Oak Park Research Center

Carlow, Ireland

Oak Park Research Center

Carlow, Ireland
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Thorogood D.,Aberystwyth University | Yates S.,ETH Zurich | Manzanares C.,ETH Zurich | Skot L.,Aberystwyth University | And 4 more authors.
Frontiers in Plant Science | Year: 2017

Self-incompatibility (SI) is a mechanism that many flowering plants employ to prevent fertilisation by self- and self-like pollen ensuring heterozygosity and hybrid vigour. Although a number of single locus mechanisms have been characterised in detail, no multi-locus systems have been fully elucidated. Historically, examples of the genetic analysis of multi-locus SI, to make analysis tractable, are either made on the progeny of bi-parental crosses, where the number of alleles at each locus is restricted, or on crosses prepared in such a way that only one of the SI loci segregates. Perennial ryegrass (Lolium perenne L.) possesses a well-documented two locus (S and Z) gametophytic incompatibility system. A more universal, realistic proof of principle study was conducted in a perennial ryegrass population in which allelic and non-allelic diversity was not artificially restricted. A complex pattern of pollinations from a diallel cross was revealed which could not possibly be interpreted easily per se, even with an already established genetic model. Instead, pollination scores were distilled into principal component scores described as Compatibility Components (CC1-CC3). These were then subjected to a conventional genome-wide association analysis. CC1 associated with markers on linkage groups (LGs) 1, 2, 3, and 6, CC2 exclusively with markers in a genomic region on LG 2, and CC3 with markers on LG 1. BLAST alignment with the Brachypodium physical map revealed highly significantly associated markers with peak associations with genes adjacent and four genes away from the chromosomal locations of candidate SI genes, S- and Z-DUF247, respectively. Further significant associations were found in a Brachypodiumdistachyon chromosome 3 region, having shared synteny with LoliumLG 1, suggesting further SI loci linked to S or extensive micro-re-arrangement of the genome between B. distachyon and L. perenne. Significant associations with gene sequences aligning with marker sequences on LoliumLGs 3 and 6 were also identified. We therefore demonstrate the power of a novel association genetics approach to identify the genes controlling multi-locus gametophytic SI systems and to identify novel loci potentially involved in already established SI systems. © 2017 Thorogood, Yates, Manzanares, Skot, Hegarty, Blackmore, Barth and Studer.

Gallagher E.,Trinity College Dublin | Douglas C.G.,Teagasc | Kelly D.L.,Trinity College Dublin | Barth S.,Oak Park Research Center | And 2 more authors.
Biology and Environment | Year: 2013

To quantify levels of gene flow among and genetic variation within different age cohorts of pedunculate oak (Quercus robur L.) in a semi-natural oak woodland, diversity and parentage studies were undertaken on a stand in Ballytobin, Co. Kilkenny, Ireland. Trees were categorised into four size classes seedlings, saplings, mature trees and veterans, and genetic differentiation was estimated for three microsatellite markers using AMOVA. Parentage was assessed using a likelihood assignment approach. Between nine and fourteen alleles were detected per locus (mean gene diversity, h, 0.8312). All samples from Ballytobin were heterozygous. AMOVA between age cohorts (veterans, mature, saplings and seedlings) estimated that only 2% of the variation was partitioned among age cohort and the mean FST was low (0.015) but significant (P = 0.034). Parent-pair analysis revealed that out of 24 candidate trees, fifteen were assigned as parents to at least one offspring and, out of these, five were veteran. The average pollination distance was estimated at 47.8m with seven out of the twelve parent-pairs being within 50m of each other. The measured range of distances between trees indicated in the analysis as parents was between 22m and 150m. The highest values for number of parent/offspring assignments were between 40m and 49m. Overall, veteran oak at the site were found to be reproductively successful and a low level of differentiation was found between age cohorts indicating that population genetic diversity has been maintained over time. © ROYAL IRISH ACADEMY.

Lynch T.M.H.,Oak Park Research Center | Lynch T.M.H.,National University of Ireland | Barth S.,Oak Park Research Center | Dix P.J.,National University of Ireland | And 4 more authors.
Agronomy Journal | Year: 2015

Ground-cover assessments of grassland swards provide information on durability and persistence, which in turn relate to disease resistance and competitive ability. These assessments are traditionally performed visually, but digital imaging can provide a more accurate method of ground-cover scoring. Differences in ground cover between late-heading perennial ryegrass (Lolium perenne L.) cultivars in four trials (2 yr of sowing and two sites) were determined using both digital imaging and visual scoring. Ground-cover percentages were calculated from digital images with public-domain soft ware on the basis of color separation of grass leaves from bare soil. For both years of sowing, highly significant interactions of cultivar and site were detected. Significant differences between cultivars were detected in three out of four trials, with diploid cultivars having greater cover than tetraploids in the older trials. Thus digital image analysis of ground cover may be a useful tool in crop improvement and provision of guidelines regarding suitability of a particular cultivar for a particular site. © 2015 by the American Society of Agronomy 5585 Guilford Road, Madison, WI 53711 USA All rights reserved.

PubMed | Oak Park Research Center
Type: Journal Article | Journal: TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik | Year: 2013

Data are presented which indicate that a cytoplasmic/genetic type male sterility has been induced into backcross progeny derived from intergeneric hybridization between Festuca pratensis (female parent) and Lolium perenne. Large numbers of male sterile genotypes have been obtained in all the backcross generations examined. The frequency and purity of maintainer genotypes is low and requires further breeding and selection. Analysis of data suggest that at least two loci are involved in fertility restoration. Conclusions regarding the genetic model are tentative and require further analyses.

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