The Evolutionary Origin of C Photosynthesis in the Grass Subtribe Neurachninae.

The Australian grass subtribe Neurachninae contains closely related species that use C, C, and C photosynthesis. To gain insight into the evolution of C photosynthesis in grasses, we examined leaf gas exchange, anatomy and ultrastructure, and tissue localization of Gly decarboxylase subunit P (GLDP) in nine Neurachninae species. We identified previously unrecognized variation in leaf structure and physiology within that represents varying degrees of C-C intermediacy in the Neurachninae.

Evolutionary implications of C3 -C4 intermediates in the grass Alloteropsis semialata.

C4 photosynthesis is a complex trait resulting from a series of anatomical and biochemical modifications to the ancestral C3 pathway. It is thought to evolve in a stepwise manner, creating intermediates with different combinations of C4 -like components. Determining the adaptive value of these components is key to understanding how C4 photosynthesis can gradually assemble through natural selection.

Multiple photosynthetic transitions, polyploidy, and lateral gene transfer in the grass subtribe Neurachninae.

The Neurachninae is the only grass lineage known to contain C(3), C(4), and C(3)-C(4) intermediate species, and as such has been suggested as a model system for studies of photosynthetic pathway evolution in the Poaceae; however, a lack of a robust phylogenetic framework has hindered this possibility. In this study, plastid and nuclear markers were used to reconstruct evolutionary relationships among Neurachninae species. In addition, photosynthetic types were determined with carbon isotope ratios, and genome sizes with flow cytometry.