Body of Abstract: Wild relatives and semi-domesticated germplasm of cultivated plants provide a significant reservoir of genetic diversity for key regulators of quality traits. Future crop improvement relies on harnessing this diversity. However, mining semi-domesticated and wild germplasm for beneficial alleles is not straightforward because fruit quality is typically a quantitatively inherited trait. One critical quality trait is the flavor of produce such as tomato is a combination of taste and smell. Taste is determined by the levels and balance of sugars and acids in the fruit. The smell is thought to be contributed by up to ~ 400 different volatiles that are emitted by the fruit, especially when consuming the produce. We have analyzed the genome sequence and the volatile aroma of a diverse tomato population ranging from fully wild S. pimpinellifolium to fully cultivated S. lycopersicum lycopersicum accessions collectively called the Varitome Collection. GWAS and mapping for one such volatile, methyl salicylate, resulted in the discovery of a new gene that encodes a methyl esterase, responsible for the conversion of methyl salicylate to salicylic acid. The research also showed that the locus encodes up to four methyl esterases and that the genetic variation at the locus is huge, especially in the wild parents S. pimpinellifolium. Mainly driven by genome structural variants, the function of the different methyl esterase haplotypes and interaction with other loci in tomato will be discussed.
This work is funded by NSF IOS 1564366 and IOS 2151032.