Identifying genetic controls that keep plants from interbreeding with other species are the subject of a National Science Foundation Plant Genome research grant recently awarded to Colorado State University. The research project also includes an innovative program in which undergraduate honors biology students single out and identify tomato genes involved in these processes.
A research team headed by Colorado State biology professor Pat Bedinger has been awarded $3.9 million over four years to conduct a study — using tomato plants — of the highly evolved mechanisms flowering plants use for controlling mating. Bedinger’s research project centers on mechanisms that help avoid cross-species mating that could result in sterility or other problems. Often, these mechanisms entail specific molecular-level interactions between the pollen (male) and pistil (female), but just how a pistil knows to reject pollen from the wrong species is not well understood, Bedinger said.
"A plant does not have a whole lot of control over how it is pollinated," Bedinger said, noting the process of pollination typically employs wind or insects. "But plants have a distinct biochemical way to reject pollen from the wrong species."
Through a component of the project called "Many Minds," undergraduate students taking honors biology courses will play a key role in the research as they will spend four laboratory sessions identifying important genes and using online databases to analyze the genes.
"I love having individual undergraduate students in my lab," Bedinger said. "But involving all of the students in a laboratory section of a course in a research project is taking undergraduate participation to a new level. It is exciting for them to be working on a project without knowing what to expect for an outcome."
The project will also seek new information about pollination barriers in the tomato family by direct observation of cross-species pollinations. Bedinger will use both wild and domesticated tomato species. Wild tomato species – adapted for growth in harsh environments such as the Andes Mountains and Galapagos Islands – will not accept pollen from domestic tomatoes, while domestic tomatoes will accept the pollen of wild tomatoes.
Controlling plant reproduction can have major economic importance, Bedinger said, such as in the production of most hybrid crop plants. Bedinger’s research will further the understanding of regulating gene transfer between species of plants, such as transferring beneficial traits from wild to domesticated species and maintaining the genetic identity of wild species by preventing them from accepting interspecies pollen.
"If we can better understand these biochemical barriers, then we can better control them," Bedinger said.