Some of the most well established patterns in ecosystem science are correlations between plant chemistry and ecological processes like decomposition, resource allocation, and herbivory. For example, lignin:N ratios in leaf litter are often correlated with decomposition rate, yet the chemical mechanisms underlying this relationship are not well understood. Today, advances in plant genetics have led to the production of Arabidopsis thaliana mutants that vary in either lignin content or in specific aspects of lignin chemical composition (e.g. ratios of syringyl:guaiacyl units and cinnamyl alcohol:cinnamylaldehyde units). If these mutants vary only in this single litter chemistry parameter, use of these plants in decomposition experiments would allow us to determine the independent effects of lignin content and chemistry on decomposition rate without relying on correlative traits. We selected eight mutants plus a wild type and analyzed total carbon content, total nitrogen content, and cell wall composition of stem material to determine the whether plants tissue chemistry traits co-varied within a plant type. In addition, plants were grown under three different levels of N availability to establish N treatment effects on variations in tissue chemistry.
Cellulose content, soluble sugar content, nitrogen content, and carbon content were not significantly different between mutants and wild type plants (P > 0.05). Furthermore, these chemistry parameters were not significantly altered by N treatment (P > 0.05). However, C:N ratios of stem tissue from plants grown under low N availability (40 ppm) was significantly higher than plants grown under moderate N availability (140 ppm; P < 0.0001), which was higher than plants grown under high N availability (240 ppm; P < 0.0001). Our results indicate that these eight Arabidopsis mutants vary in single tissue quality parameters independently from other plant chemistry traits. Furthermore, N availability affects N accumulation, but not C accumulation, in both modified and wild type Arabidopsis. Use of these plants in decomposition studies will allow us to directly test long-standing hypotheses about the independent effects of lignin and nitrogen on decomposition rate and lead to potentially important advances in process-based models of decomposition.