Scientists Pinpoint Gene that Keeps Plant Cells 'In Touch'

Cell to cell communication is important in plant cells, especially during development. Plant cells communicate via microscopic channels embedded in their cell walls. These channels, called plasmodesmata, mediate the transport of metabolites and proteins. In meristems, or plant stem cells, plasmodesmata serve as the channels where genetic instructions for growth pass through. These microscopic pores are regulated by development and environmental signals. But little is known about the genes and molecular pathways that respond to these signals. Scientists at the Cold Spring Harbor Laboratory in New York, led by David Jackson, pinpointed the gene responsible for keeping plasmodesmata open.

Although restricting inter-cellular traffic can be beneficial at times, this can be detrimental to meristems. Environmental signals such as stress trigger the production of callose, a substance that blocks plasmodesmata. Oxygen free radicals can trigger the production of callose. The team identified a gene called Gat1 (gate-one) that encodes thioredoxin-m3, an enzyme that slows down and prevents the production of reactive oxygen species. Cells with defective Gat1 accumulate high levels of free radicals and other toxic ions. Seeds in which this gene failed to work were found by the scientists to give rise to seedlings that barely survived more than two weeks.

Jackson and colleagues also discovered that increasing the expression of Gat1 in mature leaves led to a delay in senescence and flowering. Controlling senescence may lead to the development of plants that last longer or flowers that stay fresh longer.

Read http://www.cshl.edu/public/releases/09_gat1.html for the complete article. The paper published by PNAS is available at http://www.pnas.org/content/early/2009/02/12/0808717106.full.pdf+html