Monitoring flower bud dormancy breaking in almond through gene expression analysis

Abstract

Dormancy is a period in fruit trees lifecycle of great interest in almond (Prunus dulcis Miller D.A. Webb) breeding. Chill requirements for overcoming this stage are cultivar-specific and they are determinant for adaptation of cultivars to the climatic conditions of each zone. It is known that dormancy release for flowering is regulated by transcriptional control mechanisms as epigenetic modifications. Recently, candidate genes involved in bud dormancy and flowering date were mapped in two progenies of sweet cherry (Prunus avium). Some of these genes, EMF2, ARP4, and PIE1 co-localize with the QTL for flowering date and PIE1 are also located within the QTL for chilling requirements. These genes, together with LDL2 were mapped in the Linkage Group 4. The aim of this work was to characterize EMF2, ARP4, PIE1 and LDL2, described as epigenetic regulators, in almond cultivars with different chilling requirements and flowering time. For that purpose, gene expression was analyzed over the dormancy period of flower buds in 'Desmayo Largueta' (early flowering) and 'Penta' (extra-late flowering) cultivars. Results suggested that expression of candidate genes varied during the period of study, but that change pattern is gene-specific. Finally, comparison between expression dynamics observed in the early flowering cultivar versus the extra-late cultivar has been discussed.