Genetic Mapping of Bolting QTL in Bulb Onion (Allium cepa)

Onion is a biennial plant producing bulbs in the first year and flowering in the second. Flowering in the first season is known as bolting and is undesirable for bulb production. Adaptation of onion varieties to produce bulbs and flowers in certain environments with particular photoperiod and temperature conditions limits the ability to distribute and introduce new germplasm into existing elite lines. A study was undertaken using doubled haploids and a wide (short-day x long-day) cross to further interrogate the flowering time pathways, to identify markers that could be used for marker assisted selection (MAS) in breeding programmes to allow integration of exotic germplasm and to select against bolting susceptibility. As part of this study a next-generation sequencing resource of the transcriptome of the parents of the mapping population and tools were developed to exploit the data for mass marker design and re-sequencing of candidate genes. Quantitative trait loci (QTL) and evidence of selection were detected and will be discussed.