Gene expression analysis of related dormancy genes during bud dormancy progression in field conditions in almond

Abstract

Flowering time is a trait of great interest in almond breeding. Knowing the molecular basis underlying this trait would allow the development of efficient selection tools for almond breeding. Almond flowering comes in response to a pattern of low temperatures (for bud dormancy breaking) and high temperatures (after bud dormancy breaking). These chill and heat requirements ensure that flowering will take place under suitable conditions for pollination in each growing zone. In order to identify the genome regions involved in flowering time and dormancy regulation, four genes including genes related to transcription regulation and phytohormone signaling were analyzed by qPCR. These assays were performed in flower buds of two almond cultivars including 'Desmayo Largueta' (extra-early flowering) and 'Penta' (extra-late flowering), during bud dormancy progression. Results suggested that the expression of PdDREB2c, PdAFP and PdGA2ox was notably reduced at the moment of bud dormancy breaking, highlighting the role of these genes in maintaining bud dormancy and thus determine the flowering time. However, expression of PdPIE1 largely increased close to the moment of bud dormancy breaking, which could indicate the involvement of an epigenetic regulator to control this process.