Lignin breakthroughs serve as GPS for plant research

Two articles published March 11 in The Plant Cell offer a step-by-step approach for studying plant traits, drawing on comprehensive, quantitative research on lignin formation in black cottonwood. Lignin, an important and complex polymer responsible for plant growth and development, provides mechanical strength and water transport that enables some trees to grow 100 meters tall. However, lignin must be removed for biofuel, pulp and paper production-a process that involves harsh chemicals and expensive treatments.

The research provides a new approach integrating knowledge of genes, proteins, plant chemical compounds and engineering modeling to understand how plants make products and structures needed for growth and development. This work in the new area of plant systems biology, integrating biology, chemistry and engineering, sets a new standard for understanding any complex biological feature in the future.

"I describe these findings as MapQuest for plant scientists," says Vincent Chiang, co-director of NC State's Forest Biotechnology Group, the lead team for the project, which involved scientists in the College of Natural Resources, College of Engineering and College of Sciences. "For example, the systems biology approach could be applied in research to develop sweeter citrus fruit, disease-resistant rice or drought-resistant trees."

Over many years of intensive research, the interdisciplinary team led by Chiang purified 21 pathway enzymes and analyzed 189 different parameters related to lignin formation. With help from engineering colleagues Cranos Williams and Joel Ducoste, the team developed models that predict how pathway enzymes affect lignin content and composition. One of the enzymes forms a novel four-part structure, which was discovered as part of this work, including quantitation of all 21 enzymes carried out by chemist David Muddiman.

"The model, based on a comprehensive set of equations for each step in the process, can now predict changes in the amount and composition of lignin, as well as why it's often difficult to modify lignin in plants" says Ronald Sederoff, co-director of Forest Biotechnology Group.

The GPS-like findings could reduce years of research time required to make future advances, Chiang says. "We hope that this research will stimulate similar work by young scientists. Don't be discouraged by complex biological processes. Our work shows a successful approach for such studies."

The research team includes former graduate students Jack Wang and Hsi-Chuan Chen, funded by the Jordan Endowment Scholarship at NC State. National Science Foundation Plant Genome Research Program Grant (DBI-0922391) supported graduate students Jina Song and Punith Naik from the College of Engineering; Ying-Chung Lin, Chien-Yuan Lin and Sermsawat Tunlaya-Anukit from the College of Natural Resources; Christopher Shuford and Angelito Nepomuceno from the College of Sciences; and undergraduate students, postdocs and faculty at NC State.