Development of sugar beet leaves: contents of hormones, localization of abscisic acid, and the level of products of photosynthesis

ABSTRACTThe level of hormones in the tissues of sugar beet leaves of different age in parallel with their growth and metabolic activity was assayed; the latter was analyzed, measuring the contents of sugars and N-containing compounds, and the activities of Rubisco and proteases. The highest auxin and ABA concentration was detected in the actively growing upper leaf, while high level of cytokinins was maintained in the middle and upper leaves characterized by intensive photosynthesis. Leaf senescence being manifested in decline of chlorophyll content, decrease of photosynthesis and activation of proteolysis was accompanied by a decline in concentration of cytokinins. Glucose level gradually increased from upper (younger) to a lower (elder) leaves; this was accompanied with the signs of senescence on the background of decreased cytokinins level. Immuno-histochemical technique revealed increased level of abscisic acid in phloem parenchyma of the lowest leaf. The results suggest a possible involvement of auxi...