PGI1-mediated vascular pentose phosphate pathway activity determines growth, photosynthesis and metabolism through 2-C-methyl-D-erythritol 4-P pathway action in Arabidopsis

Abstract

Phosphoglucose isomerase is involved in the early steps of glycolysis and regeneration of glucose-6-phosphate pools in the pentose phosphate pathway (PPP). In Arabidopsis, plastidial phosphoglucose isomerase (PGI1) is an important determinant of growth, metabolism and photosynthesis, probably due to its involvement in the synthesis of 2-C-methyl-D-erythritol 4-P (MEP)-derived hormones in root tips and vascular tissues (Bahaji et al., 2015; Bahaji et al., 2018). To test this hypothesis, we conducted proteomic and metabolic characterization of PGI1-null pgi1-2 plants. We also characterized pgi1-2 plants ectopically expressing PGI1 under the control of a root tip- and vascular tissue-specific promoter. Furthermore, we characterized pfk4/pfk5 knockout plants impaired in the early steps of plastidial glycolysis, and pgl3-1 plants with reduced activity of the plastidial PPP enzyme 6-phosphogluconolactonase 3. The overall data obtained in this work provide strong evidence that root tip and vascular PGI1-mediated plastidial PPP determines growth, development and photosynthesis through MEP pathway action.