WEST LAFAYETTE, Ind. - Purdue University researchers have determined aprocess that regulates activity of genes that control seed germinationand seedling development.
Mike Hasegawa, the Bruno C. Moser Distinguished Professor ofHorticulture and Landscape Architecture, and Kenji Miura, a formerPurdue postdoctoral researcher and now an assistant professor at TsukubaUniversity in Japan, discovered the step involved in keeping seeds fromgerminating in adverse conditions such as freezing temperatures ordrought, a factor in the survival of plant species.
The work, which was published Wednesday (March 11) in the early onlineversion of the Proceedings of the National Academy of Sciences, is partof ongoing research that has uncovered that similar processes affects aplant's freeze tolerance and absorption of phosphate.
"We've found the process, called sumoylation, is involved in theregulation of some major agricultural traits," Hasegawa said. "It isfundamental, basic research like this that allows us to understand howplants respond to hormones and environmental conditions."
Seeds produce a hormone called abscisic acid, or ABA, that preventsgermination. When environmental factors such as temperature are notoptimal for seed germination, ABA levels are high, which causesproduction of higher levels of a protein called ABI5. When the ABI5protein is active, it switches on genes that prevent germination.
Hasegawa's research showed that when a SUMO peptide is attached to theABI5 protein, the protein becomes inactive, switching off the genes thatprevent germination and seedling development.
"A single stimulus such as ABA affects transcription factors, which aremajor controllers of genes involved in complex processes such as seedgermination," Hasegawa said. "Sumoylation seems to be an importantprocess in the control of significant plant characteristics."
Hasegawa said that the ABI5 protein can become active again, haltinggermination and seedling development if condition are no longer optimal.When conditions change to make plant development possible, the proteincan once again be deactivated.
The National Science Foundation and the U.S. Department of Agriculturehave funded the research in Hasegawa's laboratory. Hasegawa's next stepis to determine how the sumoylation process leads to gene suppressionand expression.
Source: Purdue University
Mike Hasegawa discovered a process that regulates the genes in seeds that control germination and seedling development. When a peptide is attached to a particular protein in the seed, a process can begin that turns off the genes that are prohibiting germination.
(Photo Credit: (Purdue Agricultural Communications photo/Tom Campbell))