Mapping a mutation causing pale yellow petals in Brassica rapa

Petal color is an important trait for both ornamental purposes and also for attracting pollinators. Here, we report a mutation of Brassica rapa R-o-18 with pale yellow petals that we retrieved from an EMS population and named whiter shade of pale (wsp). Phenotypic segregation ratio of an F2 mapping population indicates the phenotype is controlled by a single recessive gene. Mapping data from the whole genome sequencing coupled with allele frequency analysis suggests the mutation is located in a [~]2 Mbp interval on chromosome 2. The interval contains a putative esterase/lipase/thioesterase protein previously demonstrated to account for floral color in B. rapa. We demonstrate that wsp carries a G to A missense mutation causing an aspartate to asparagine substitution within the putative lysophospholipid acyltransferase domain.