BY LISA TREI
Recent research in the lab of Biological Sciences Professor Sharon Long, a Howard Hughes Medical Institute investigator, has identified new genes that appear to help guide beneficial bacteria during their invasion of plant hosts. Long says that these new findings, part of her research into how plants and bacteria communicate with one another, will help to advance efforts to find alternatives to nitrogen fertilizer used in improving crop yields.
"In the next decades, one of the biggest challenges for science will be to provide the knowledge that helps us to feed our fellow human beings, and to spare the limited resources that our earth can offer," Long says.
Long presented her findings at the annual meeting of The American Association for the Advancement of Science (AAAS) in Anaheim, Calif., on Saturday, Jan. 23. Her talk was titled, "Signal Exchange and Signal Transduction in Plant-Bacteria Symbiosis" or "The Underground Chemical Language of Bacteria and Plants."
During her 17 years at Stanford, Long has explored the symbiotic relationship between grains and bacteria, most notably how the legume family and Rhizobium bacteria exchange chemical signals. Legumes, such as alfalfa and peas, that establish an association with such bacteria are able to grow and synthesize adequate protein without added nitrogen fertilizer. Long says that an important goal is to improve agricultural yields, while sparing the limited resources of the Earth. Her research also has led to new insights into basic mechanisms of cell behavior, which may be applicable to other organisms.
In her work, Long has investigated how these specific bacteria and plants recognize one another, in the dark and underground, in the absence of the nervous system that allows animals to recognize each other. The partnership is quite specific out of the hundreds of families of flowering plants and thousands of bacteria in the soil, only leguminous plants and the Rhizobium bacteria form symbioses exclusively with each other. Long's research has tried to find out how these partners cause such profound changes in each other's growth and behavior.
By studying signals and signal transduction, Long says, it is possible to uncover new mechanisms that cells use to make decisions, for example, when to divide, and when to change growth or shape. Such behaviors are important for cells of all organisms, and the mechanisms that process external chemical signals to internal cell divisions may be broadly shared by living things. Long's research shows that the Rhizobium-legume system, which is accessible to both genetic and molecular study, provides an important opportunity to study signal exchange in development.
In the short term, Long says, it is
satisfying to know of the many possible applications of her new
work to plants. "The knowledge that emerges from these studies is
quite practical," she says. "The symbiosis has profoundly important
uses in sustainable agriculture and in agriculture in stressed
habitats [with] poor soil." SR