The release of genetically modified grasses. Part 1: pollen dispersal to traps in Lolium perenne

Giddings, G. D.; Hamilton, N. Ruaraidh Sackville; Hayward, M. D.

doi:10.1007/s001220050507

Cited by 52 publications

(36 citation statements)

References 10 publications

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“…Using this function the sum of squared differences between observed and expected values of all 430 potential mating pairs was 1575. This value indicated a 51.0% better fit than the random mating model, a 44.7% better fit than the model based on the data of Giddings et al (1997a), a 28.4% better fit than the inverse distance function and a 9.5% better fit than the inverse third power distance function. When the flowering characteristics were included in the calculation of expected values, the fit of the inverse quadratic function slightly improved (Figure 3b), as the sum of squared differences reduced to 1563 (0.77%).…”

Section: Relationship Between Paternity and Field Datamentioning

confidence: 83%

“…To determine expected values, proximity data and the recorded field data on flowering were used. First, published data on pollen deposition rates in relation to distance were examined (Giddings et al, 1997a), which revealed a perfect linear relationship between the inverse of pollen deposition and inter-plant distance (Figure 2). This relationship was used to estimate the relative contribution of each potential pollen donor to the pollen cloud around each of the 49 mother plants as a function of spatial arrangement, with the exception that an arbitrary minor pollen contribution by the mother plant was assumed.…”

Section: Selection Of Progeniesmentioning

confidence: 99%

“…The effect of inter-plant distance on pollen deposition rates between pairs of plants was estimated by several functions, including the one derived from the data of Giddings et al (1997a) that was used in the selection of progenies, and functions assuming an exponential reduction in pollen deposition rates with increasing interplant distance. These functions were used to estimate the relative contributions of potential pollen donors to the progenies of analysed mother plants, assuming that pollination rates were a function of distance only.…”

Section: Paternity In Relation To Field Datamentioning

confidence: 99%

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Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass

2006

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SummaryGenebank accessions stored as seed populations require periodic rejuvenation in order to maintain sufficient numbers of viable seeds. During rejuvenation the genetic composition of accessions may be altered for a variety of reasons, of which variation in pollination rates between plants is the least understood. In the present study, a paternity exclusion analysis was performed on a rejuvenated accession of perennial ryegrass. In addition, flowering data of the 49 parental plants were collected during the flowering season. The aim of the study was to determine how accurate variation in pollination rates between plants can be predicted from data on the spatial and temporal distribution of pollen release. The parental population and a total of 551 offspring from 12 progeny arrays were genotyped by means of molecular analysis. Using 25 microsatellites, paternity was identified for 81.9% of the offspring, while remaining ambiguities were resolved by AFLP analysis, except in four cases. Within the total sample 9 cases of contamination were observed. Mating within the study population was clearly non-random, as 61.9% of the identified pollen donors were located within 1 m distance from the mother plant. Observed pollination rates were very well described by an inverse quadratic function of inter-plant distance between potential mating pairs. Incorporation of the recorded flowering data in the calculation of expected pollination rates improved the goodness of fit with observed values by only 0.77%. Suggestions to reduce the variance in paternal contributions were presented. However, contamination was considered more threatening to the genetic integrity of perennial ryegrass germplasm than variation in pollination rates between plants, and indicated the need for improved measures to avoid gene flow from other germplasm.

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Section: Relationship Between Paternity and Field Datamentioning

confidence: 83%

Section: Selection Of Progeniesmentioning

confidence: 99%

Section: Paternity In Relation To Field Datamentioning

confidence: 99%

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Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass

2006

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“…Wind-dispersed pollen has a leptokurtic dispersal distribution from point sources (4-7), and, therefore, the proportion of fertilized ovules and seed set in recipient plants decreases rapidly with distance from the pollen donor (8). Wind direction, speed, turbulence, and gravity also affect pollen deposition (9)(10)(11). The key to pollen availability is density of donor plants, again studied almost exclusively in animalpollinated systems (12)(13)(14)(15)(16)(17)(18).…”

mentioning

confidence: 99%

Pollen limitation causes an Allee effect in a wind-pollinated invasive grass ( Spartina alterniflora )

Davis

Taylor

Lambrinos

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

187

155

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It is usually assumed that pollen availability does not limit reproduction in wind-pollinated plants. Little evidence either supporting or contradicting this assumption exists, despite the importance of seed production to population persistence and growth. We investigated the role of pollen limitation in an invasive estuarine grass (Spartina alterniflora), with a manipulative pollen supplementation and exclusion experiment in areas of high population density and at the low-density leading edge of the invasion. We also quantified pollen deposition rates on stigmas and pollen traps along a windward to leeward gradient. We found pollen impoverishment at the low-density leading edge of a large invasion, causing an 8-fold reduction in seed set. We found 9-fold more pollen on stigmas of high-density plants than on those of lowdensity plants. Pollen deposition rates on stigmas and traps did not increase downwind of low-density plants but did increase downwind of high-density plants and dropped off precipitously across a gap that lacked pollen donors. The delay of appreciable numbers of seed caused by pollen limitation persists for decades until vegetative growth coalesces plants into continuous meadows, and this Allee effect has slowed the rate of spread of the invasion.

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“…Significant pollen flow from Lolium perenne plots has been recorded by Giddings et al (1997), and developed into a landscape gene flow model by Giddings (2000). While this latter model did not incorporate the measurement of actual gene flow patterns as evidenced by pollination/hybridization events, this more precise kind of data has been generated in a landscape-level experiment on gene flow from a herbicide tolerant Agrostis stolonifera cultivar plot in the United States (Watrud et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Tracing field hybridization in Ryegrass species using microsatellite and morphological markers

Ryan

Mullins

Burke

et al. 2006

Environ. Biosafety Res.

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We have assessed the utility of morphological and microsatellite markers for tracing field hybridization between Lolium multiflorum and Lolium perenne in cereal-enclosed gene flow plots. The presence of awns on the inflorescence of F 1 hybrids was found to be a reliable, but underscoring, indicator of L. multiflorum paternity in L. perenne derived seed as determined by inheritance of species-specific alleles at the microsatellite locus 'H01 H06' in these progeny. A positive correlation was evident in the experimental treatment between the number of pollen donor plants in a given plot and the frequency of hybrid F 1 seed harvested from pollen receptor plants in that plot. These experiments have established the utility of naturally occurring heritable markers for the measurement of gene flow rates in field Ryegrass populations, with particular significance for risk assessment modeling of potential gene flow from transgenic grass cultivars.

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The release of genetically modified grasses. Part 1: pollen dispersal to traps in Lolium perenne

Cited by 52 publications

References 10 publications

Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass

Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass

Pollen limitation causes an Allee effect in a wind-pollinated invasive grass ( Spartina alterniflora )

Tracing field hybridization in Ryegrass species using microsatellite and morphological markers

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