Response of Dormancy-associated MADS-box (DAM) and Flowering Locus T (FT) genes to contrasting temperature conditions during dormancy in apricot (Prunus armeniaca L.).

Abstract

Chilling requirement (CR) fulfilment is critical for successful flowering in temperate fruit trees. In mild-winter regions, several anomalies can occur when the cultivar-specific CR is not fully met, including irregular budbreak, bud abortion, and ultimately reduced fruit set. In this study, we examined the molecular regulation of dormancy release in three apricot (Prunus armeniaca L.) cultivars grown under contrasting climates (warm vs. cold/mild winters). We focused on Dormancy-associated MADS-box (DAM) genes and Flowering Locus T (FT) gene using RT-qPCR to evaluate their potential as molecular markers for endodormancy release and indicators of cultivar adaptability. Under moderate differences in chill accumulation between sites, gene expression patterns generally exhibited genotype-specific responses to chilling. Expression of DAM4-6 correlated with prolonged cold exposure and was progressively downregulated towards dormancy release. Faster DAM downregulation in warmer sites corresponded to shallower dormancy and earlier release, consistent with the forcing-shoot experiment results. Among these genes, DAM4 required greater chill exposure for downregulation and emerged as a potential physiological indicator of the transition from endodormancy to ecodormancy, downregulating once approximately 75% of cultivar-specific CR had been fulfilled. However, DAM expression showed limited variation among areas during the later stages, even though substantial differences were observed in the number of viable buds and fruit set in the high-chill cultivar. By contrast, FT expression appeared more sensitive to insufficient chilling in this cultivar. These findings suggest that DAM genes are reliable markers of endodormancy progression, whereas FT may serve as an indicator of flowering quality under suboptimal chill accumulation. Integrating molecular, phenological and climatic data could enhance predictions of endodormancy release and flowering success and facilitate the development of climate-resilient apricot cultivars and adaptive orchard management strategies under global warming.