Investigation of random amplified polymorphic DNA (RAPD) as markers for soluble solids in onion

Bulbing onions (Allium cepa L.) are one of the widely consumed vegetables in the United States. They are consumed fresh in salads, dehydrated to produce chips and powder which are used to enhance flavor of processed foods, and stored to use during the off-season. The multiple uses of onions are dependent upon the composition of soluble solids which are an economically important quality factor for both growers and processors.

Typically, soluble solids in onion are improved using traditional breeding techniques which dependent upon selection. Selection based upon the phenotype is laborious and time consuming. Molecular markers have provided a valuable tool to improve the pace of selection in breeding programs. One such marker that is suitable to assist in the selection process in breeding is random amplified polymorphic DNA (RAPD).

The purpose of this study was to investigate the utility of RAPDs as markers to screen for soluble solids in onion. This goal was accomplished by comparing four DNA extraction protocols and by contrasting two DNA polymerases to generate reliable RAPD profiles. Suitable protocol and polymerase were selected and were then used to generate and compare RAPD markers in two pooled DNA bulks which comprised of low and high soluble solids. DNA polymorphisms are generated and used as markers to tag and identify economically important traits such as soluble solids in onions. The application of RAPDs play a vital role in developing soluble solids onion cultivars.