing the resistance to Botrytis cinerea infection of transgenic plants expressing both genes in an antisense orientation (Anti-Cel1, Anti-Cel2 and AntiCel1-Cel2). The Anti-Cel1-Cel2 plants showed enhanced resistance to this fungal necrotroph. Microscopical analysis of infected leaves revealed that tomato plants accumulated pathogen-inducible callose within the expanding lesion. Anti-Cel1-Cel2 plants presented a faster and enhanced callose accumulation against B. cinerea than wild-type plants. The inhibitor 2-deoxy-D-glucose, a callose synthesis inhibitor, showed a direct relationship between faster callose accumulation and enhanced resistance to B. cinerea. EGase activity appears to negatively modulate callose deposition. The absence of both EGase genes was associated with changes in the expression of the pathogen-related genes PR1 and LoxD. Interestingly, Anti-Cel1-Cel2 plants were more susceptible to Pseudomonas syringae, displaying severe disease symptoms and enhanced bacterial growth relative to wild-type plants. Analysis of the involvement of Cel1 and Cel2 in the susceptibility to B. cinerea in fruits was done with the ripening-impaired mutants Never ripe (Nr) and Ripening inhibitor (rin). The data reported in this work support the idea that enzymes involved in cell wall metabolism play a role in susceptibility to pathogens.

Ripening-Regulated Susceptibility of Tomato Fruit toBotrytis cinereaRequiresNORBut NotRINor Ethylene

“…Among the responses to B. cinerea shared by MG and RR fruit, expression of Cel1 (U13054), in the b-1,4-endoglucanase family, decreased 2-fold, confirming reports that the Cel1 protein is reduced when tomato leaves or fruit are inoculated with B. cinerea (Real et al, 2004;Flors et al, 2007).…”

“…Here, we show that B. cinerea infections induce the expression of LePG and LeExp1 in unripe wild-type fruit and in susceptible 42-dpa rin fruit but not in resistant nor fruit. Infection of fruit, however, also results in the decreased expression of Cel1 (GonzalezBosch et al, 1996;Flors et al, 2007), suggesting that specific aspects of ripe fruit cell wall disassembly are important for susceptibility. Changes in tomato fruit cuticle composition and structure that result from the Delayed Fruit Deterioration (DFD) mutation also contribute to changes in ripening-associated tomato fruit softening and B. cinerea susceptibility (Saladie et al, 2007).…”

“…The interaction of tomato fruit with the ascomycete Botrytis cinerea (teleomorph Botryotinia fuckeliana) is a model pathosystem for investigating necrotrophic microorganisms (Powell et al, 2000;Company and Gonzalez-Bosch, 2003;Flors et al, 2007;Cantu et al, 2008aCantu et al, , 2008b. B. cinerea is an opportunistic pathogen with a broad host range and is notoriously aggressive on fleshy fruit.…”

Estudio integral de los mecanismos de resistencia inducida. Inductores frente a estrés biótico y abiótico

“…The RT-qPCR conditions were those described by Flors et al (2007). A list of the primers used in the RT-qPCR is shown in Table 1, using GAPDH gene expression of citrus how an internal standard.…”

“…Callose deposition in response to MNSV infection was quantified from the digital photographs of the aniline blue-stained cotyledons, as described by Flors et al (2007). Observations were made with a Leica IRB epifluorescence microscope equipped with a Leica DC300F camera (Leica Microsystems, http://www.leica-microsystems.com).…”