A QTL Analysis of White Clover Seed Production

Abstract

proved white clover in paddocks (Pederson and Brink, 2000). White clover (Trifolium repens L.) exhibits complex inheritanceSeed yield is a complex character showing continuof seed production potential. Genome maps allow plant breeders to ously distributed values, typical of multigenic control dissect the genetic control of complex traits into discreet factors with with environmental influences on trait expression. Sev-Mendelian inheritance, each of which is called a quantitative trait locus (QTL). A pair-cross between two highly heterozygous white eral component traits influence SY in white clover. Seed clover genotypes created an F 1 mapping population (n ϭ 182) used to yield is the product of ID and YI. Yield per inflorescence investigate the genetic control of seed yield (SY) and three component is itself a product of variation in seed size and density traits: inflorescence density (ID), yield per inflorescence (YI), and (measured as TSW), floret number per inflorescence, thousand-seed weight (TSW). Analysis of 3 yr of field data from a and floret fertility. The use of increased YI rather than replicated trial in the primary seed production region of New Zealand increased ID may be a preferred strategy to boost SY indicated no strong correlations among the component traits. The in white clover. Each inflorescence is at the cost of ANOVA indicated significant genotype, year, and genotype ϫ year a stolon, suggesting that types with high inflorescence effects for SY, ID, and YI; and genotype and genotype ϫ year effects numbers will have compromised on-farm persistence. for TSW. Using genotype data for 209 microsatellite loci in the allo-The balance between SY potential and forage perfortetraploid genome, the multiple QTL model analysis resulted in the mance potential is yet to be clearly defined. Annicchiardiscovery of 23 QTLs related to seed production in white clover. ico and colleagues (Annicchiarico et al., 1999) report a Both parent plants harbored beneficial alleles for SY and the three component traits. A region of the genome at the distal end of linkage

Achievements and Challenges in Improving Temperate Perennial Forage Legumes

“…QTL analysis identified two genome regions harbouring major QTL (Barrett et al, 2005b). Subsequent analysis revealed substantial effects in a number of breeding material surveyed with markers sourced from those genome regions, with 8 out of the 12 populations surveyed showing marker effects accounting for a mean 38% differential in seed yield (Barrett et al, 2009), leading to targeted application of the marker assay in selecting for seed yield in white clover breeding populations.…”

“…Persistence has also been mapped in red clover (Herrmann et al, 2008;Klimenko et al, 2010). In white clover, QTL discovery for traits has included spaced plant morphogenesis in an F 2 inbred population in the absence of grass competition and grazing , seed yield on spaced plants ( Barrett et al, 2005b), salt tolerance (Wang et al, 2010), and stolon diameter, stolon number, and internode length (Zhang et al, 2010). White clover full-sib pair cross mapping populations have been assessed for aerial and root morphological characters (Jahufer et al, 2008;Jahufer et al, 2013) but have not yet had QTL discovery reported.…”

Future options and targets for pasture plant breeding in New Zealand

“…which may be introgressed into white clover (Barrett et al 2005a) and Qtl targeting both seed and vegetative production traits in white clover (Barrett et al 2005b;Cogan et al 2006). As axillary buds of white clover can produce either a new stolon or a flower, the propensity to flower is inversely related to plant persistence which is dependent on the production of new stolons.…”

“…this is a first step in the development of MAs for use in white clover breeding. Significantly, a candidate gene has been identified as a perfect marker which can improve the potential for this Qtl to be targeted to improving seed production in unrelated populations (Barrett et al 2005b).…”

Validation of in silico-predicted genic SNPs in white clover (Trifolium repens L.), an outbreeding allopolyploid species

“…Enrichment of genetic maps with common marker systems will permit more detailed trait-dissection studies and comparison with pre-existing quantitative trait locus (QTL) detection data for equivalent traits, such as studies of vegetative morphogenesis, reproductive morphogenesis and reproductive development based on the F 2 (I.4R £ I.5J) populations ) and seed yield components based on the F 1 (Sustain 6525-5 £ NRS 364-7) population (Barrett et al 2005). The gene-associated SNPs described here are likely to be of highest value as anchor markers for enhanced construction of genetic maps, rather than as functionally-associated markers for direct allele selection.…”