Capturing genetic variation in crop wild relatives: An evolutionary approach

Abstract

Crop wild relatives (CWRs) offer novel genetic resources for crop improvement. To assist in the urgent need to collect and conserve CWR germplasm, we advance here the concept of an “evolutionary” approach. Central to this approach is the predictive use of spatial proxies of evolutionary processes (natural selection, gene flow and genetic drift) to locate and capture genetic variation. As a means to help validate this concept, we screened wild‐collected genotypes of woodland strawberry (Fragaria vesca) in a common garden. A quantitative genetic approach was then used to test the ability of two such proxies—mesoclimatic variation (a proxy of natural selection) and landscape isolation and geographic distance between populations (proxies of gene flow potential)—to predict spatial genetic variation in three quantitative traits (plant size, early season flower number and flower frost tolerance). Our results indicated a significant but variable effect of mesoclimatic conditions in structuring genetic variation in the wild, in addition to other undetermined regional scale processes. As a proxy of gene flow potential, landscape isolation was also a likely determinant of observed patterns—as opposed to, and regardless of, geographic distance between populations. We conclude that harnessing proxies of adaptive and nonadaptive evolutionary processes could provide a robust and valuable means to identify genetic variation in CWRs. We thus advocate wider use and development of this approach amongst researchers, breeders and practitioners, to expedite the capture and in situ conservation of genetic resources provided by crop wild relatives.

Genetic variation in herbivore resistance within a strawberry crop wild relative (Fragaria vesca L.)

“…Theory suggests that relatively high genetic variation can be found even in small geographic 321 areas (Thompson 2013; Egan et al 2018). Concordantly, we found significant genetic variation 322 in the measured resistance traits against the Northern European pest insect Galerucella tenella in 323 our screening of wild woodland strawberry, Fragaria vesca.…”

“…As per previous quantitative genetic analyses in F. vesca (Egan et al 2018), this model structure -in which genotype is fitted as a random effect -permitted environmental (withingenotype) variation to be partitioned from genetic (between-genotype) variation (Hill 2010) in order to predict a 'total genetic value' for each genotype (Piepho et al 2008). These values were used to visualize genetic variation in plots, or as an input to additional analyses, as detailed below.…”

Plant resistance does not compromise parasitoid-based biocontrol of a strawberry pest

“…The 16 plant genotypes used in this study were derived from distinct wild populations in Uppsala County, Sweden, during spring 2012 24,25,49 (Supplementary Material Table 1). The entire collection consists of 86 plant genotypes that have been screened for resistance against the strawberry leaf beetle 25 .…”

“…In this study we focused on wild woodland strawberry (Fragaria vesca L.), a promising resource for anti-herbivore resistance which can contribute to breeding programs for the commercially cultivated garden strawberry (F. x ananassa) [22][23][24][25] . Previously, we found very high intraspecific variation in plant resistance against the strawberry leaf beetle (Galerucella tenella L., Coleoptera: Chrysomelidae) among wild woodland strawberry genotypes 25 .…”

Genetic variation in herbivore resistance within a strawberry crop wild relative (Fragaria vesca L.)

“…Genetic resources for resistance against pests are limited within current strawberry cultivars and breeding programs (Liston et al 2014;Chen et al 2015). A good source to enhance traits for pest resistance is the naturally existing variation among the crop wild relatives (CWR) of cultivated strawberries (Egan et al 2018). Known as 'rewilding' or 'inverse breeding,' beneficial traits such as plant resistance to herbivores can be restored in future varieties by including CWR germplasm in breeding programs (Broekgaarden et al 2011;Andersen et al 2015;Dempewolf et al 2017).…”