The frequency of natural cross-fertilization in a composite cross of barley grown in Scotland

Giles, R. J.; McConnell, Gillian; Fyfe, J. L.

doi:10.1017/s0021859600026939

Cited by 5 publications

(5 citation statements)

References 4 publications

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“…In addition, under cool and moist conditions, higher outcrossing rates may be caused by extended pollen viability (Hammer 1977;Lansac et al 1994;Gupta et al 2000). Our results agree with the findings of Giles et al (1974), Brown et al (1978) and Chaudhary et al (1980) who showed that cool and moist conditions promote outcrossing in barley.…”

Section: Influence Of Climatic Conditionssupporting

confidence: 93%

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

et al. 2004

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The results of previous studies conducted at the University of Hohenheim and the International Center for Agricultural Research in the Dry Areas (ICARDA) indicated that the yielding ability and stability of barley (Hordeum vulgare L.) could be improved in environments with drought stress by increasing the level of heterozygosity. This would require increasing the outbreeding rate of locally adapted breeding materials. As a first step, we estimated the outcrossing rate of 12 barley landraces (Hordeum vulgare ssp. vulgare, in short H. vulgare) and 13 sympatrically occurring populations of its wild progenitor [Hordeum vulgare ssp. spontaneum (C. Koch), in short H. spontaneum] collected from semi-arid localities in Jordan during the 1999/2000 growing season. In each H. vulgare or H. spontaneum population 28-48 spikes were sampled, and up to six offspring (seeds) per spike (called a family) were used for PCR analyses. Collection sites covered high-low transects for rainfall and altitude in order to detect possible environmental effects on the outcrossing rate. Four microsatellite markers located on different chromosomes were used to genotype the samples for estimating the outcrossing rate. Low season-specific multilocus outcrossing rates (tm) were found in both cultivated and wild barley, ranging among populations from 0-1.8% with a mean of 0.34%. Outcrossing rates based on inbreeding equilibrium (te), indicating outcrossing averaged across years, were two- to threefold higher than the season-specific estimates. Under high rainfall conditions somewhat higher--though not significantly higher--outcrossing rates were observed in H. spontaneum than in H. vulgare. The season-specific outcrossing rate in H. spontaneum was positively correlated (r = 0.67, P = 0.01) with average annual precipitation and negatively correlated (r = 0.59, P = 0.05) with monthly average temperature during flowering. The results suggest that outcrossing may vary considerably among seasons and that high precipitation and cool temperatures during flowering tend to enhance outcrossing. The rather low levels of outcrossing detected indicate that increased vigour due to heterozygosity has not been a major fitness advantage in the evolution and domestication of H. spontaneum and H. vulgare, respectively. Stable seed production to secure survival under extreme heat and drought stress may have been more important. Cleistogamy may be considered as an effective mechanism to warrant pollination even in drought-stunted plants with non-extruding spikes.

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Section: Influence Of Climatic Conditionssupporting

confidence: 93%

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

et al. 2004

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“…was negative in d l cases, which tends to support the earlier observation that low temperature promotes natural outcrossing in barley (Giles et al, 1974). However, this generalization cannot be made in the presence of field level moisture stress, as the rate of outcrossing at Davis, California was higher than for the dryland population at Saskatoon.…”

Section: Resultssupporting

confidence: 77%

Outcrossing Rates in Barley Populations in the Canadian Prairies

Chaudhary¹,

Jana²,

Acharya³

1980

Can. J. Genet. Cytol.

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Using three morphological markers, the magnitude of natural cross-fertilization in three successive generations, F,, P;, and F, of foul single crosses of barley (Hordeum vulgare L.) was estimated under dryland conditions of the Canadian Prairies. The average frequency of outcrossing was very low (0.35%). Somewhat higher rates of outcrossing were observed in a highly variable composite cross population of barley (CC XXI). CC XXI showed an overall outcrossing rate of 0.8096, when propagated under irrigated conditions, but only 0.47% under rainfed conditions. Outcrossing was significantly influenced by three eomponents of the environment: temperature, precipitation and relative humidity during the flowering period. Temperature was most important when moisture was not limiting, whereas precipitation wae the most important factor under field level drought. The overall frequency of outcrossing in CC XXI was not only considerably lower in the Prairies than in California or Scotland, but decreased progressively with advancing generations, in contrast to results in California.Au moyen de trois marqueurs morphologiques, on a pu estimer dans les conditions normales dts Prairies l'amplitude de l'exogamie naturelle dms trois ginirations successives (F,, F4 et %) chez quatre croisements simples d'orge (Hordeum vulgare L.). La friquence moyenne d'kxogamie s'est averke trks faible (0.35%). Des taux quelque peu plus ilevis furent obsemis dans une population croide t&s variable (CCXXI). Ainsi, la ligntk CCXXI affkkait un taux global d'ixogamie de 0.8Q8, sous irrigation, en regard de 0.47%, sans a p r t d'eau. L'ixoglarnie itait influencie de fason significative par trois composantes de I'environnement: la tempkrature, la precipitation et l'humidit6 relative au cours de la M o d e de floraison. La tern+rature ttait plus importante lorsque l'humidit6 n'6tait pas un facbur limitatif, alors que la prkcipitation s'avbait le facteur le plus important dans les conditions de s6cheresse. La Mquence globale d'ixogamie chez CCXXI n'itait pas searlement plus faible dans les Prairies qu'en Californie ou en Ecosse, mais dicroissait graduellement au fur et P mesure des generations, contrairement aux r&ultats obtenus en Cdifornie.[Traduit par le journal]

