Abstract
BackgroundIntrogressive hybridization can reassort genetic variants into beneficial combinations, permitting adaptation to new ecological niches. To evaluate evolutionary patterns and dynamics that contribute to introgression, we investigate six wild Vitis species that are native to the Southwestern United States and useful for breeding grapevine (V. vinifera) rootstocks.ResultsBy creating a reference genome assembly from one wild species, V. arizonica, and by resequencing 130 accessions, we focus on identifying putatively introgressed regions (pIRs) between species. We find six species pairs with signals of introgression between them, comprising up to ~ 8% of the extant genome for some pairs. The pIRs tend to be gene poor, located in regions of high recombination and enriched for genes implicated in disease resistance functions. To assess potential pIR function, we explore SNP associations to bioclimatic variables and to bacterial levels after infection with the causative agent of Pierce’s disease (Xylella fastidiosa). pIRs are enriched for SNPs associated with both climate and bacterial levels, suggesting that introgression is driven by adaptation to biotic and abiotic stressors.ConclusionsAltogether, this study yields insights into the genomic extent of introgression, potential pressures that shape adaptive introgression, and the evolutionary history of economically important wild relatives of a critical crop.
Highlights
Introgressive hybridization can reassort genetic variants into beneficial combinations, permitting adaptation to new ecological niches
Given that species are interfertile and can overlap substantively in geographic range, are they genetically distinct? Second, if they are distinct, is there genetic evidence for introgression? Third, if there is evidence for introgression, what are the genomic characteristics of introgressed regions, in terms of locations, size, and gene content? is there evidence that introgression events have played an adaptive role, as evidenced by genetic associations with either disease resistance or bioclimatic variables? In addressing these questions, this study provides novel insights into the evolutionary dynamics that shape the radiation of Vitis and identifies potentially useful genomic targets for breeding
The two metrics were significantly correlated (R > 0.75, p < 2.2e−16) along the genome (Additional File 2: Figure S12) and gave qualitatively similar results; we focused on fdM because positive values are interpretable as exchange of derived alleles between P2 and P3 [41]
Summary
Introgressive hybridization can reassort genetic variants into beneficial combinations, permitting adaptation to new ecological niches. There is growing evidence, that introgressive hybridization between populations and species does more than homogenize gene pools It may be a source of novelty that reassorts genetic variants into beneficial combinations, Morales-Cruz et al Genome Biology (2021) 22:254 permitting adaptation to new ecological niches [3]. This ability to reassort genetic variation may partially explain the highly reticulated evolutionary history of adaptive radiations like Heliconius butterflies [4], tomatoes [5], Darwin’s finches [6], and African cichlids [7]. Introgression has played a major role in the diversification and speciation of angiosperms [8], because hybridization affects an estimated ~ 25% of flowering plant species [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
