Genetic dissection of the volatilome-fruit texture interplay in apple

Fruit quality is achieved through the combination of several principle quality factors guiding the consumers' preferences. Among them, fruit texture and aroma play major roles. In this study, we aimed to decipher the genetic interplay underlying these two quality features, using a collection of 162 apple accessions employed to assess both fruit texture (through a TAXT-AED texture analyzer device) and the volatilome (by Proton Transfer Reaction - Time of Flight - Mass Spectrometry instrument). The array of phenotypic entities identified in this survey was further integrated into a GWAS analysis together with 9142 SNP markers genotyped with the 20K Illumina Infinium SNP Array. The marker-trait association analysis identified important co-location between QTLs and relevant candidate genes involved in VOC biosynthetic pathways, such as MdAAT1 and MdIGS. The joint integration between the fruit texture and the volatilome through a multiple factor analysis shed light on a contrasting behavior between these two quality aspects. The implementation of the first two principal components led to the identification of two QTLs, located on chromosome 10 and 2, respectively. The subsequent characterization of the apple varieties based on the allelic configuration of two genes, such as MdPG1 and MdACO1, highlighted the genetic interplay existing between fruit texture and VOC production in apple fruit. The genetic control was furthermore validated through a candidate gene transcriptomic approach, revealing a physiological response associated to a determined allelic state of a specific set of ripening-related genes.