Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2005
Publication Date: 9/5/2005
Citation: Robinson, A.R., Gheneim, R., Kozak, R.A., Ellis, D.D., Mansfield, S.D. 2005. The potential of metabolite profiling as a selection tool for genotype discrimination in populus. Journal of Experimental Botany 56:2807-2819. Interpretive Summary: In crop improvement, the identification of individuals with traits of interest is critical. Often, however, the identification of these desired traits cannot be done until the plants are mature. In annual crops this is often not too much of a burden but in perennial crops, such as forest trees, this may take decades. Therefore, the development of systems to test for superior traits at an early age is crucial. This paper discusses the use of a technique known as metabolite profiling where a multitude of compounds are quantified in a plant (profiled) and then particular profiles of compounds can be correlated with particular traits. Here we were comparing the metabolite profiles of trees with enhanced pulping properties due to the genetic engineering of a gene conferring altered lignin. Carbohydrates as a metabolite group in plants proved useful in distinguishing the genetically engineered plants from non-engineered plants. These results validate the potential of using metabolite profiling techniques for marker generation to aid plant/tree breeding for industrial applications.
Technical Abstract: Differences between wild-type Populus tremula alba and two transgenic lines with modified lignin monomer composition, were interrogated using metabolic profiling. Analysis of metabolite abundance data by GC-MS, coupled with principal components analysis (PCA), successfully differentiated between lines that had distinct phenotypes, whether samples were taken from the cambial zone or non-lignifying suspension tissue cultures. Interestingly, the GC-MS analysis detected relatively few phenolic metabolites in cambial extracts, although a single metabolite associated with the differentiation between lines was directly related to the phenylpropanoid pathway or other down-stream aspects of lignin biosynthesis. In fact, carbohydrates, which have only an indirect relationship with the modified lignin monomer composition, featured strongly in the line-differentiating aspects of the statistical analysis. Traditional HPLC analysis was employed to verify these GC-MS data. These findings demonstrate that metabolic traits can be dissected reliably and accurately by metabolomic analyses, enabling the discrimination of individual genotypes of the same tree species that exhibit marked differences in industrially relevant wood traits. Furthermore, this validates the potential of using metabolite profiling techniques for marker generation in the context of plant/tree breeding for industrial applications.