New Phytol. 2022 Aug 12. doi: 10.1111/nph.18427. Online ahead of print.
ABSTRACT
Mesophyll CO2 conductance (gm ) in C3 species responds to short-term (minutes) changes in environment potentially due to changes in leaf anatomical and biochemical properties and measurement artifacts. Compared to C3 species, there is less information about gm responses to short-term changes in environmental conditions like pCO2 across diverse C4 species and the potential determinants of these responses. Using 16 C4 grasses we investigated the response of gm to short-term changes in pCO2 and its relationship with leaf anatomy and biochemistry. In general, gm increased as pCO2 decreased (statistically significant increase in 12 species), with percent increases in gm ranging from +13% to +250%. Greater increase in gm at low pCO2 was observed in species exhibiting relatively thinner mesophyll cell walls along with greater mesophyll surface area exposed to intercellular air spaces, leaf N, photosynthetic capacity and activities of phosphoenolpyruvate carboxylase and Rubisco. Species with greater CO2 response of gm were also able to maintain their leaf water-use efficiencies (TEi ) under low CO2 . Our study advances understanding about CO2 response of gm in diverse C4 species, identifies the key leaf traits related to this response and has implications for improving C4 photosynthetic models and TEi through modification of gm .
PMID:35959528 | DOI:10.1111/nph.18427
