Importance of diversity in plant breeding
Crop improvement is predicated on identifying new alleles and introgressing them into breeding lines, particularly in those crops that have low levels of genetic diversity. Shuffling alleles by crossing among very genetically similar lines cannot produce continued improvements over the long term.
Many disease resistance genes now in our current cultivars were introgressed from wild relatives. For example, most cultivated tomato varieties contain nematode resistance genes crossed in from wild relatives of tomato.
, a wild relative of tomato that has been used as a source of disease resistance genes.