Photosynthetic labeling and partitioning of major sugars and monoterpenes in leaves of plantago lanceolata L

Abstract

Steady-state 14CO2 labeling was used to compare photosynthesis, C-partitioning, and export of greenhouse and field grown ribwort (Plantago lanceolata L.). In addition, to labeling starch and sucrose, ribwort produces a prominent alcohol sugar during photosynthesis and monoterpenes (iridoids). In P. lanceolata, the alcohol sugar, sorbitol, was heavily labeled relative to sucrose during 14CO2 feeding and appeared to be exported to sink tissues for both growth methods, but more label was partitioned to sorbitol in field grown plants. Ribwort synthesizes the iridoid glycosides (IGs), catalpol and aucubin, the 14C-labeling was primarily into sucrose and sorbitol that were readily exported with less than 1% partitioned into the iridoid fraction during steady-state 14CO2 feeding conditions for both greenhouse and field grown plants.