Articles
Gene flow and introgression of cultivar alleles in wild carrot populations at increasing distances from a source
Article number
1393_39
Pages
305 – 312
Language
English
Abstract
Introgression of cultivar alleles into wild populations could increase their invasiveness, and reduce their genetic diversity.
Cultivated and wild carrot belong to the same plant species, flower synchronously, are highly outcrossed, share pollinators, and are thus likely to hybridize when grown in proximity.
A large-scale study spanning 7 states and 29 wild populations detected introgression in some regions, but not in Wisconsin, despite the presence of a long-term breeding site and indirect evidence of gene flow in wild populations near the breeding site.
In the current study, we directly examine whether cultivar alleles can spread at increasing distances from the breeding site.
To reach this goal, we sampled leaf tissue from 10 individuals per population, every 300 m up to 1500 m, over three separate transects.
The sampling started from populations located at close proximity to the breeding site (near populations) (<500 m), and incorporated populations that were at significant distances (3.3-20.8 km) from the breeding site, and away from cultivated carrots (far populations). To permit detection of gene flow and introgression from cultivars, we included samples from the major breeding stocks that had been used at the breeding site over the past 40-plus years.
We extracted DNA from leaf tissue, performed genotyping by sequencing (GBS), and isolated single nucleotide polymorphisms (SNP). We ran admixture tests to identify hybrid and backcross individuals.
A low degree of admixture eliminated the need for further introgression tests.
We also examined whether the proximity to crop altered the genetic diversity of recipient populations and their genetic divergence with crop (FST). The results support the lack of introgression of cultivar alleles in these wild carrot populations.
We hypothesized the harsh Wisconsin winters may prevent the persistence of admixed individuals in these wild carrot populations.
Cultivated and wild carrot belong to the same plant species, flower synchronously, are highly outcrossed, share pollinators, and are thus likely to hybridize when grown in proximity.
A large-scale study spanning 7 states and 29 wild populations detected introgression in some regions, but not in Wisconsin, despite the presence of a long-term breeding site and indirect evidence of gene flow in wild populations near the breeding site.
In the current study, we directly examine whether cultivar alleles can spread at increasing distances from the breeding site.
To reach this goal, we sampled leaf tissue from 10 individuals per population, every 300 m up to 1500 m, over three separate transects.
The sampling started from populations located at close proximity to the breeding site (near populations) (<500 m), and incorporated populations that were at significant distances (3.3-20.8 km) from the breeding site, and away from cultivated carrots (far populations). To permit detection of gene flow and introgression from cultivars, we included samples from the major breeding stocks that had been used at the breeding site over the past 40-plus years.
We extracted DNA from leaf tissue, performed genotyping by sequencing (GBS), and isolated single nucleotide polymorphisms (SNP). We ran admixture tests to identify hybrid and backcross individuals.
A low degree of admixture eliminated the need for further introgression tests.
We also examined whether the proximity to crop altered the genetic diversity of recipient populations and their genetic divergence with crop (FST). The results support the lack of introgression of cultivar alleles in these wild carrot populations.
We hypothesized the harsh Wisconsin winters may prevent the persistence of admixed individuals in these wild carrot populations.
Authors
J. Brunet, F. Hernández, L. Palmieri
Keywords
admixture, Daucus carota, genetic divergence, genetic diversity, genotyping by sequencing, hybridization
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