Postharvest texture change is a fundamental question for fruit growers and breeders as it drives consumer acceptability. To decipher the genetic control of fruit texture, we studied an apple segregating population over 2 years at harvest and after 2 months of cold storage. Texture complexity was dissected in quantitative traits, related to (i) sensory perception of fruit quality and (ii) fruit mechanical properties. Genetic models including storage, genotype and their interaction effects were built. After selection of a model, broad sense heritabilities were estimated. Strong genetic and storage effects were identified for all texture traits with significant interaction. Moreover, the structure of traits co-variations was preserved after storage. Based on the new integrated genetic map, numerous quantitative trait loci (QTLs) were detected, revealing multigenic control of fruit texture traits. QTLs were clustered according to the kind of texture assessment i.e. penetrometry, compression and sensory. Moreover, QTL stability over years and storage periods was investigated. Lastly, a short list of relevant texture traits, such as fruit global hardness and fruit deformation until skin failure, is proposed to optimize texture phenotyping for future quantitative genetic studies

Superficial scald is one of the most serious postharvest physiological disorders that can affect apples after a prolonged cold storage period. This study investigated the impact of pre-and post-harvest climatic variations on superficial scald in a susceptible apple cultivar. Fruit batches with contrasting phenotypes for superficial scald incidence were identified among several years of "Granny Smith" fruit production. The "low scald" year pre-harvest climate was characterised by a warm period followed by a sudden decrease in temperature, playing the part of an in vivo acclimation to cold storage. This was associated with many abiotic stress responsive genes which were induced in fruit peel. In particular 48 Heat Shock Proteins (HSPs) and 5 Heat Shock transcription Factors (HSFs) were strongly induced at harvest when scald incidence was low. For "high scald" year, a post-harvest acclimation of 1 week was efficient in reducing scald incidence. Expression profiles of stress related genes were affected by the acclimation treatment and indicate fruit physiological adaptations to cold storage. The identified stressresponsive genes, and in particular HSPs, could be useful indicators of the fruit physiological status to predict the risk of scald occurrence as early as harvest. Scientific RepoRtS |(2020) 10:6180 | https://doi.

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