DYNAMICS OF WINTER RYE PENTOSAN FORMATION DURING GRAIN MATURATION

The study was conducted in 2018-2019 in the Republic of Tatarstan to assess the dynamics of total and water-soluble pentosans accumulation at different stages of grain formation to develop methods for breeding rye with a given level of these polysaccharides. The material for the study was six varieties of winter rye (Tatarskaya 1, Radon, Pamyati Kunakbaeva, Podarok, Ogonek, Marusenka). Grain samples were collected at the milk, wax, full and physiological (10 days after harvesting) maturity phases. From the middle part of the ear of each variety, 600 grains were isolated, separated by the morphological and histological method into the embryo, endosperm and shells for subsequent analysis of pentosans. The monosaccharide composition was determined by the method of high-performance anion exchange chromatography, the content of total and water-soluble pentosans - by the orcinol chloride method, the viscosity of the aqueous extract - on a sinusoidal viscometer. The content of oligo- and polysaccharides in aqueous extracts of rye meal was 52 ... 74% of the total amount of extracted carbohydrates. The amount of xylose in the varieties Tatarskaya 1, Radon and Pamyati Kunakbaeva was at the level of 14 ... 16 mg/ml, Ogonek, Podarok and Marusenka - 9 ... 11 mg/ml. The viscosity of the extracts correlated with the level of water-soluble pentosans (r = 0.972 and r = 0.615 in 2018 and 2019). The share of arabinoxylans in grain hulls increased from milk (34.3%) to physiological maturity (39.8%). The study revealed significant varietal differences in the accumulation of pentosans and their spatiotemporal dynamics in grain. The level of total pentosans in the endosperm decreased from 7% (milk ripeness) to 4.3% (physiological maturity), in the embryo - from 14.5% (wax ripeness) to 13.5% (physiological maturity). In the hulls, the water-soluble pentosans content decreased from milk to full maturity (from 5.04% to 3.15%), but increased to 3.9% by physiological maturity. The peak concentration of water-soluble pentosans in the endosperm and embryo was observed at full ripeness (4.8% and 2.6%, respectively), after which it decreased towards physiological maturity.