RT Journal Article
SR Electronic
T1 The legacy of C<sub>4</sub> evolution in the hydraulics of C<sub>3</sub> and C<sub>4</sub> grasses
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.05.14.097030
DO 10.1101/2020.05.14.097030
A1 Zhou, Haoran
A1 Akçay, Erol
A1 Edwards, Erika
A1 Helliker, Brent
YR 2021
UL http://biorxiv.org/content/early/2021/03/28/2020.05.14.097030.abstract
AB The anatomical reorganization required for optimal C4 photosynthesis should also impact plant hydraulics. Most C4 plants possess large bundle-sheath cells and high vein density, which should also lead to higher leaf hydraulic conductance (Kleaf) and capacitance. Paradoxically, the C4 pathway reduces water demand and increases water-use-efficiency, creating a potential mis-match between supply capacity and demand in C4 plant water relations. We use phylogenetic analyses, physiological measurements, and models to examine the reorganization of hydraulics in closely-related C4 and C3 grasses. Evolutionarily young C4 lineages have higher Kleaf, capacitance, turgor-loss-point, and lower stomatal conductance than their C3 relatives. In contrast, species from older C4 lineages show decreased Kleaf and capacitance, indicating that over time, C4 plants have evolved to optimize hydraulic investments while maintaining C4 anatomical requirements. The initial “over-plumbing” of C4 plants disrupts the positive correlation between maximal assimilation rate and Kleaf, decoupling a key relationship between hydraulics and photosynthesis generally observed in vascular plants.Competing Interest StatementThe authors have declared no competing interest.