PHOTOSYNTHETIC CHARACTERISTICS OF THE PALISADE MESOPHYLL AND SPONGY MESOPHYLL IN THE CAM C4 INTERMEDIATE PLANT, PEPEROMIA-CAMPTOTRICHA/

Several photosynthetic parameters were examined in the different tissu e layers of leaves from the recently characterized crassulacean acid m etabolism/C4 intermediate plant, Peperomia camptotricha (Nishio and Ti ng, 1987). Light appears to control the development of certain photosy nthetic characteristics within the tissue layers, while factors other than light seem to dictate others. Analysis of the chlorophyll content (including P700) and chlorophyll-proteins indicated that more light h arvesting chlorophylls were associated with reaction centers in the ti ssues that were shaded by overlying tissue. Electron transport activit y and chlorophyll-protein analysis indicated that the ratio of photosy stem I to photosystem II in the spongy mesophyll (the abaxial tissue t ype and hence most shaded) was elevated relative to the overlying chlo rophyll-rich median palisade mesophyll. The elevated photosystem I rel ative to photosystem II in the spongy mesophyll of Peperomia camptotri cha may be related to C4 metabolism and an increased requirement for A TP.