A Chosen Few
Part of this can be explained by the fact that citrus, which is native to Southeast Asia, hybridizes readily.
“Citrus has been domesticated and selected for millennia,?says Krueger, “so it’s possible that no early ancestors have escaped modification by humankind. But it’s worth investing in the plant exploration needed to find out.?/p>
Because citrus readily crosses and the resulting plants can be propagated true-to-type through grafting, selective breeding efforts encouraging desirable qualities—like sweetness—have been very successful. But breeding for certain traits can mean others are inadvertently lost.
“Selective breeding has led to advancement of certain ‘elite?germplasm lines,?says Krueger, “often at the expense of wild, ancestral types.?/p>
This doesn’t mean that new citrus types won’t be developed through conventional breeding and biotechnological breeding efforts. “But citrus breeding efforts probably won’t receive new genetic material from the area of origin because of the threat of habitat loss and the political challenges surrounding international exchange of plant materials.?/p>
Citrus In Situ
In situ preservation—conserving plants and organisms in their indigenous habitats—offers research opportunities available nowhere else. Like outdoor laboratories, citrus preserves allow the timeless interplay between citrus plants and their pesky pests and pathogens to carry on untouched—providing scientists with important glimpses into the plants?finely tuned, natural defenses.
“But germplasm maintained in this manner is more vulnerable to natural disasters and other events that could destroy valuable genes,?Krueger says.
This makes “ex situ?collections, like the Riverside citrus genebank, particularly critical—especially since many of the world’s wild citrus stands are at risk from encroaching industrial