The C4 biochemical pathway, and the anatomy of lemongrass (Cymbopogon citratus (DC) Stapf.) cultivated in temperate climates

• Published in: Plant biosystems 2003-01, Vol.137 (2), p.175-184
• Main Authors: Bertea, Cinzia Margherita, Buffa, Giorgio, Camusso, Wanda, Bossi, Simone, Scannerini, Silvano, Maffei, Massimo, Tesio, Manuela, D'Agostino, Giovanni, Mucciarelli, Marco
• Format: Article
• Language: English
• Subjects: Cymbopogon citratus; leaf anatomy; Lemongrass; NADP-ME variant; photosynthetic enzyme activities; Rubisco immunolocalisation
• ISSN: 1126-3504; 1724-5575
• DOI: 10.1080/11263500312331351441

Leaf anatomy (light and transmission electron microscopy, immunogold localisation of Rubisco) and physiology (C 4 photosynthetic enzyme activities, CO 2 assimilation and stomatal conductance) were studied in lemongrass, Cymbopogon citratus (DC) Stapf., cultivated in temperate climates (northwestern Italy). The leaf blade had an NADP-ME Kranz anatomy, with bundle sheath cells containing chloroplasts located in a centrifugal position. Dimorphic chloroplasts, agranal and starchy in the bundle sheath and granal starchless in the mesophyll cells, were also observed. Rubisco, as determined by immunolocalisation, occurred only in the bundle sheath chloroplasts. Pyruvate, orthophosphate dikinase (PPDK), NADP malic dehydrogenase (NADP-MDH), NADP malic enzyme (NADP-ME), PEP-carboxykinase (PCK), and NAD malic enzyme (NAD-ME) activities were also measured, indicating an NADP-ME C 4 photosynthetic pathway. Some kinetic properties and chemicalphysical parameters of lemongrass NADP-ME and NADP-MDH as well as CO 2 compensation point and stomatal conductance values confirmed these preliminary data. C. citratus appeared to be well adapted to the varying environmental conditions typical of temperate climates, by retaining high NADP-MDH and NADP-ME activities and a low CO 2 compensation point.