Inbreeding is generally deleterious, even in flowering plants. Since inbreeding raises the risk that bad copies of a gene will be expressed, inbred progeny suffer from reduced viability.
Many flowering plants are able to recognize and reject their own pollen, thereby preventing inbreeding despite the plants' hermaphroditic nature. This mechanism is a complex trait that involves the interaction of a gene that tags the pollen with an identifier molecule, and a gene that produces a molecule capable of detecting pollen produced by the same plant.
Evolutionary biologists have often argued that once complex traits are lost, they are seldom regained. But a new study, led by biologists at McGill University and published in the journal PLOS Biology, suggests that this may not be the case for self-pollen recognition.
In the evolutionary lineage leading to the genus Leavenworthia (a plant group related to canola and cole crops such as broccoli and cabbage), the ancestral genes that code for self-pollen recognition were lost. But the self-pollen recognition function in Leavenworthia appears to have been taken up by two other genes that originally may have had a different role -- for example, in pathogen recognition.
"Self-incompatibility," the pollen-recognition system that enables plants to avoid the inbreeding caused by self-pollination, involves a pair of tightly linked genes known as the S locus. In this study, the researchers analyzed the gene sequence, genome organization, and gene evolutionary history of S loci in members of the Brassicaceae family, which includes plants of the genus Leavenworthia.
"We conclude that both genes that comprise the ancestral S locus in the Brassicaceae were lost in Leavenworthia," says McGill researcher Sier-Ching Chantha, lead author of the study. Our analyses show, however, that plants of this genus have two other linked genes that exhibit patterns char
|Contact: Chris Chipello|