Early Cold-Induced Peroxidases and Aquaporins Are Associated With High Cold Tolerance in Dajiao (Musa spp. ‘Dajiao’)

Banana is an important tropical fruit with high economic value. One of the main species (cultivar Cavendish) is susceptible to low temperature, while another close relative specie (Dajiao), has considerably higher cold tolerance. We have reported that some membrane proteins appear involved in cold tolerance of Dajiao via antioxidation mechanism. To investigate early cold stress response of Dajiao, here we applied comparative membrane proteomics analysis for both cold-sensitive Cavendish and cold-tolerant Dajiao subjected to cold stress at 10 °C for 0, 3 and 6 h. There are 2,333 and 1,834 proteins being identified in Cavendish and Dajiao respectively. Subsequent bioinformatics analyses show that 692 Cavendish proteins and 524 Dajiao proteins are predicted to be membrane proteins, in which 82 and 137 differentially expressed membrane proteins (DEMPs) were found in Cavendish and Dajiao, respectively. Interestingly, the number of DEMPs with increased abundance at 3 h cold treatment in Dajiao (80) is seven times more than that in Cavendish (11). GO molecular function analysis of DEMPs for Cavendish and Dajiao indicates that they both belong to eight categories including hydrolase activity, binding, transporter activity, antioxidant activity, etc., but the number in Dajiao is twice that in Cavendish. Strikingly, we found peroxidases and aquaporins among the protein groups, whose abundance is significantly increased at 3 h cold treatment in Dajiao. Some of the peroxidases and aquaporins were crossly verified by reverse transcription-PCR (RT-PCR), multiple reaction monitoring (MRM) and green fluorescent protein-based (GFP-based) subcellular localization analysis, demonstrating the global membrane proteomics data are reliable. In combining with the physiologic and biochemical data, we found the membrane-bound Peroxidase 52 and P7, and aquaporins (MaPIP1;1, MaPIP1;2, MaPIP2;4, MaPIP2;6, MaTIP1;3) mainly involved in decreased lipid peroxidation, and maintaining leaf cell water potential, which appear to be the key cellular adaptation contributing to the cold tolerance of Dajiao. This membrane proteomics study provides new insights into the cold stress tolerance mechanism in banana, toward potential applications for ultimate genetic improvement of cold tolerances in banana. Key words: Musa spp. Cavendish; Musa spp. Dajiao; Quantitative proteomics; Cold tolerance; Peroxidase; Aquaporin.