Voon, C. P. | bioRxiv Science

bioRxiv2020

Efficient cooperation of chloroplasts and mitochondria enhances ATP and sucrose production

Efficient photosynthesis requires a balance of ATP and NADPH production/consumption in chloroplasts and the exportation of reducing equivalents from chloroplasts is important for balancing stromal ATP/NADPH ratio. Here we showed that the overexpression of purple acid phosphatase 2 on the outer membranes of chloroplasts and mitochondria can streamline the production and consumption of reducing equivalents in these two organelles, respectively. A higher capacity of consumption of reducing equivalents in mitochondria can indirectly help chloroplasts to balance the ATP/NADPH ratio in stroma and recycle NADP+, the electron acceptors of the linear electron flow. A higher rate of ATP and NADPH production from the linear electron flow, a higher capacity of carbon fixation by the Calvin-Benson-Bassham cycle and a greater consumption of NADH in mitochondria, enhance photosynthesis in the chloroplasts, ATP production in the mitochondria, sucrose synthesis in the cytosol, and eventually boosting plant growth and seed yields in the overexpression lines.

plant biology↗

bioRxiv2017

ATP sensing in living plant cells reveals tissue gradients and stress dynamics of energy physiology

Growth and development of plants is ultimately driven by light energy captured through photosynthesis. ATP acts as universal cellular energy cofactor fuelling all life processes, including gene expression, metabolism, and transport. Despite a mechanistic understanding of ATP biochemistry, ATP dynamics in the living plant have been largely elusive. Here we establish live MgATP2- assessment in plants using the fluorescent protein biosensor ATeam1.03-nD/nA. We generate Arabidopsis sensor lines and investigate the sensor in vitro under conditions appropriate for the plant cytosol. We establish an assay for ATP fluxes in isolated mitochondria, and demonstrate that the sensor responds rapidly and reliably to MgATP2- changes in planta. A MgATP2- map of the Arabidopsis seedling highlights different MgATP2- concentrations between tissues and in individual cell types, such as root hairs. Progression of hypoxia reveals substantial plasticity of ATP homeostasis in seedlings, demonstrating that ATP dynamics can be monitored in the living plant.\n\nOne-sentence SummarySensing of MgATP2- by fluorimetry and microscopy allows dissection of ATP fluxes of isolated organelles, and dynamics of cytosolic MgATP2- in vivo.\n\nFunding AgenciesThis work was supported by the Deutsche Forschungsgemeinschaft (DFG) through the Emmy-Noether programme (SCHW1719/1-1; M.S. and GR4251/1-1; C.G.), the Research Training Group GRK 2064 (M.S.; A.J.M.), the Priority Program SPP1710 (A.J.M.) and a grant (SCHW1719/5-1; M.S.) as part of the package PAK918. The Seed Fund grant CoSens from the Bioeconomy Science Center, NRW (A.J.M.; M.S.) is gratefully acknowledged. The scientific activities of the Bioeconomy Science Center were financially supported by the Ministry of Innovation, Science and Research within the framework of the NRW Strategieprojekt BioSC (No. 313/323-400-002 13). A.Co. received funding by the Ministero dellIstruzione, dellUniversita e della Ricerca through the FIRB 2010 programme (RBFR10S1LJ_001) and Piano di Sviluppo di Ateneo 2015 (Universita degli Studi di Milano). M.Z. received funding by the Ministero dellIstruzione, dellUniversita e della Ricerca (Italy) through the PRIN 2010 programme (PRIN2010CSJX4F). S.W. and T.N. received travel support by the Deutscher Akademischer Austauschdienst (DAAD). V.D.C. was supported by the European Social Fund, Operational Programme 2007/2013, and an Erasmus+ Traineeship grant. M.D.F was supported by The Human Frontier Science Program (RPG0053/2012), and the Leverhulme Foundation (RPG-2015-437). I.M.M. was supported by a grant from the Danish Council for Independent Research - Natural Sciences. V.C.P. was supported by the Innovation and Technology Fund (Funding Support to Partner State Key Laboratories in Hong Kong) of the HKSAR.\n\nAbbreviationsAAC - ADP/ATP carrier; AK - adenylate kinase; cAT - carboxyatractyloside; CCCP - carbonyl cyanide m-chlorophenyl hydrazone; CFP - cyan fluorescent protein; CLSM - confocal laser scanning microscopy; ETC - electron transport chain; FRET - Forster Resonance Energy Transfer; LSFM - light sheet fluorescence microscopy.

plant biology↗