S11 - Session P2 - Molecular analysis of bud dormancy regulation by temperature in sweet cherry

Authors: Bénédicte Wenden *, Mathieu Fouché, Hélène Christmann, Xavier Lafon, Armel Donkpegan

Over the past decades, climate change has already led to a higher frequency of mild winters. In particular, the rising temperatures impact winter dormancy, a resting period which is a key step of the tree life cycle, preventing growth under unfavorable conditions. Indeed, the lack of chilling temperatures during dormancy can cause flowering defaults such as bud necrosis whereas the mild temperatures at the end of winter lead to early flowering, desynchronization with pollinators and a higher risk of frost damages. These effects of mild temperatures will contribute to a decrease in fruit production and could have a major economic impact. Sweet cherry trees, in particular, are very sensitive to temperatures; therefore their production is greatly threatened by climate change. In order to better anticipate the effects of future climatic conditions on sweet cherry cultivation, it is necessary to better understand how dormancy is regulated under constrained temperatures. We investigated the effect of warm temperatures on sweet cherry trees during dormancy onset and maintenance, using both phenological observations and molecular analyses. Potted trees of the sweet cherry cultivar 'Regina' were submitted to cold deprivation from July to March, under long days and short days in order to separate the effect of temperature and photoperiod. We recorded the phenological observations through the entire cycle of seasons. Moreover, we performed global transcriptomic analysis using RNA Seq on bud tissues sampled throughout the temperature and photoperiod treatments, in order to highlight candidate genes that are regulated by temperatures during dormancy progression. Our results show that cold deprivation induces a marked delay in the flowering date, and strongly affects the expression patterns of dormancy candidate genes. Further analyses will allow the identification of genes and physiology pathways that are involved in response to temperature.