Adaptation of Plantago plants to environmental conditions: the role of carbohydrate balance

Sorbitol is a linear sugar alcohol which is, together with sucrose, the primary photosynthetic product in the Plantaginaceae family. Sorbitol and sucrose are used for long-distance transport of photosynthetically fixed carbon via phloem. Many plant species accumulate sugar alcohols during drought or salt stresses, and it leads to higher tolerance to these stress conditions. The aim of this diploma thesis is to describe selected metabolic and structure differences with a focus on the sorbitol and sucrose balance, in two Plantago species - glycophytic Plantago lanceolata and halophytic Plantago maritima, which differ in life strategies. The plants were cultivated hydroponically in Araponics boxes. Previous results of our team show, that sorbitol accumulates in Plantago leaves up to ten-times higher concentrations compared with sucrose. This difference is deepened when the plants are exposed to salt stress. Sorbitol to sucrose ratios vary between vascular tissue and phloem sap. We assume that increased salt tolerance of P. maritima is based on the different distribution of assimilates through the plant, and by their partitioning between metabolic, storage and transport pools in mature leaf, which also manifests under non-stress conditions. In both genotypes, I compared growth rates under standard..