Effects of elevated CO<sub>2</sub> applied to potato roots on the anatomy and ultrastructure of leaves

Abstract

The root system of potato (Solanum tuberosum L. cv. Favorita) plants was treated with different O2 and CO2 concentrations for 35 d in aeroponic culture. Under 21 or 5 % O2 in the root zones, the thickness of leaves and palisade parenchyma significantly increased at 3 600 μmol(CO2) mol−1 in the root zone, compared with CO2 concentration 380 μmol mol−1 or low CO2 concentration (100 μmol mol−1). In addition, smaller cells of palisade tissue, more intercellular air spaces and partially two layers of palisade cells were observed in the leaves with root-zone CO2 enrichment. Furthermore, there was a significant increase in the size of chloroplasts and starch grains, and the number of starch grains per chloroplast due to elevated CO2 only under 21 % O2. In addition, a significant decline in the thickness of grana and the number of lamellas, but no significant differences in the number of grana per chloroplast were observed under elevated CO2 concentration. The accumulation of starch grains in the chloroplast under elevated CO2 concentration could change the arrangement of grana thylakoids and consequently inhibited the absorption of sun radiation and photosynthesis of potato plants.