Genetic Determinants of Crop Timing and Quality Traits in Two Interspecific Petunia Recombinant Inbred Line Populations

The rate at which plants develop new nodes (development rate) is a major determinant of crop production time, yet the genetic control of this process, including genetic interactions with crop quality parameters, is poorly understood. We employed a modified genotyping-by-sequencing approach and generated genetic linkage maps with 6,291 and 3,297 single nucleotide polymorphisms (SNPs) for the interspecific Petunia recombinant inbred line (RIL) population - P. axillaris x P. exserta (AE) and P. integrifolia x P. axillaris (IA), respectively. Comparative mapping between the populations revealed perfect collinearity of marker order but different recombination frequency at the corresponding linkage groups (LGs). Quantitative trait loci (QTL) mapping conducted for development traits and other important quality traits indicated QTL clustered on chromosome 1, 2, 4 and 6 for the AE population and chromosome 1, 2, 5 and 6 for the IA population. Additionally, 209 differentially expressed unique transcripts were identified in shoot apex tissue between fast- and slow-developing RILs, 13 of which mapped to within 1 cM of a development rate QTL. These results will facilitate the identification of novel genes controlling crop timing and quality traits in Petunia and highlight the power of using multiple interspecific populations to elucidate genetic determinants of natural variation.