Linkage Mapping Of Qtl For Seed Yield, Yield Components, And Developmental Traits In Pea

Seed yield in pea (Pisum sativum L.) is a physiologically complex trait that is strongly influenced by both genotype and environment. Seed yield can be described in terms of its components, which include plant number per unit area, seed weight, and seed number. These yield components show interdependence and plasticity in response to environment; therefore, selection based on a single component is unlikely to succeed in increasing yield in breeding programs. To improve our understanding of the genetic basis of seed yield determination in pea and to identify genetic loci involved, quantitative trait loci (QTL) for yield per se, yield components (seed weight, seed number, and harvest index [HI]) and developmental traits (node of first flower [NFF], number of flowering nodes [NFN], total node number [TNN]) were mapped. The QTL mapping was conducted using F-2-derived families of a cross between Primo, a marrowfat cultivar, and OSU442-15, a blue pea breeding line. Linkage maps containing 108 loci on 11 linkage groups (LGs) were constructed for 227 families derived from this cross. Traits were measured in three replicated field trials conducted in New Zealand during the summers of 1997-1998, 1998-1999, and 2002-2003. The trials were managed to ensure maximum expression of yield potential. The QTL affecting yield-related traits were associated with 19 genomic regions on LGs I, II, III, IV, VI, and VII. The QTL for different yield-related traits were colocalized, suggesting some basis for understanding the reproductive plasticity that is observed in pea at the genetic level.