Comparative QTL Mapping for Seed Weight Between Ryegrass and Cereals.

COMPARATIVE QTL MAPPING for SEED WEIGHT BETWEEN RYEGRASS (LOLIUM spp) and CEREALS

Inoue M, R. Brown, R. Barker, M. Casler, and G. Jung

         Seed weight is one of the most important, complex traits in breeding and the domestication process for several major food crops, e.g. rice (Oryza sativa L.) and wheat (Triticum aestivum L.). Comparative mapping studies provide insight into the evolution of genome organization within species and aid in understanding important traits conserved during the domestication process. It is important to investigate the genetics underlying these conserved traits. We determined the net weight of 100 seeds for each of the progenies in an annual (Lolium multiflorum Lam.) × perennial ryegrass (L. perenne L.) interspecific hybrid population (MF population). A well-saturated linkage map for Lolium (2n=14), previously constructed from the same population using heterologous restriction fragment length polymorphism (RFLP) probes was used for comparative analysis of 100-seed weight quantitative trait loci (QTL) between ryegrass and cereals. The plants were grown in different geographical locations (Oregon and Wisconsin) and years (2000, 2001, and 2005). Two seed weight QTL were identified on linkage groups 2 and 4. These QTL were associated with variations for seed width and seed length in this population. Our results also indicated that ryegrass seed weight QTL are on syntenic chromosomal regions of rice and wheat where QTL for seed weight related traits have been previously detected. This result suggests that those QTLs might have remained conserved despite different intensities of domestication.