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“…vulgare) has many of the hallmarks known to be associated with a high level of LD. Its effective recombination rate is dramatically reduced by its predominantly inbreeding habit, with an estimated outcrossing rate of 5% in winter barley and ,0.5% in spring barley (Giles et al 1974;Doll 1987;Abdel-Ghani et al 2005). Domestication and intensive selection have introduced major bottlenecks in genetic variation, and these are thought to be largely responsible for the perceived narrowness of the modern gene pool (Badr et al 2000;Russell et al 2000;Matus and Hayes 2002).…”

mentioning

confidence: 99%

Effects of Introgression and Recombination on Haplotype Structure and Linkage Disequilibrium Surrounding a Locus EncodingBymovirusResistance in Barley

Stracke

Presterl²,

Stein

et al. 2007

Genetics

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We present a detailed analysis of linkage disequilibrium (LD) in the physical and genetic context of the barley gene Hv-eIF4E, which confers resistance to the barley yellow mosaic virus (BYMV) complex. Eightythree SNPs distributed over 132 kb of Hv-eIF4E and six additional fragments genetically mapped to its flanking region were used to derive haplotypes from 131 accessions. Three haplogroups were recognized, discriminating between the alleles rym4 and rym5, which each encode for a spectrum of resistance to BYMV. With increasing map distance, haplotypes of susceptible genotypes displayed diverse patterns driven mainly by recombination, whereas haplotype diversity within the subgroups of resistant genotypes was limited. We conclude that the breakdown of LD within 1 cM of the resistance gene was generated mainly by susceptible genotypes. Despite the LD decay, a significant association between haplotype and resistance to BYMV was detected up to a distance of 5.5 cM from the resistance gene. The LD pattern and the haplotype structure of the target chromosomal region are the result of interplay between low recombination and recent breeding history.T HE ever-increasing availability of nucleotide sequence, and the concomitant improvement that this brings to our understanding of the organization of complex crop plant genomes, has created the opportunity to identify trait-related genes and to analyze their allelic diversity. The association between phenotype and genotype in diverse populations represents a powerful approach, but the applicability and design of such analyses depend critically on the extent and pattern of linkage disequilibrium (LD) present in the study population. Cultivated barley (Hordeum vulgare ssp. vulgare) has many of the hallmarks known to be associated with a high level of LD. Its effective recombination rate is dramatically reduced by its predominantly inbreeding habit, with an estimated outcrossing rate of 5% in winter barley and ,0.5% in spring barley (Giles et al. 1974;Doll 1987;Abdel-Ghani et al. 2005). Domestication and intensive selection have introduced major bottlenecks in genetic variation, and these are thought to be largely responsible for the perceived narrowness of the modern gene pool (Badr et al. 2000;Russell et al. 2000;Matus and Hayes 2002). LD in modern spring barley, as estimated from a whole-genome survey, extends over distances of at least 10 cM, indicative of an extensive conservation of the genetic identity of barley chromosomes (Kraakman et al. 2004). However, estimates of genomewide LD conceal localized variation, which, as has been shown for a number of species, can be substantial and independent of the mating system (Gupta et al. 2005). In the self-pollinating species Arabidopsis thaliana LD varies from ,10 kb in global (Tian et al. 2002) to 50-250 kb in local populations (Nordborg et al. , 2005Aranzana et al. 2005). Within a given set of maize (an outbreeding species) accessions, the extent of LD has been documented to vary widely around different genes and chr...

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The frequency of natural cross-fertilization in a composite cross of barley grown in Scotland

Cited by 5 publications

References 4 publications

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

Outcrossing Rates in Barley Populations in the Canadian Prairies

Effects of Introgression and Recombination on Haplotype Structure and Linkage Disequilibrium Surrounding a Locus EncodingBymovirusResistance in Barley

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