Peach Dormancy Associated MADS-Box Gene Expression during Natural Chilling Accumulation

摘要

Six MICK~C-type MADS-box transcription factors, designated as Dormancy-Associated MADS-box (DAM) genes, are not expressed in the peach (Prunus persica (L.) Batsch] mutant evergrowing, which fails to cease growth and enter dormancy under dormancy-inducing conditions. One or more of these peach DAM genes have been proposed as candidates for the regulation of growth cessation and terminal bud formation. The proximity or co-localization of peach EVG locus with a QTL associated with a chilling requirementtrait suggests that the DAM genes are also potential candidate genes for this characteristic. Two peach DAM genes (DAM5 and 6) are up-regulated by short days and peak at winter solstice, coincident with the chilling accumulation achievement required forbud break. Reports on homologous of the DAM genes from other species also indicate that these genes could be cold regulated. In this work, we used three cultivars with different chilling requirement to correlate the fulfillment of chilling requirement with the expression of the peach DAM genes. Vegetative terminal and floral buds were sampled from field grown 'Contender' (1050 chilling hours), 'Rubyprince' (850 chilling hours) and 'Springprince' (650 chilling hours) peach cultivars, weekly through winter 2008-2009. Flower bud break potential was evaluated weekly by transferring cuttings to a growth-permissive environment, and bud-burst was scored after 14 days. We used quantitative real time PCR to study the expression of the DAM genes during chillingaccumulation. We also evaluated vegetative bud break and DAM genes expression in Contender under controlled cold exposure. The potential role of the DAM genes in the chilling requirement of peach will be discussed. The material collected will be used for the development of an EST library of bud tissue during chilling accumulation.