title: Identifying genetic components controlling fertility in the outcrossing grass species perennial ryegrass (Lolium perenne) by quantitative trait loci analysis and comparative genetics.
abstract: Mutational load and resource allocation factors and their effects on limiting seed set were investigated in ryegrass by comparative mapping genomics and quantitative trait loci (QTL) analysis in two perennial ryegrass (Lolium perenne) mapping families sharing common genetic markers. Quantitative trait loci for seed-set were identified on chromosome (LG) 7 in both families and on LG4 of the F2/WSC family. On LG7, seed-set and heading date QTLs colocalized in both families and cannot be unequivocally resolved. Comparative genomics suggests that the LG7 region is syntenous to a region of rice LG6 which contains both fertility (S5(n)) and heading date (Hd1, Hd3a) candidate genes. The LG4 region is syntenous to a region of rice LG3 which contains a fertility (S33) candidate gene. QTL maxima for seed-set and heading date on LG4 in the F2/WSC family are separated by c. 8 cm, indicating distinct genetic control. Low seed set is under the control of recessive genes at both LG4 and LG7 locations. The identification of QTLs associated with seed set, a major component of seed yield in perennial ryegrass, indicates that mutational load associated with these genomic regions can be mitigated through marker-assisted selection.
authors.affiliation: Plant Genetics and Breeding Department, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK.
authors.forename: I P
authors.initials: IP
authors.lastname: Armstead
authors.forename: L B
authors.initials: LB
authors.lastname: Turner
authors.forename: A H
authors.initials: AH
authors.lastname: Marshall
authors.forename: M O
authors.initials: MO
authors.lastname: Humphreys
authors.forename: I P
authors.initials: IP
authors.lastname: King
authors.forename: D
authors.initials: D
authors.lastname: Thorogood
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D017343:Genes, Plant; D005819:Genetic Markers; D014644:Genetic Variation; D008129:Lolium / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics*; D012098:Reproduction / Q000235:genetics
chemical_list: D005819:Genetic Markers