Photosynthesis across African cassava germplasm is limited by Rubisco and mesophyll conductance at steady state, but by stomatal conductance in fluctuating light
Open Access
- 1 March 2020
- journal article
- research article
- Published by Wiley in New Phytologist
- Vol. 225 (6), 2498-2512
- https://doi.org/10.1111/nph.16142
Abstract
Sub-Saharan Africa is projected to see a 55% increase in food demand by 2035, where cassava (Manihot esculenta) is the most widely planted crop and a major calorie source. Yet, cassava yield in this region has not increased significantly for 13 yr. Improvement of genetic yield potential, the basis of the first Green Revolution, could be realized by improving photosynthetic efficiency. First, the factors limiting photosynthesis and their genetic variability within extant germplasm must be understood. Biochemical and diffusive limitations to leaf photosynthetic CO2 uptake under steady state and fluctuating light in 13 farm-preferred and high-yielding African cultivars were analyzed. A cassava leaf metabolic model was developed to quantify the value of overcoming limitations to leaf photosynthesis. At steady state, in vivo Rubisco activity and mesophyll conductance accounted for 84% of the limitation. Under nonsteady-state conditions of shade to sun transition, stomatal conductance was the major limitation, resulting in an estimated 13% and 5% losses in CO2 uptake and water use efficiency, across a diurnal period. Triose phosphate utilization, although sufficient to support observed rates, would limit improvement in leaf photosynthesis to 33%, unless improved itself. The variation of carbon assimilation among cultivars was three times greater under nonsteady state compared to steady state, pinpointing important overlooked breeding targets for improved photosynthetic efficiency in cassava.Funding Information
- Bill and Melinda Gates Foundation (OPP1172157)
This publication has 90 references indexed in Scilit:
- Phenotypic approaches to drought in cassava: reviewFrontiers in Physiology, 2013
- Physiological basis of genetic variation in leaf photosynthesis among rice (Oryza sativa L.) introgression lines under drought and well-watered conditionsJournal of Experimental Botany, 2012
- Advancing Our Understanding and Capacity to Engineer Nature’s CO2-Sequestering Enzyme, RubiscoPlant Physiology, 2010
- Optimizing the Distribution of Resources between Enzymes of Carbon Metabolism Can Dramatically Increase Photosynthetic Rate: A Numerical Simulation Using an Evolutionary AlgorithmPlant Physiology, 2007
- Fitting photosynthetic carbon dioxide response curves for C3 leavesPlant, Cell & Environment, 2007
- PAPER PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Prospects for increasing photosynthesis by overcoming the limitations of RubiscoThe Journal of Agricultural Science, 2006
- Cassava breeding: opportunities and challengesPlant Molecular Biology, 2004
- In vivo temperature response functions of parameters required to model RuBP‐limited photosynthesisPlant, Cell & Environment, 2003
- Stomatal behavior and photosynthetic performance under dynamic light regimes in a seasonally dry tropical rain forestOecologia, 2000
- A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye bindingAnalytical Biochemistry, 1976