Genetic Determinism of Chilling and Heat Requirements and Flowering Date, Three Phenological Traits Highly Affected By Climate Change in Sweet Cherry

In sweet cherry (Prunus avium L.), flowering efficiency is critical for productivity. This process is under the control of a complex mechanism involving the fulfilment of chill and heat requirements. Knowledge on the genetic determinism of flowering traits is becoming crucial to anticipate the increasing of ecological misalignment of adaptative traits with future climate conditions in most temperate-fruit species.

Chilling and heat requirements were evaluated over three years and flowering date over five years in an intraspecific sweet cherry F₁ progeny. In addition, flowering date was evaluated over six years in a second F₁progeny. One QTL with major effect and high stability between years of evaluation was detected for chilling requirements and flowering date on the same region of linkage group 4. For heat requirements no stable QTL was detected. Candidate genes underlying the major QTL on LG4 were investigated and key genes were identified for chill requirements and flowering date.

Phenotypic dissection of flowering date and year-repetitions let us identify chilling requirements as the high heritable component of flowering date and a high interaction genotype x environment for heat requirements. QTLs for chilling requirements reported in this study are the first described in this species. Our results provide a basis for the identification of genes involved in chilling requirements and flowering date that could be used to develop ideotypes adapted to future climatic conditions.