Influence of pre-harvest calcium, potassium and triazole application on the proteome of apple at harvest

Braeburn browning disorder is a storage disease characterised by flesh browning and lens-shaped cavities. The incidence of this postharvest diorder is known to be affected by pre-harvest application of fertilisers and triazole-based fungicides. Recent work has shown that calcium and potassium reduced the incidence of Braeburn browning disorder, while triazoles had the opposite effect. This study addresses the hypothesis of an early proteomic imprint in the apple fruit at harve induced by the pre-harvest factors applied. If so, this could be used for an early screening of apple fruit at harvest for their postharvest susceptibility to flesh browning. Results: Calcium and triazole had significant effects, while potassium did not. One hundred and thirty proetin families were identified, of which 29 were significantly altered after calcium and 63 after triazole treatment. Up-regulations of important antioxicant enzymes was correlated with calcium fertilisation, while triazole induced alterations in the levels of respiration and ethylene biosynthesis related proteins. Conclusions: Pre-harvest fertiliser and fungicide application had considerable effects on the apple proteome at harvest. Thes changes, together with the applied storage conditions will determine whether or net BBD develops.