( Clintock--to 'tag' the ramosa1 gene. Th...)$6.5 Million Grant for Microarray Center at Yale School of Medicine

"As corn was being domesticated, farmers selected a larger and larger ear with more and more rows of kernels, based on the activity of genes other than ramosa1. But we suspect that as the ear got larger, it needed special alleles of ramosa1 to prevent the extra rows from forming branches instead of kernels," says Martienssen. "There may have been other reasons for selecting an unbranched ear, including the interaction with other genes that were subsequently lost during domestication, but we don't yet know if this is the case."

The study reveals that plants with more ramosa1 activity (e.g. typical corn) tend to have fewer branches, shorter branches, and fewer flowers whereas plants with less ramosa1 activity (e.g. sorghum, rice, and the ramosa corn variety described above) tend to have more branches, longer branches, and more flowers.

"We also looked at a popular ornamental grass that grows outside my office and found the same result. It has a spiky top like corn, so we were delighted to find that they have similar profiles of ramosa1 activity," says Martienssen.