Conservation of allelic multiplicity and genotypic frequency by pooling wild populations of perennial ryegrass

Abstract

Three experimental breeding populations, created by pooling four to five natural populations of perennial ryegrass, were used to indicate the effect of sampling and pooling on the retention of genetic variation. Conservation of allelic multiplicity and genotypic frequencies was observed using allelic frequencies measured on six isozyme markers. We observed that by bulking four or five natural populations, represented respectively by 25 or 20 plants, in a large polycross design, the allelic and genotypic frequencies of the original mother-plants were conserved. There was no loss of rare alleles (0.01 <p <0.10) in the three experimental populations compared with the original natural populations. Only very rare alleles (p <0.01) were reduced in frequency or lost. The value of such a bulking approach is discussed and presented as a possible alternative to the core collection approach to the management and use of genetic resources of perennial ryegrass.

Enhancement of yield and persistence of perennial ryegrass inoculated with one endophyte isolate in France

“…The population size used to re-create the E.I. version of each cultivar was considered to be sufficient to avoid genetic drift and allowed the allelic diversity to be maintained [3,16,19]. It can thus be considered that the E.I.…”

Development of natural late blight epidemics in pure and mixed plots of potato cultivars with different levels of partial resistance

“…Cultivar mixtures have been primarily considered as a means of preserving resistance, either by enhancing the durability of race‐specific resistance genes (Wolfe, 1984; Wolfe, 1985) or by providing a dynamic way to manage genetic resources (Allard, 1990; Reinhold et al ., 1990; Balfourier et al ., 1994; Le Boulc’h et al ., 1994). Enhancing the durability of disease resistance is also a problem in pathosystems which do not comply with the theoretical criteria for success of genotype mixtures, such as those involving broadleaved plants with total or partial resistance.…”

Conservation of genetic diversity in regenerated landraces of Italian ryegrass

“…This was considered to yield a sample of seeds representative of the original panmictic population (Tyler et al, 1984). Balfourier et al (1994) observed a loss of rare alleles in L. perenne in a sample of 16 -25 plants in a polycrossing trial, although the loss was compensated by a random increase in the frequency of these alleles in the other accessions within same group, producing a 'buffer effect'. However, there is a risk of the loss of some of this variability during the regeneration of accessions.…”

“…Balfourier et al (1994) used isoenzyme analysis to study how the method of creating experimental populations affects the conservation of allele and genotypic frequencies in natural populations of perennial ryegrass (Lolium perenne L.). Balfourier et al (1994) used isoenzyme analysis to study how the method of creating experimental populations affects the conservation of allele and genotypic frequencies in natural populations of perennial ryegrass (Lolium perenne L.).…”

“…In the case of allogamous species with anemophilous pollination, there is little information about how the allele frequencies and agronomic characteristics of populations are affected by the method of regeneration used in the germplasm banks. Balfourier et al (1994) used isoenzyme analysis to study how the method of creating experimental populations affects the conservation of allele and genotypic frequencies in natural populations of perennial ryegrass ( Lolium perenne L.). Johnson (1998) also used isoenzyme analysis to investigate the genetic structure of populations of Italian ryegrass regenerated in different ways.…”