|Ma, Yu - Washington State University|
|Myers, James - Oregon State University|
|Mazourek, Michael - Cornell University - New York|
|Coyne, Clarice - Clare|
|Main, Dorrie - Washington State University|
|Wang, Meinan - Washington State University|
|Humann, Jodi - Washington State University|
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2016
Publication Date: 7/13/2016
Citation: Ma, Y., Hu, J., Myers, J., Mazourek, M., Coyne, C.J., Main, D., Wang, M., Humann, J., Mcgee, R.J. 2016. Development of SCAR markers linked to sin-2, the stringless pod locus in pea (Pisum sativum L.). Molecular Breeding. doi: 10.1007/s11032-016-0525-4.
Interpretive Summary: Peas are important grain and vegetable legume crops. Snow peas and snap peas differ from other peas in that the pods as well as the seeds are consumed. Snap pea pods possess three important characteristics: the pod walls have very little parchment, the pod walls are thick, and there is no string in the sutures of the pods. Stringless pods are especially important in snap peas as the pods are consumed a a more mature stage and the string has had time to develop. Stringlessness has been a very difficult triat to breed. It is controlled by a single recessive gene, however segregation in the F2 generation does not follow a consistent pattern and far fewer than expected stringless segregants are recovered. In breeding programs, the unusual segregation pattern has hindered the progress of improving stringless snap peas as a very large F2 population is required to identify a sufficient number of stringless plants to advance to the next generation. Developing DNA markers associated with this trait will expedite the genetic improvement of snap pea since the marker would allow the identification of desirable genotype at the seedling stage. This paper reports the results of identifying TRAP markers linked to the sin-2 gene in pea and converting them to breeder-friendly SCAR markers.
Technical Abstract: With increasing consumer demand for vegetables, edible-podded peas have become more popular. Stringlessness is one of most important traits for snap peas. A single recessive gene, sin-2, controls this trait. Because pollen carrying the stringless gene is less competitive than pollen carrying the stringy gene, there are fewer than expected stringless plants recovered in segregating generations. Marker-assisted selection (MAS) is a valuable tool to identify plants with the traits of interest at an early stage in the breeding process. The objective of this study was to identify robust, user-friendly molecular markers tightly linked to sin-2. A total of 144 target region amplification polymorphism (TRAP) primer combinations were used to screen four DNA bulks, which were constructed from 32 pea breeding lines based on their phenotypes. Sixty polymorphic TRAP primers combinations were identified between bulks of stringless and stringy pods. Five of them, F6_Trap03_168, F6_SA12_145, F10_ODD8_130, F11_GA5_850 and F12_SA12_190, showed more than 90% association with the stringless phenotype in 32 pea breeding lines. Two of the TRAP markers, F10_ODD8_130 and F12_SA12_190, were cloned, sequenced and successfully converted to sequence characterized amplified region (SCAR) markers. These two SCAR markers were validated using 20 F5 recombinant inbred lines derived from a cross between Bohatyr (a dry pea variety with strings) and S1188 (a stringless snap pea variety) and showed strong marker-trait association. The results will have direct application in marker-assisted selection of stringless edible-podded peas.