Elucidating the mechanisms of chilling injury resistance in peach through proteome analysis

FERREYRA, LAURA; GABILONDO, JULIETA; BUDDE CLAUDIO; DRINCOVICH, MA. FABIANA; MÜLLER, GABRIELA L.; BUSTAMANTE, CLAUDIA A.

Congreso; Reunión anual Edición LVIII; 2022

Peach is a perishable fruit that deteriorates quickly once harvested at room temperature. Storage at 0°C is used to prevent fruit decay and extend shelf life. However, this practice produces physiological disorders called “chilling injury” (CI), leading to loss in quality. The aim of this study was to analyze and compare the proteome of a cultivar resistant to CI (Elegant Lady) subjected to different post-harvest conditions: in harvested fruits (H), the stage where it reached physiological maturity; in fruits kept in a chamber at 20◦C for 5 days (organoleptic characteristics suitable for consumption), called RS (room temperature-storage); in fruits stored at 0◦C for 21 days (CS21, cold storage for 21 days); and in fruits stored at 0◦C for 21 days followed by 5 days at 20◦C (CS21+RS). Proteins were extracted from mesocarp tissue and run on polyacrylamide gels before sending them to Proteomics Core Facility CEQUIBIEM for Mass Spectrometry analysis. Proteins containing a fold-change ≥2 and p ≤0.05 were considered for the analysis. In the comparison H vs RS, several proteins involved in cell wall degradation such as pectinesterase and endo-polygalacturonase were increased, according to the loss of firmness observed. Also, a laccasse was detected, which plays a role in the biosynthesis of lignin, and a xyloglucan endotransglucosylase, involved in cell wall biogenesis, was found decreased. In addition, an increase in the enzymes involved in the ascorbate-glutathione cycle, ascorbate peroxidase and glutathione reductase, was detected, which could be involved in maintaining the redox balance during ripening and senescence. In the comparison H vs CS21, an increase of the expression of a chitinase, a pathogenesis-related protein, and two thaumatin proteins were observed, which could have a role in the protection of cell wall structure against chilling injury and pathogen attack. Finally, in the comparison RS vs CS21+RS, various enzymes implicated in the carbohydrate metabolism, such as phosphoglycerate mutase, glucose-6-phosphate isomerase and citrate synthase, decreased their levels, suggesting a decline in glycolysis and Krebs pathways in the ripening after a prolonged cold treatment. Also, it was observed an increase and decrease of proteins involved in the metabolism of proteins that could suggest an active turnover in these samples. Overall, our results show that in H vs RS, the reconfiguration of the proteome was as expected for a ripening process accumulating predominantly wall degradation enzymes. While in the comparison RS vs CS21+RS, an inhibition of pathways that degrade carbohydrates was observed. Our previous results in this variety showed a large increase in sucrose, glucose, fructose and raffinose in the comparison H vs CS21. These sugars that act as osmoprotectants plus thaumatins that protect the cell wall, producing a decrease in wooliness symptom (lack of juice), might be the most probable cause of resistance to CI in EL.