S01 - Session P4 - Development and comparison of phenotypic methods for colour assessment and polyphenolic composition evaluation in red flesh apples

Authors: Pierre Bouillon *, Anne-Laure Fanciullino, Sandrine Balzergue, Sylvain Hanteville, Etienne Belin, Hélène Muranty, Frédéric Bernard, Jean-Marc Celton

In recent years, red-fleshed apple varieties have received increased attention from consumers for their enjoyable aspect. This trait is intimately linked with anthocyanin accumulation in the fruit flesh, which are known for their antioxidative and beneficial effects on human health. Our project aimed to: (i) develop high-throughput methods for characterizing fruit flesh colour (intensity and spatial distribution), and (ii) identify genetic and epigenetic markers associated with the development of this trait. Our analysis was performed on 385 individuals derived from 5 segregating F1 populations. Different destructive and non-destructive techniques were compared to quantify fruit flesh colour based on VIS-imaging, hyperspectral imaging and VIS-NIR spectroscopy. The goal was to determine discriminant wavelengths to quantify fruit flesh colour and to develop robust phenotyping methods for colour intensity and distribution measurements. These methods have also been used for the monitoring of internal browning in fruit, which often occurs during storage and leads to the development of undesirable brown patches throughout the fruit flesh. Furthermore, based on HPLC-UV methods a protocol has been developed to quantify secondary metabolites present in the flesh. Variations in phenolic compounds were investigated concomittantly with flesh colour measurements to characterize the correlation between fruit phenolic composition and flesh coloration. The developed precise phenotypic methods for fruit flesh colour measurement is the first step towards the deciphering of the genetic and epigenetic determinism of this trait. QTLs associated with genomic regions controlling the observed traits will be identified and will lead to the development of molecular tools applicable in the breeding of red flesh varieties.