The leaf economics spectrum of triploid and tetraploid C4 grass Miscanthus x giganteus

Authors: LI, SHUAI - University Of Illinois; MOLLER, CHRISTOPHER - University Of Illinois; MITCHELL, NOAH - University Of Illinois; MARTIN, DUNCAN - University Of Illinois; SACKS, ERIK - University Of Illinois; SAIKIA, SAMPURNA - University Of Illinois; LABONTE, NICHOLAS - University Of Illinois; BALDWIN, BRIAN - University Of Mississippi; MORRISON, JESSE - University Of Mississippi; FERGUSON, JOHN - University Of Cambridge; LEAKEY, ANDREW D B - University Of Illinois; Ainsworth, Elizabeth - Lisa

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2022
Publication Date: 9/20/2022
Citation: Li, S., Moller, C.A., Mitchell, N.G., Martin, D.G., Sacks, E.J., Saikia, S., Labonte, N.R., Baldwin, B.S., Morrison, J.I., Ferguson, J.N., Leakey, A., Ainsworth, E.A. 2022. The leaf economics spectrum of triploid and tetraploid C4 grass Miscanthus x giganteus. Plant Cell and Environment. 45(12):3462-3475. https://doi.org/10.1111/pce.14433.
DOI: https://doi.org/10.1111/pce.14433

Interpretive Summary: Fundamental leaf functional trait relationships are described in the leaf economics spectrum (LES), which encapsulates plant functional and ecological strategies. LES is largely based on C3 species from natural environments and has been studied rarely in C4 crops. Here, we show that C4 bioenergy crops occupy a distinct range of the LES, with greater photosynthetic rates and greater nitrogen use efficiency. Miscanthus x giganteus genotypes with different ploidy levels exhibit leaf trait divergence and distinct leaf functional relationships. By expanding the bivariate trait relationships described in the LES to include C4 crops in agricultural conditions, our study enhances understanding of overall worldwide patterns in leaf functional relationships and offers insight into the potential for ploidy to improve resource use efficiency.

Technical Abstract: The leaf economics spectrum (LES) describes multivariate correlations in leaf structural, physiological and chemical traits, originally based on diverse C3 species grown under natural ecosystems. However, the specific contribution of C4 species to the global LES is studied less widely. C4 species have a CO2 concentrating mechanism which drives high rates of photosynthesis and improves resource use efficiency, thus potentially pushing them towards the edge of the LES. Here, we measured foliage morphology, structure, photosynthesis, and nutrient content for hundreds of genotypes of the C4 grass Miscanthus×'giganteus grown in two common gardens over two seasons. We show substantial trait variations across M.×'giganteus genotypes and robust genotypic trait relationships. Compared to the global LES, M.×'giganteus genotypes had higher photosynthetic rates, lower stomatal conductance, and less nitrogen content, indicating greater water and photosynthetic nitrogen use efficiency in the C4 species. Additionally, tetraploid genotypes produced thicker leaves with greater leaf mass per area and lower leaf density than triploid genotypes. By expanding the LES relationships across C3 species to include C4 crops, these findings highlight that M.×'giganteus occupies the boundary of the global LES and suggest the potential for ploidy to alter LES traits.