Identification of founding accessions and patterns of relatedness and inbreeding derived from historical pedigree data in a red clover germplasm collection in New Zealand.

Pedigree maps were constructed for the accessions of red clover held in the Margot Forde Germplasm Centre (MFGC), New Zealand. Pedigree data from accessions introduced into the MFGC between 1934 and 2016 were used. Data were filtered for accessions with breeding activity. Half- and full- sib family breeding were included. A total of 30 founding accessions were identified in the database. Of these, 25 were categorised as ‘New Zealand Broad’, two were categorised as ‘English Broad’, two were categorised as ‘English Giant Hybrid’ and one was categorised as ‘Cotswold Broad’. The first synthetic form was identified from parents derived from ‘English Broad’ and ‘English Giant Hybrid’. Influencing founder accessions were also identified. A relationship between introductions, relatedness and geographic origin was found. The inbreeding and kinship coefficients were estimated across the population. The maximum number of traced generations was eight. Of the total population, 13.43% of accessions were identified as orphan lines, 71.35% of accessions were identified as terminal lines and 20.44% of accessions had recorded offspring families. A total of 1742 accessions were used in the estimation of relatedness coefficients with a mean relatedness of 0.005. Overall mean inbreeding was 0.56% and 10.68% among the accessions with non-zero inbreeding coefficients. We conclude that red clover diversity has been successfully maintained at the MFGC over the past 80 years.