Distribution and structure of mixed linkage glucan at different stages of elongation of maize root cells

Distribution and structure of mixed linkage glucan in the cell walls at different stages of elongation were investigated in the roots of 4-day-old seedlings of maize (Zea mays L.). Mixed linkage glucan was immunocytochemically detected already in the meristem, predominantly in the periclinal cell walls. The antibody binding by the cell walls increased in the zone of cell elongation initiation, was high during the whole process, and did not decrease in the cells whose elongation was over. The content of polysaccharide determined biochemically also rose from meristematic zone to the zone where elongation was over, amounting to 8% of dry weight and remained on the same level after the completion of cell elongation. At different stages of elongation growth, the structure of polysaccharide was not the same. In the beginning of elongation, molar ratio between trimer and tetramer (DP3/DP4) among the products of polysaccharide hydrolysis by lichenase was 3.56 +/- 0.04, and after its termination it became 3.04 +/- 0.09. According to literature data, such changes tell on the physical properties of polysaccharide, which along with a drastic activation of its deposition associated with the initiation of elongation make it possible to attribute the mixed linkage glucan to the factors directly affecting cell wall extensibility and therefore elongation growth.