Abstract

Peach (Prunus persica L. Batsch) is a climacteric export fruit with high economic and commercial value for Chile. During peach development, there are physiological changes induced by a strict phytohormonal control that can alter the final quality of the fruit. Physiological evidence in fruit trees suggests that exogenous application of phytohormone cytokinin could delay the maturation process in the fruit. However, the molecular mechanisms involved in cytokinin effect on peach are barely known. To address this question, we exogenously applied cytokinin to peach fruit in both field (TDZ) and laboratory (trans-zeatin) settings at maturation stage. By using bi-directional blast analysis, we identified putative orthologs of ripening-related genes and conserved cytokinin-induced genes that were potentially regulated by cytokinin in peaches. Through bioinformatic and gene expression analyses, we have identified 23 genes that express differentially under cytokinin treatment, 21 of which exhibited cytokinin responsive cis- elements in their regulatory region. These include genes related to ethylene biosynthesis such as ACCO, EREBP, and CPK28. Additionally, some of these cytokinin responsive genes map to a region on the TxE map that contains a previously identified QTL related to fruit ripening, suggesting that these candidate genes may be related to the ripening process. In conclusion, exogenous application of cytokinin on peach fruits under laboratory and field work has enabled us to identify a set of novel cytokinin-responsive genes in peach fruit related to the maturity/ripening process. CONICYT Fondecyt/Regular N°1171016 CONICYT-PCHA/Doctorado Nacional/2014-21140426