In Arabidopsis, the plastidial isoform of phosphoglucose isomerase, PGI1, mediates growth and photosynthesis, likely due to its involvement in the vascular production of cytokinins (CK). To examine this hypothesis, we characterized pgi1-2 knockout plants impaired in PGI1 and pgi1-2 plants specifically expressing PGI1 in root tips and vascular tissues. Moreover, to investigate whether the phenotype of pgi1-2 plants is due to impairments in the plastidial oxidative pentose phosphate pathway (OPPP) or the glycolytic pathway, we characterized pgl3-1 plants with reduced OPPP and pfk4pfk5 knockout plants impaired in plastidial glycolysis. Compared with wild-type (WT) leaves, pgi1-2 leaves exhibited weaker expression of photosynthesis- and 2-C-methyl-D-erythritol 4-P (MEP) pathway-related proteins, and stronger expression of oxidative stress protection-related enzymes. Consistently, pgi1-2 leaves accumulated lower levels of chlorophyll, and higher levels of tocopherols, flavonols and anthocyanins than the WT. Vascular- and root tip-specific PGI1 expression countered the reduced photosynthesis, low MEP pathway-derived CK content, dwarf phenotype and the metabolic characteristics of pgi1-2 plants, reverting them to WT-like levels. Moreover, pgl3-1, but not pfk4pfk5 plants phenocopied pgi1-2. Histochemical analyses of plants expressing GUS under the control of promoter regions of genes encoding plastidial OPPP enzymes exhibited strong GUS activity in root tips and vascular tissues. Overall, our findings show that root tip and vascular PGI1-mediated plastidial OPPP activity affects photosynthesis and growth through mechanisms involving long-distance modulation of the leaf proteome by MEP pathway-derived CKs.

COMAV Universitat Politècnica de València Valencia Spain

Czech Advanced Technology and Research Institute Palacky University Šlechtitelů 27 78371 Olomouc Czech Republic

Institute for Mediterranean and Subtropical Horticulture La Mayora CSIC UMA Campus de Teatinos Avda Louis Pasteur 49 29010 Málaga Spain

Instituto de Agrobiotecnología CSIC Gobierno de Navarra Iruñako etorbidea 123 31192 Mutiloabeti Nafarroa Spain

Instituto de Agrobiotecnología CSIC UMA Campus de Teatinos Avda Louis Pasteur 49 29010 Málaga Spain

Instituto de Agrobiotecnología CSIC Universidad de Sevilla 41092 Sevilla Spain

Citace poskytuje Crossref.org