Mesophyll conductance response to short‐term changes in pCO2 is related to leaf anatomy and biochemistry in diverse C4 grasses. Issue 4 (1st September 2022)

• Record Type: Journal Article
• Authors: Pathare, Varsha S.; DiMario, Robert J.; Koteyeva, Nuria; Cousins, Asaph B.
• Is Part Of: New phytologist. Volume 236:Issue 4(2022)
• Page Start: 1281
• Page End: 1295
• Publication Date: 2022-09-01
• Subjects: C4 photosynthesis -- carbonic anhydrase (CA) -- CO2 response of mesophyll conductance -- leaf anatomy -- mesophyll cell wall thickness -- PEPC affinity for bicarbonate (Km) -- phosphoenolpyruvate carboxylase (PEPC) -- water‐use efficiency; Botany -- Periodicals; 580
• DOI: 10.1111/nph.18427
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Mesophyll CO2 conductance ( g m ) in C3 species responds to short‐term (minutes) changes in environment potentially due to changes in leaf anatomical and biochemical properties and measurement artefacts. Compared with C3 species, there is less information on g m responses to short‐term changes in environmental conditions such as partial pressure of CO2 ( p CO2 ) across diverse C4 species and the potential determinants of these responses. Using 16 C4 grasses we investigated the response of g m to short‐term changes in p CO2 and its relationship with leaf anatomy and biochemistry. In general, g m increased as p CO2 decreased (statistically significant increase in 12 species), with percentage increases in g m ranging from +13% to +250%. Greater increase in g m at low p CO2 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 responses of g m were also able to maintain their leaf water‐use efficiencies (TEi ) under low CO2 . Our study advances understanding of CO2 response of g m 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 g m .