Fans of tomatoes would agree that most store-bought varieties lack flavor. A group of scientists from the Agricultural Research Service (ARS) and the Boyce Thompson Institute has found a solution to the problem of no taste in tomatoes. Scientists have constructed the pan-genome for the cultivated tomato and its wild relatives mapping nearly 5,000 previously undocumented genes.
The pan-genome includes all of the genes from 725 different cultivated and closely related wild tomatoes. The research found that 4,873 genes were absent from the original reference genome. Researchers say that tomatoes today have a narrow genetic base and that the pan-genome helps identify what additional genes beyond the reference might be available for crop breeding and improvement.
Tomato breeders have concentrated on varieties and traits that control yield, shelf life, disease resistance, and stress tolerance. Those traits are economically important to growers. Tomatoes are a fruit, but are considered a vegetable by most and are the second most consumed vegetable in the US after potatoes.
One discovery in the research was a rare form of a gene labeled TomLoxC that influences fruit flavor. The gene influences taste by catalyzing the biosynthesis of several fat-involved volatiles that evaporates easily and contributes to flavor and aroma. The team found a new role for that gene that facilitates the production of a group of apocarotenoids, organic chemicals derived from carotenoids, that work as signaling molecules influencing a variety of responses in plants.
The carotenoids have a variety of floral and fruity odors that are less important in taste. The team found that the rare version of TomLoxC was only found in 2% of older or heirloom cultivated large tomato varieties. The team found that the gene was present in 91% of currant-sized wild tomatoes including Solanum pimpinellifolium, the wild predecessor of the cultivated tomato.