Proteome analysis of two Vitis vinifera cvs. reveals different responses to hot-water treatment and cold storage and a diverse endophyte population

Hot water treatment (HWT; 50°C for 30 min), is currently the most practical and consistently effective control for trunk disease pathogens in grapevine cuttings. However, HWT canreduce strike rate. The effects of HWT on cutting physiology were investigated using two-dimensional gel electrophoresis and tandem mass spectrometry. Expression of stress related proteins was studied in dormant Vitis vinifera cv. Pinot Noir [PN] and CabernetSauvignon [CS] cuttings 1 and 24 h after HWT, and after 13 weeks cold storage (2°C) in sealed (hypoxic) or unsealed storage bags. Although there was a subset of proteins commonto both varieties, the base proteome of CS was much larger than that of PN. At 1 h post-HWT, protein expression was suppressed in CS, but increased in PN. Hypoxic cold storage suppressed protein expression in PN, but increased expression in CS. Relatively high levels of pathogenesis related PR10 in dormant tissue compared to non-dormant tissue may explain the absence of visible symptoms in dormant cuttings infected with trunk disease pathogens. Proteins from microorganisms including bacteria, yeasts and fungi were alsofound in both varieties suggesting a diverse population ofendophytes. Some of these apparent endophytes are benign, but proteins attributed to known pathogens of plants and mammals were also present. A post HWT recovery period of 24 h is recommendedbefore further processing of cuttings, particularly for CS. The different responses to hypoxic cold storage suggest that manipulating cold storage conditions for different varieties might be a useful means of prolonging storage life.