Identification and Validation of Candidate Genes Affecting Volatile Compounds in Strawberry Fruits

Strawberry fruit flavor is the result of a complex mix of sugars, acids, and volatile organic compounds (VOCs) synthesized from a wide range of precursors including amino acids, fenylpropanoids and fatty acids. Improvement of strawberry flavor while maintaining other important traits, such as agronomic and postharvest life, requires understanding the complexity of volatile biosynthesis. We have identified genomic regions controlling the content of several VOCs using the 232 x 1392 segregating population. In order to identify the genes responsible for the variation in some of these VOCs, we are undertaking a RNA-seq approach in selected lines of the 232 x 1392 population and by sorting RNA-seq data from a second population, Mara x Elyana, based on the content of the selected VOCs. For a cluster of four phenyl-derived esters and g-dodecalactone, in LG I-1 and LGVII-1, we have identified 3 candidate genes and are using qRT-PCR, eQTL analysis and transient RNAi-induced silencing in fruits to validate their involvement. The largest cluster of QTLs controlling 16 different volatiles was mapped to LG VI-1. We have selected two contrasting bulked pools of fruits from 10 lines each with high and low levels of the six esters with QTL with stable effects higher than 30%. To identify the determinants of these variations we aim to identify differentially expressed genes between the pools using illumina RNA-seq. Preliminary results will be presented.