Geographical patterns of isozyme variation in Mediterranean populations of perennial ryegrass

Balfourier, François; Charmet, G.

doi:10.1038/hdy.1994.6

Cited by 19 publications

(10 citation statements)

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“…This human‐mediated long‐distance gene flow may therefore be responsible for the observed genetic similarity between geographically separated populations. Similarly, Balfourier & Charmet (1994) suggested that the historical long‐distance movement of L. perenne from Italy to Corsica, for agricultural use, was responsible for the current genetic similarities between these populations.…”

Section: Discussionmentioning

confidence: 99%

“…However, this is likely to vary greatly between agriculturally important grasses, which experience considerable amounts of seed movement, and species less interfered with by man. The majority of studies of population‐level genetic variation within grasses have looked at those species important to agriculture which are widely sown as forage, such as perennial ryegrass ( Lolium perenne ) ( Hayward et al ., 1978 ; McNeilly & Roose, 1984; Balfourier & Charmet, 1994). Knowledge of gene flow in grasses is dominated by studies of agricultural situations ( Copeland & Hardin, 1970) or from experimental blocks ( Griffiths, 1950; Gleaves, 1973; Giddings et al ., 1997 ).…”

Section: Introductionmentioning

confidence: 99%

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Genetic structure in the perennial grasses Lolium perenne and Agrostis curtisii

et al. 1998

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Genetic variation was studied in unimproved grassland populations of two contrasting outbreeding perennial grass species. A total of 27 populations of Lolium perenne (perennial ryegrass) and 30 populations of Agrostis curtisii (bristle‐leaved bent), sampled from seven and five regions spread across southern Britain, were assessed at three and four isozyme loci, respectively. The extent of genetic structure within and among populations was estimated using unbiased F‐statistics. In A. curtisii, a nonagricultural species, populations from adjacent regions were found to be more genetically similar than those separated by greater distance. The reverse situation was observed within L. perenne, a species of major agricultural importance. It is suggested that the absence from L. perenne of the pattern of genetic variation found in A. curtisii is consistent with the occurrence of large‐scale human‐mediated gene flow via ‘improved’ ryegrass cultivars. If this is the case, then the disruption of natural patterns of genetic variation by the introduction of nonlocal genotypes may occur without apparent major ecological consequences.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Genetic structure in the perennial grasses Lolium perenne and Agrostis curtisii

et al. 1998

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“…Allozyme diversity studies in Lolium have already been carried out on limited regional samples, e.g. 37 populations from the United Kingdom ( Hayward, 1985), 60 populations from France ( Charmet et al ., 1993 ), 24 from Italy and Corsica ( Balfourier & Charmet, 1994) and, more recently, a sample of 20 populations from Great Britain and Central Europe ( Fernando et al ., 1997 ). However, these studies only concerned L. perenne and thus they did not provide any insight about the origin of this species and its relationships with L. rigidum .…”

Section: Introductionmentioning

confidence: 99%

Genetic differentiation within and between natural populations of perennial and annual ryegrass (Lolium perenne and L. rigidum)

1998

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Genetic structure of 120 wild populations of Lolium perenne and 50 populations of L. rigidum was studied using starch gel electrophoresis. Allelic frequencies were obtained from 12 polymorphic isozyme loci. Gene diversity indices (number of alleles (A), observed (Ho) and expected (He) heterozygosity) were significantly higher in L. rigidum (A=3.13; Ho=0.369; He=0.405) than in L. perenne (A=2.72; Ho=0.308; He=0.322). For both species, most of the diversity appeared to be within populations (GST=0.110 and 0.170 for L. perenne and L. rigidum, respectively). Despite this weak genetic differentiation, significant patterns of geographical variation for diversity indices and allele frequencies were observed in L. perenne populations; the three genetic indices (A, Ho, He) showed the same trend of variation, with the lowest values in the north‐west part of the distribution area (United Kingdom, Ireland) and the highest ones in the south‐east (Turkey, Lebanon, Cyprus, Iraq, Iran). In the same way, as indicated by logistic regression analyses between allelic frequencies and geographical data of L. perenne populations, the latitudinal gradient of allelic frequencies appeared to be more pronounced, although significant relationships also existed with longitude. In contrast, no spatial organization of the diversity was detected in L. rigidum. Hypotheses concerning the taxonomic relationships and the genetic and geographical origins of the two species are discussed. Lolium perenne could be derived from a small bottleneck of L. rigidum populations in the Middle East, and its present distribution area in Europe could be explained either by the extension of primitive agriculture from the fertile crescent, or as a consequence of postglacial recolonization from southern refugia.

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“…At present, isoenzyme markers have been proposed for varietal description of ryegrass (Hayward and McAdam 1977;Greneche et al 1991) and the description of genetic resources (Balfourier and Charmet 1994). However, these markers are of limited utility relative to the increasing number of cultivars.…”

Section: Introductionmentioning

confidence: 99%

Grass consensus STS markers: an efficient approach for detecting polymorphism in Lolium

Lem

Lallemand

2003

Theor Appl Genet

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For ryegrass and many forage crops, characterization of varieties is often difficult for two reasons: few of discriminant morphological traits and a great within-varieties variation. Futhermore, few molecular markers are publicly accessible. In this paper we describe two approaches for the development of 42 sequence-tagged-site (STS) markers. Firstly, 14 STS markers were developed from Lolium sequences found in data bases. Secondly, 28 STS markers were developed from sequences found in related species of Gramineae. Out of 42 STS markers developed, 85.8% yielded successfull amplification and 62% revealed a high level of polymorphism with an average of five alleles per locus. The analysis of amplicons reveals a high STS marker specificity, a high conservation in gene structure and a strong intron sequence homology between allelic forms. Moreover, the majority of the STS markers can be considered as "universal markers" because 81% of these STS markers amplified successfully across 20 related grass species. These results permit us to consider the use of these markers in synteny studies.

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Geographical patterns of isozyme variation in Mediterranean populations of perennial ryegrass

Cited by 19 publications

References 20 publications

Genetic structure in the perennial grasses Lolium perenne and Agrostis curtisii

Genetic structure in the perennial grasses Lolium perenne and Agrostis curtisii

Genetic differentiation within and between natural populations of perennial and annual ryegrass (Lolium perenne and L. rigidum)

Grass consensus STS markers: an efficient approach for detecting polymorphism in Lolium

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