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The biological basis of Stone Fruit (Prunus spp.) Quality: a functional and comparative Genomic Approach

Final Activity Report Summary - PRUNOMICS (The Biological Basis of Stone Fruit (Prunus spp.) Quality: a Functional and Comparative Genomic Approach)

The primary objective of the project was the gene discovery in Prunus species by utilising a peach oligo-microarray in a heterologous fashion. Thus, considering the high degree of sequence conservation within the Rosaceae family and, in particular, among the Prunus species we employed the first available peach oligonucleotide microarray (µPEACH 1.0) developed by the ESTree consortium where the hosting lab is an active member, for the investigation of transcription profile in peach, apricot and plum fruits during their ripening (on- and off-tree), as well as for comparative trancriptomic studies in cultivars of the same species with different ripening properties, mainly in terms of ethylene production, or to cultivars subjected to various postharvest treatments, such as different temperatures during their ripening or cold storage or application of compounds with ethylene-antagonistic action.

In particular, transcriptomic studies were carried out in two peach genotypes showing diverse properties in terms of ripening pattern and postharvest behaviour; results illustrated that stony hard peaches, characterised by lack of ethylene evolution at ripening, recover the ability to synthesise ethylene when exposed to postharvest temperature stress and this has been exploited to elucidate the role of the hormone in gene expression regulation in ripening peaches. When the peach microarray was employed for transcriptomic studies in apricot and plum fruit, results indicated that this platform can be successfully applied in related, yet phenotypically distinct, species belonging to the Prunoideae sub-family, where few or no genomic data are available.

This approach provided an overview of genes differentially transcribed during apricot and plum fruit ripening both on- and off-tree, as well as to compare the transcriptomic profile of plum cultivars with different ripening properties and/or subjected to different postharvest treatments. Such data were processed in order to unravel mechanisms and to identify key genes differentially expressed and to correlate their behaviour with traits of agronomic interest. Special reference was given to ethylene-related genes, auxin (AUX/IAA) regulated genes and genes encoding for heat shock proteins. Another perspective of the project was to elucidate common and divergent processes regulating stone-fruit development, thus contributing to the understanding of the evolutionary mechanisms within the Prunus species.

This functional genomics approach of the biological basis of peach and other Prunus species, like apricot and plum, fruit quality as a concept is novel and equally novel is the experimental strategy that was proposed and applied for the needs of the current project. Our results have been giving insight and new direction in defining the ripening syndrome in stone-fruits. The main achievement of the project was to form a skilled member of the scientific community, trained under a research program of paramount importance, from which he gained knowledge, experience and ideas, in order to carry on research studies in the field of functional genomics applied to fruit science with emphasis on postharvest physiology.