Ontogenetic changes in starch content and activity of amylolytic enzymes in pea leaves in the aspect of plant productivity

The article presents generalized data of long-term experiments on the study of ontogenetic dynamics of the content of assimilating starch and the activity of amylolytic enzymes in leaves of various varieties of leafy and semi-leafless peas. The studies were carried out under the conditions of field and vegetation experiments. It has been established that the content of assimilating starch in pea leaves depends on the variety, the phase of plant development, and the conditions of soil moisture. A positive correlation was established between its concentration at the beginning of seed filling and the final productivity of seeds (r = 0.47-0.71). The ontogenetic dynamics was noted - the accumulation of maximum concentrations by the period of fruit formation - seed filling (up to 16-18% of dry weight) and a strong decrease in the final period of vegetation. Conditions of low aridity stimulated the accumulation of starch in the leaves. Changes in the starch content and the activity of amylolytic enzymes in plant ontogeny are interrelated. During the filling of seeds, a decrease in the starch content in the leaves was accompanied by a 2-4-fold increase in α-amylase activity and total amylolytic activity. During the flowering period, a positive significant correlation (r = 0.49) was noted between the activity of α-amylase and the seed productivity of pea varieties. It is assumed that amylolytic enzymes prevent excessive accumulation of starch in chloroplasts and contribute to the preservation of their high photosynthetic activity. In the tendrils of semi-leafless pea cultivars, the accumulation of starch and its outflow were weak, which is associated with differences in the anatomical structure of the leaflets and tendrils. The period of intensive decrease in the starch content in the leaves coincided with their yellowing and aging. This suggests that starch is one of the last reserves of carbohydrates, which is used in plant metabolism after photo assimilation of CO2 stops.