Darkened Leaves Use Different Metabolic Strategies for Senescence and Survival.

Law SR, Chrobok D, Juvany M, Delhomme N, Lindén P, Brouwer B, Ahad A, Moritz T, Jansson S, Gardeström P, Keech O

Plant Physiol. 177 (1) 132-150 [2018-05-00; online 2018-03-09]

In plants, an individually darkened leaf initiates senescence much more rapidly than a leaf from a whole darkened plant. Combining transcriptomic and metabolomic approaches in Arabidopsis ( Arabidopsis thaliana), we present an overview of the metabolic strategies that are employed in response to different darkening treatments. Under darkened plant conditions, the perception of carbon starvation drove a profound metabolic readjustment in which branched-chain amino acids and potentially monosaccharides released from cell wall loosening became important substrates for maintaining minimal ATP production. Concomitantly, the increased accumulation of amino acids with a high nitrogen-carbon ratio may provide a safety mechanism for the storage of metabolically derived cytotoxic ammonium and a pool of nitrogen for use upon returning to typical growth conditions. Conversely, in individually darkened leaf, the metabolic profiling that followed our 13C-enrichment assays revealed a temporal and differential exchange of metabolites, including sugars and amino acids, between the darkened leaf and the rest of the plant. This active transport could be the basis for a progressive metabolic shift in the substrates fueling mitochondrial activities, which are central to the catabolic reactions facilitating the retrieval of nutrients from the senescing leaf. We propose a model illustrating the specific metabolic strategies employed by leaves in response to these two darkening treatments, which support either rapid senescence or a strong capacity for survival.

Swedish Metabolomics Centre (SMC) [Service]

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PubMed 29523713

DOI 10.1104/pp.18.00062

Crossref 10.1104/pp.18.00062

pii: pp.18.00062
pmc: PMC5933110