АННОТАЦИЯ
Elongation or expansion growth of plant cells occurs after cell division and precedes further cell differentiation. During elongation growth, plant cells may enlarge their size several hundred times compared to initial. Elongation implies a reorganization of the architecture of the cell wall, which includes the rearrangement of bonds between existing polysaccharides with the simultaneous incorporation of new building material, allowing the cell to elongate without losing its previous wall thickness. The mechanisms underlying elongation growth are studied mainly in dicotyledonous plants whose cells are surrounded by type I primary cell walls, while cereals with cell walls of type II get less attention. These two cell wall types differ from each other by matrix polysaccharides: type I contains xyloglucans and pectins as the major components. Type II cell walls are populated mainly by mixed-linkage glucans and glucuronoarabinoxylans, while xyloglucans and pectins are present at low levels. The unique composition of type II primary cell wall characteristic of grasses suggests that they employ specific mechanisms for cell enlargement. We characterized the transcriptomes in five zones along maize root, clustered the expression of genes for numerous glycosyltransferases and glycosylhydrolases, performed extensive immunohistochemical analysis and hydrolytic activity assays to relate the changes in cell wall polysaccharides to critical stages of cell development in Poaceae. Cell walls in meristem and early elongation zone of maize represent a mixture of type I and type II specific polysaccharides. Xyloglucans and homogalacturonans are synthesized there actively together with mixed-linkage glucans and glucuronoarabinoxylans. Rhamnogalacturonans-I with the side-chains of branched 1,4-galactan and arabinan persisted in cell walls throughout the development. However, the dynamics of pectin-related hydrolases indicates that pectins undergo continuous active turnover. Thus, the machinery to generate and degrade the type I primary cell wall constituents is completely established and operates in maize roots. The expression of glycosyltransferases responsible for mixed-linkage glucan and glucuronoarabinoxylan synthesis peaks at active or late elongation. Two separate gene sets potentially responsible for the biosynthesis and degradation of glucuronoarabinoxylans for primary and secondary cell wall deposition in maize root were revealed. Type II specific polysaccharides exist in cell walls of maize root already in the meristem; however, they become dominating only when the elongation rate reaches a maximum. Growth cessation is coupled to the diversification of GAX molecules in cell walls of different tissues. Thus, the polysaccharide ensemble of cell walls in maize root is dynamically changed in the course of elongation growth. Each stage of cells development corresponds to a specific set of glycosyltransferases and hydrolases participating in cell wall rearrangement.
ЦИТАТА
ELONGATION GROWTH OF MAIZE ROOT: CELL WALL DYNAMICS REVEALED BY TRANSCRIPTOME ANALYSIS / L. Kozlova, A. Nazipova, O. Gorshkov, A. Petrova, T. Gorshkova // The 7th International Conference on Plant Cell Wall Biology. : Program and Abstracts. – 2021. – P.
