Metabolic profiles of six African cultivars of cassava (Manihot esculenta Crantz) highlight bottlenecks of root yield

Authors

Toshihiro Obata, Max-Planck-Institute of Molecular Plant Physiology & University of Nebraska-LincolnFollow
Patrick A.W. Klemens, University of Kaiserslautern
Laise Rosado-Souza, Max-Planck-Institute of Molecular Plant Physiology
Armin Schlereth, Max-Planck-Institute of Molecular Plant Physiology
Andreas Gisel, International Institute of Tropical Agriculture & Institute for Biomedical Technologies, CNR
Livia Stavolone, International Institute of Tropical Agriculture & Institute for Sustainable Plant Protection, CNR
Wolfgang Zierer, University of Erlangen-Nuremberg
Nicolas Morales, Boyce Thompson Institute
Lukas A. Mueller, Boyce Thompson Institute
Samuel C. Zeeman, Institute of Molecular Plant Biology
Frank Ludewig, Institute for Biomedical Technologies, CNR & KWS SAAT SE
Mark State, Max-Planck-Institute of Molecular Plant Physiology
Uwe Sonnewald, University of Erlangen-Nuremberg
H. Ekkehard Neuhaus, University of Kaiserslautern
Alisdair R. Femie, Max-Planck-Institute of Molecular Plant PhysiologyFollow

ORCID IDs

https://orcid.org/0000-0001-8640-1750

https://orcid.org/0000-0003-1835-5339

https://orcid.org/0000-0001-9000-335X

Date of this Version

2020

Citation

The Plant Journal (2020) 102, 1202–1219 doi: 10.1111/tpj.14693

Comments

2020 The Authors

Abstract

Cassava is an important staple crop in sub-Saharan Africa, due to its high productivity even on nutrient poor soils. The metabolic characteristics underlying this high productivity are poorly understood including the mode of photosynthesis, reasons for the high rate of photosynthesis, the extent of source/sink limitation, the impact of environment, and the extent of variation between cultivars. Six commercial African cassava cultivars were grown in a greenhouse in Erlangen, Germany, and in the field in Ibadan, Nigeria. Source leaves, sink leaves, stems and storage roots were harvested during storage root bulking and analyzed for sugars, organic acids, amino acids, phosphorylated intermediates, minerals, starch, protein, activities of enzymes in central metabolism and yield traits. High ratios of RuBisCO:phosphoenolpyruvate carboxylase activity support a C3 mode of photosynthesis. The high rate of photosynthesis is likely to be attributed to high activities of enzymes in the Calvin–Benson cycle and pathways for sucrose and starch synthesis. Never- theless, source limitation is indicated because root yield traits correlated with metabolic traits in leaves rather than in the stem or storage roots. This situation was especially so in greenhouse-grown plants, where irradiance will have been low. In the field, plants produced more storage roots. This was associated with higher AGPase activity and lower sucrose in the roots, indicating that feedforward loops enhanced sink capacity in the high light and low nitrogen environment in the field. Overall, these results indicated that car- bon assimilation rate, the K battery, root starch synthesis, trehalose, and chlorogenic acid accumulation are potential target traits for genetic improvement.