Page 198 - PC2019 Program & Proceedings

PLANT CANADA 2019

S181. Identification of founding accessions and patterns of relatedness and inbreeding derived from
historical pedigree data in a white clover (Trifolium repens L.) and red clover (Trifolium pratense
L.) germplasm collection in New Zealand.
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Egan, L. ; R. Hofmann ; B. Barrett ; K. Ghamkhar ; V. Hoyos-Villegas
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1 Lincoln University; AgResearch; McGill University
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White clover (Trifolium repens) is the most common pasture legume in New Zealand, where it is usually
grown with perennial ryegrass in swards and grazed in situ. Red clover (Trifolium pratense) is grown
worldwide as a fodder crop and used as silage and hay. In a grazing system it is often mixed with white
clover in pasture mixes. The objectives of this study were to identify patterns in Trifolium breeding
programs and to produce an overview of these patterns across time. A pedigree map was used to visualise,
and cluster analysis was used to describe population structure and genetic diversity in white and red
clover germplasm stored in the Margot Forde Germplasm Centre in Palmerston North, New Zealand.
Relatedness and inbreeding coefficients were derived for both species. The overall relatedness was
k=0.002 and overall inbreeding was 0.39% for white clover, and k=0.005 and 0.56% for red clover,
respectively. Relatedness and inbreeding coefficients revealed distinct germplasm pools formed across
time that are of interest to pre-breeding efforts. Founding and influencing accessions were identified. A
total of 34 founding accessions were found in the germplasm database from the year 1941, with three
founders having distinct lineages with highly influential parents (C40, C43 and C63). The ‘Type 1’ class
phenotype had a strong impact on the identification of influencing accessions, forming three sub-
population clusters.

Lucy Egan (lucy.egan@agresearch.co.nz)

S182. Early flowering epi-mutants of ‘Royal’ flax.
Booker, H. ; M. House ; L. Young ; A. Vasudevan ; R. Ragupathy ; S. Robinson
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1 University of Saskatchewan; Agriculture and Agri-Food Canada
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Canada is the largest producer and exporter of flaxseed and seeks to improve yields through greater
adaptation to prairie climatic conditions. Target traits include cultivars that flower early regardless of day
length and result in earlier maturity. Treatment with 5-azacytidine (which alters DNA methylation
patterns) resulted in earlier flowering variants (RE) in the oilseed variety Royal (RC) that is stably
inherited through meiosis. Short day/long day transfer studies demonstrate the RE lines are significantly
less photosensitive than their progenitor RC line and commercial flax cultivars. Gene expression analysis
in leaves indicates the RE lines express FLOWERING LOCUS T (FT) earlier and at higher levels than RC
lines despite sharing the same genotype. To understand factors controlling the new variation, flowering
time was scored in a population of recombinant inbred lines derived from a cross between the RC/RE2
parents. Whole genome resequencing and bisulfite sequencing of the parents and early and late flowering
bulks revealed quantitative trait loci (QTL) and differentially methylated regions associated with the
variation, with the largest QTL detected on chromosome 12. Transcriptome examination (RNASeq) in the
RC and RE2 parents revealed differentially expressed flowering time genes as early as 10 days after
planting, with many annotated in the vernalisation and photoperiod pathways. We will report on progress
to identify the cause of the early flowering trait in RE2 and agronomic consequences.

Helen Booker (helen.booker@usask.ca)

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