Received: 19 June 2017 | Revised: 16 February 2018 | Accepted: 20 February 2018 DOI: 10.1002/fes3.130 ORIGINAL RESEARCH Toward improving photosynthesis in cassava: Characterizing photosynthetic limitations in four current African cultivars Amanda P. De Souza1 | Stephen P. Long1,2 1Departments of Crop Sciences and Plant Biology, Carl R Woese Institute for Abstract Genomic Biology, University of Illinois at Despite the vast importance of cassava (Manihot esculenta Crantz) for smallholder Urbana-Champaign, Urbana, IL, USA farmers in Africa, yields per unit land area have not increased over the past 55 years. 2 Lancaster Environment Centre, Lancaster Genetic engineering or breeding for increased photosynthetic efficiency may repre- University, Lancaster, UK sent a new approach. This requires the understanding of limitations to photosynthesis Correspondence within existing germplasm. Here, leaf photosynthetic gas exchange, leaf carbon and Stephen P. Long, Departments of Crop nitrogen content, and nonstructural carbohydrates content and growth were analyzed Sciences and Plant Biology, Carl R Woese Institute for Genomic Biology, University in four high- yielding and farm- preferred African cultivars: two landraces (TME 7, of Illinois at Urbana-Champaign, Urbana, TME 419) and two improved lines (TMS 98/0581 and TMS 30572). Surprisingly, IL, USA. A Email:
[email protected] the two landraces had, on average, 18% higher light-saturating leaf CO2 uptake ( sat) than the improved lines due to higher maximum apparent carboxylation rates of Funding information Bill and Melinda Gates Foundation, Grant/ Rubisco carboxylation (Vcmax) and regeneration of ribulose- 1,5- biphosphate ex- Award Number: OPP1060461 pressed as electron transport rate (Jmax). TME 419 also showed a greater intrinsic water use efficiency.