Poster: Mineral nutrition

Abs # 192: Wood formation in poplar is affected by nitrogen availibity

Presenter:	Pitre, Frederic E., frederic.pitre@rsvs.ulaval.ca
Authors	Pitre, Frederic E. (A)   Cooke, Janice E.K. (A)   Davis, Mark  (B)   Davis, John M. (C)   MacKay, John J. (A)
Affiliations:	(A): Laval University (B): DOE, National Renewable Energy Lab (C): University of Florida

Nitrogen has a profound impact on the growth and development of plants. This is especially true for Populus species and their hybrids, which exhibit strong phenotypic plasticity in response to nitrogen availability. However, surprisingly little is known about how nitrogen availability affects wood properties. In this project, we are investigating the effects of nitrogen availability on formation in Populus trichocarpa x deltoides, at the cellular and molecular level. In planta nitrogen status was manipulated either through exogenous application of ammonium nitrate or by stem girdling. Microscopic investigations of stem tissues from high N-treated trees showed reduced lignin deposition relative to adequate or low N-treated trees. These observations were corroborated by quantitative biochemical analyses that revealed a measurably reduced lignin content in high N trees compared to low N trees. Analysis of gene expression associated with the lignin biosynthetic pathway indicated that the transcripts levels of certain genes involved in lignin biosynthesis are decreased in response to elevated nitrogen. These results suggest that partitioning of carbon resources into cell wall components – particularly lignin – is altered in response to nitrogen availability.