It's believed that hundreds of microRNAs exist in each species of plant and animal, but the function of only a few is understood.

According to a new study by biologists at Rice University and the Whitehead Institute for Biomedical Research at the Massachusetts Institute of Technology, one of the first-discovered plant microRNAs -- known as miR164 -- plays a vital role in the proper development of the flowers, leaves, and stems of Arabidopsis.

"We know the miR164 gene is present in some other flowering plants and in rice, which is an indication that it's been conserved over more than 250 million years of evolution," said study co-author Bonnie Bartel, associate professor of biochemistry and cell biology at Rice. "Our study has found that this tiny strand of RNA is a crucial regulatory component of the molecular circuitry that controls basic organ development in the plant."

The study is featured on the cover of the June 22 issue of the journal Current Biology.

The research involved experiments on three strains of Arabidopsis: one normal, or wild-type strain, and two mutant strains created in the lab. In one of the mutants, miR164 was "overexpressed," or produced in far greater quantity than normal. The other mutant expressed an miR164 target gene that was resistant to regulation by miR164, allowing the researchers to observe the consequences of a loss of miR164 regulation.

Researchers found abnormal development of leaves and flowers in both mutants. When miR164 regulation of a target gene was absent, plants produced the wrong number of organs. For example, flowers tended to contain too many petals and too few sepals, the husk-like coverings that protect the flower during budding. Whe
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Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
21-Jun-2004