Proteomic analysis of ripening tomato fruit infected by Botrytis cinerea

Abstract

Botrytis cinerea, a model necrotrophic fungal pathogen that causes gray mold as it infects different organs on more than 200 plant species, is a significant contributor to postharvest rot in fresh fruit and vegetables, including tomatoes. By describing host and pathogen proteomes simultaneously in infected tissues, the plant proteins that provide resistance and allow susceptibility and the pathogen proteins that promote colonization and facilitate quiescence can be identified. This study characterizes fruit and fungal proteins solubilized in the B. cinerea-tomato interaction using shotgun proteomics. Mature green, red ripe wild type and ripening inhibited (rin) mutant tomato fruit were infected with B. cinerea B05.10, and the fruit and fungal proteomes were identified concurrently 3 days postinfection. One hundred eighty-six tomato proteins were identified in common among red ripe and red ripe-equivalent ripening inhibited (rin) mutant tomato fruit infected by B. cinerea. However, the limited infections by B. cinerea of mature green wild type fruit resulted in 25 and 33% fewer defense-related tomato proteins than in red and rin fruit, respectively. In contrast, the ripening stage of genotype of the fruit infected did not affect the secreted proteomes of B. cinerea. The composition of the collected proteins populations and the putative functions of the identified proteins argue for their role in plant-pathogen interactions.

Figure 1

Schematic depiction of protein extraction and peptide preparation for proteomic analysis for RR, rin and MG tomato fruit infected with B. cinerea

Figure 2

Tomato fruit infected by Botrytis cinerea at the MG (31 dpa), RR (42 dpa) stages of wild type AC and at 42 dpa of the rin non-ripening mutant.

Figure 3

Area-proportional Venn diagrams showing overlap of tomato proteins (a) and Botrytis cinerea proteins (b) identified from RR, MG and rin tomatoes infected with Botrytis cinerea.

Figure 4

Hypothetical model representing the proteins secreted during a plant-fungal interaction. Pathogenic fungi facilitate their colonization of plant tissue by producing Cell Wall Degrading Enzymes (CWDEs) that fragment plant cell wall polysaccharides. The oligosaccharides that are generated by these glycanases provide the fungus with a carbon source but are also perceived by and elicit defense responses in the host plant. As part of that response, plants produce proteins that inhibit fungal glycanases and thereby increase the life time of the biologically active oligosaccharides. The fragmentation of the fungal cell wall by plant defense related proteins also generates oligosaccharides that induce plant defense responses. The fungus itself may in turn produce defensive proteins to prevent the degradation of its own cell wall and limit its perception by the plant. Thus, the interplay between fungal and plant glycanases and their respective inhibitors may in large part determine the outcome of attempted pathogenesis. The height of the colored arrows indicates the relative abundance of that particular protein group identified when MG (green arrows), RR (red arrows) and rin (blue arrows) tomatoes are infected with B. cinerea.