Chilling injury mechanism of hardy kiwifruit (Actinidia arguta) was revealed by proteome of label-free techniques.

Abstract

Refrigeration is an important method to extend shelf life of hardy kiwifruit. However, the inappropriate storage temperature can lead to chilling injury in the fruit. We found that firmness, total soluble solids, and total polyphenolic content of the fruit exposed to 0℃ environment were apparently lower, and titratable acidity content, browning rate, weight loss rate, electrolyte leakage, proline content, and malondialdehyde content were higher obviously than 4℃. A total of 244 differentially expressed proteins were found result from differential temperatures, among which 113 were up-regulated and 131 were down-regulated. Subcellular localization results presented that the differentially expressed proteins which were affected by low temperature were located in cytoplasmic, chloroplast, nuclear, mitochondrial, plasma membrane, and extracellular. Kyoto Encyclopedia of Genes and Genomes analysis showed that the differentially expressed proteins were mainly participated in synthesis of citrate cycle, oxidative phosphorylation, fatty acid biosynthesis, and starch and sucrose metabolism. Protein-protein interaction results revealed that central proteins interaction points respectively are 30S ribosomal proteins, 30S ribosomal protein S7, chloroplastic, cell division cycle 5-like protein, 50S ribosomal protein, ribosomal protein, ribosomal protein L6 protein, and SRP54 subunit protein. The quality deviations of all identified peptides were mainly distributed within 10ppm, and MS2 has an ideal andromeda score, with more than 87.82% peptide scores above 60 points, and the median peptide score of 99.28 points. Therefore, the results of this study provide important information for new gene revelation and gene interaction relationship in hardy kiwifruit of chilling injury. PRACTICAL APPLICATIONS: Inhibition of cold damage in hardy kiwifruit under low temperature is very important work for the development of its storage industry. However, many qualities of fruit will deteriorate after long-term cold storage and those biological activities of the fruits are regulated by proteins. It is, therefore, of great significance to reveal the key proteins caused cold damage in hardy kiwifruit. Moreover, the study results could provide a scientific information for the quality improvement and genetic modification of hardy kiwifruit.