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Abstract Detail

Population Genetics/Genomics

Hernandez, Fernando [1], Brunet, Johanne [2].

Introgression of cultivar genes into wild carrot populations.

The concern for the impact of gene transfer between cultivars and wild populations has increased with the advent of genetically modified crops. The development of gene editing technologies for crop modification only amplifies the criticality of this important issue. Wild and cultivated carrots belong to the same species (Daucus carota) and can hybridize, a process which may transfer cultivar genes into wild populations. Wild carrots are outcrossed, insect-pollinated, have spread to every state in the United States and have been declared invasive in many states. Hybrids between cultivated and wild carrots have been detected in wild populations, but the extent to which hybridization has led to permanent gene introgression is unclear and the subject of this study. We sampled 29 wild populations from seven states: California (CA), Colorado (CO), Iowa (IA), Massachusetts (MA), Minnesota (MN), South Dakota (SD), and Wisconsin (WI). Leaf tissue was collected from wild carrot populations and DNA extracted from 414 individuals, 10-20 per population. Genotyping by sequencing was performed on these samples. We also included previously genotyped samples: 144 cultivars from United States, Europe, and Asia and North Africa, five wild individuals from Europe and three from Asia, and one individual of D. syrticus, a closely related species. Using ADMIXTURE and principal component analysis on ~13K high quality SNPs, we detected two major genetic clusters, differentiating cultivated and wild samples (FST= 0.20). Within wilds, we observed two well differentiated genetic clusters (FST= 0.27), one cluster was represented by individuals from CO, the other by individuals from WI, MN, and IA while samples from CA, MA and SD indicated admixture. To test for significant cultivar to wild introgression, we used Patterson ´s D statistics (ABBA-BABA tests) and TreeMix, using D. syrticus as an outgroup. We detected consistent patterns of introgression (up to 20% of the genome) in populations from MA, CO and two (out of five) populations from CA, showing that cultivar alleles have introgressed into wild carrots. Surprisingly, we found no evidence of introgression in populations from WI, some of which were collected near a carrot breeding site, where gene flow is expected. Differences in ecological factors, including winter temperatures, may be limiting the spread of cultivar genes in some states. We will discuss whether some regions of the genome are more (or less) prone to introgression and whether introgression is explained by multiple independent introgression events or a few events that have spread among wild populations.

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Related Links:
Gene flow, population genetic structure and introgression of cultivar genes in carrot
Brunet lab website
Fernando Hernandez Website
Fernando Hernandez on Research Gate

1 - National University of the South , Agronomy , Sede Rectorado: Avenida Colón 80, Bahía Blanca , Buenos Aires , 8000FTN, Argentina
2 - USDA- Agricultural Research Service , Vegetable Crops Research Unit , 455 Science Drive, Suite 170, Madison, WI, 53711, US

Daucus carota
gene flow
Gene editing

Presentation Type: Oral Paper
Session: PGG3, Population Genetics and Genomics III
Location: /
Date: Wednesday, July 21st, 2021
Time: 1:15 PM(EDT)
Number: PGG3004
Abstract ID:384
Candidate for Awards:Margaret Menzel Award

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