ORCID Profile
0000-0002-5056-6868
Current Organisation
Washington State University
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Publisher: MDPI AG
Date: 20-07-2022
Abstract: In recent years, researchers have attempted to improve photosynthesis by introducing components from cyanobacterial and algal CO2-concentrating mechanisms (CCMs) into terrestrial C3 plants. For these attempts to succeed, we need to understand the CCM components in more detail, especially carbonic anhydrase (CA) and bicarbonate (HCO3−) transporters. Heterologous complementation systems capable of detecting carbonic anhydrase activity (i.e., catalysis of the pH-dependent interconversion between CO2 and HCO3−) or active HCO3− transport can be of great value in the process of introducing CCM components into terrestrial C3 plants. In this study, we generated a Saccharomyces cerevisiae CA knock-out (ΔNCE103 or ΔCA) that has a high-CO2-dependent phenotype (5% (v/v) CO2 in air). CAs produce HCO3− for anaplerotic pathways in S. cerevisiae therefore, the unavailability of HCO3− for neutral lipid biosynthesis is a limitation for the growth of ΔCA in ambient levels of CO2 (0.04% (v/v) CO2 in air). ΔCA can be complemented for growth at ambient levels of CO2 by expressing a CA from human red blood cells. ΔCA was also successfully complemented for growth at ambient levels of CO2 through the expression of CAs from Chlamydomonas reinhardtii and Arabidopsis thaliana. The ΔCA strain is also useful for investigating the activity of modified CAs, allowing for quick screening of modified CAs before putting them into the plants. CA activity in the complemented ΔCA strains can be probed using the Wilbur–Anderson assay and by isotope exchange membrane-inlet mass spectrometry (MIMS). Other potential uses for this new ΔCA-based screening system are also discussed.
Publisher: Wiley
Date: 09-2022
DOI: 10.1111/NPH.18427
Abstract: Mesophyll CO 2 conductance ( g m ) in C 3 species responds to short‐term (minutes) changes in environment potentially due to changes in leaf anatomical and biochemical properties and measurement artefacts. Compared with C 3 species, there is less information on g m responses to short‐term changes in environmental conditions such as partial pressure of CO 2 ( p CO 2 ) across erse C 4 species and the potential determinants of these responses. Using 16 C 4 grasses we investigated the response of g m to short‐term changes in p CO 2 and its relationship with leaf anatomy and biochemistry. In general, g m increased as p CO 2 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 CO 2 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 CO 2 responses of g m were also able to maintain their leaf water‐use efficiencies (TE i ) under low CO 2 . Our study advances understanding of CO 2 response of g m in erse C 4 species, identifies the key leaf traits related to this response and has implications for improving C 4 photosynthetic models and TE i through modification of g m .
Publisher: Wiley
Date: 05-02-2021
DOI: 10.1111/TPJ.15141
Publisher: Cold Spring Harbor Laboratory
Date: 04-10-2021
DOI: 10.1101/2021.10.03.462792
Abstract: Mesophyll CO 2 conductance (g m ) in C 3 species responds to short-term (minutes) changes in environment potentially due to changes in some leaf anatomical and biochemical properties and due to measurement artifacts. Compared to C 3 species, there is less information about g m responses to short-term changes in environment conditions like p CO 2 across erse C 4 species and the potential determinants of these responses. Using 16 erse C 4 grasses we investigated the response of g m to short-term changes in CO 2 and how this response related to the leaf anatomical and biochemical traits. For all the measured C 4 -grasses g m increased as CO 2 decreased however, the percent change in g m varied (+13% to +250%) and significantly related to percent changes in leaf transpiration efficiency (TE i ). The percent increase in g m was highest in grasses with thinner mesophyll cell walls and greater leaf nitrogen, activities of phosphoenolpyruvate carboxylase (PEPC), Rubisco and carbonic anhydrase, and a higher affinity of PEPC for bicarbonate. Our study demonstrates that CO 2 response of g m varies greatly across erse C 4 grasses and identifies the key leaf anatomical and biochemical traits related to this variation. These findings have implications for improving C 4 photosynthetic models, and in attempts to improve TE i through manipulation of g m .
No related grants have been discovered for Robert DiMario.