Article,
Basic types of structural changes in the leaf mesophyll during adaptation of eastern Pamir plants to mountain conditions
Russian Journal of Plant Physiology, (2003)
Abstract
Abstract?Quantitative characteristics of mesophyll structure were compared in leaves of eleven alpine plant species grown under natural conditions in the Eastern Pamirs at various altitudes, from 3800 to 4750 m. Basic types of changes in mesophyll structure, associated with plant adaptation to mountain conditions, were charac- terized. These changes manifested themselves in different numbers of cell layers and cell sizes in the palisade tissue and, as a consequence, in changed leaf thickness and cell number per unit of leaf area. Three plant groups were identi?ed by the changes in the leaf structural characteristics depending on the type of mesophyll struc- ture, ecological group of plant species, and altitude of plant habitat. The ?rst group comprised alpine xerophytes with an isopalisade structure, in which the volume of palisade cells decreased and their number per unit of leaf area increased with the altitude of plant habitat. The number of mesophyll layers and leaf thickness decreased or did not change with altitude. The second group comprised subalpine plant species with a dorsoventral struc- ture of mesophyll; these species occur below the line of continuous night frost. In these plant species, the num- ber of mesophyll layers, leaf thickness, and cell number per unit of leaf area increased with altitude. The third group comprised mesophyte plants with a dorsoventral and homogenous mesophyll structure, which are encountered in a wide range of habitats, including the nival belt (from 4700 to 5000 m). In this group, cell vol- ume increased and cell number per unit of leaf area decreased with altitude. We present a general scheme of leaf structural changes, which explains the changes in the quantitative characteristics of mesophyll as a function of altitude and highland environmental conditions.
