Term	Definition
Gap analysis	A method to evaluate the representation of biodiversity in conservation repositories such as genebanks. This approach assists in prioritizing efforts to collect and conserve biodiversity by identifying species that are underrepresented in genebanks collections (in situ conservation) or geographic regions that were not thoroughly sampled (ex situ analysis). Gap analysis is mainly conducted for crop wild relatives due to their applied importance.
Linkage disequilibrium	Association between alleles at two or more loci leading to higher frequency of dependence in segregation. Linkage disequilibrium is pronounced in elite domesticated germplasm but is also observed in natural wild populations due to demographic and selective constraints. The level of LD determines the resolution of mapping trait of interest in a segregating population or diversity panel.
Introgression	Transmission of genetic variation between individuals. Introgression relies on the crossing potential between the two individuals and also on the recombination landscape around the target genomic region.
Genetic drag	The negative effects of linked genetic variation to the trait of interest. Introgression of genetic variation from one source (e.g., crop wild relative) into a recipient variety involves a crossing step followed by consecutive backcrossing steps to recruit back the recipient variety properties. Linkage disequilibrium between the targeted beneficial trait for introgression and a deleterious or unfavorable genetic variation may “drag” the negative component and reduce the fitness of the hybrid. Strong linkage between the beneficial and negative genetic variation will require much more effort to purge the “dragged” negative effect.
Environmental stressor	Any environmental factor that can have a negative impact on the plant fitness. The environmental stress can be abiotic like drought and heat or biotic like disease or competition with other organisms. In many cases, stressors are correlated (abiotic and biotic) and their impact on the plant fitness is complex, thus the underlying resistance or tolerance to stress may be a convolution of multiple mechanisms.