Regulatory role of Endogenous Carbohydrate-binding Proteins and Phytohormones on the Elongation of Coleoptiles cells

Author: Mariam Gaidamashvili
Co-authors: E. Khurtsidze
Keywords: carbohydrate-binding proteins, phytohormones, coleoptile, elongation
Annotation:

One of the main branches of plant physiology is the study of phytohormone influence on the regulation of plant life cycle. Interest in this process is conditioned by the fact that hormone–inhibitor balance determines physiological and morphogenetic processes in the plant. According to the recent literature data, besides of the 5 main phytohormones known so far (Auxins, gibberelines, cytochinins, Ethylen, Abscyze acid, Jasmine acid, brasinolydes) new class of hormones was discovered, that includes small signaling molecules of polypeptide nature. Polypeptide signaling is an emerging field in plant biology, particularly in the areas of plant self-defense, fertilization, growth and development. Among those phytohormones mentioned above, auxins are recognized as a major class of plant growth hormones and elicit a wide range of reactivity being responsible for growth and differentiation including cell elongation and cellular differentiation, but the plant science as a whole has much to learn about concrete mechanisms of an action of this plant hormone in the processes of growth and development. Now it becomes more evident that biomolecules containing carbohydrates and with them specifically bending proteins - lectins play key role in control of those physiological processes described above. According to basic data, analogy between nature and molecular mechanisms in the action of plant and animal hormones could be found. Also must be mentioned, that all hormones found in animal cells and their receptors are glycoproteins, main parts of which are lectins. Thus, consideration of plant lectins as plant hormones is of great interest and represents a new dimension in plant physiology. Based on preliminary works regarding investigation of lectin dynamics in dependence with their content and activity in different organs (root, stem, bud, inflorescent) of mulberry at various stages of their development, supposed possible physiological role of mulberry lectins, which depict their participation in growth and development processes. An activity of exogenic Auxins and growth inhibitors in leaves and inflorescent of mulberry at the different stages of ontogenesis (Apical bud, preflorescence, florescence and fruitage) have been studied. Maximum activity of stimulating substances is revealed in leaves and inflorescent during the growing period (300-225%). Also in the following phases their content reduces (180-150%). The presence of correlation between the lectin content and the activity of endogenic Auxins in growing leaves and inflorescent is shown. Have been studied an effect of galactose specific mulberry lectin on plant coleoptiles growth elongation. Quality of purification of mulberry seeds of Gal-specific lectin (MNL) promotes sharp stimulation of growth elongation of wheat coleoptiles. Also has to be mentioned that lectin inhibited by carbohydrate loses its ability to influence growth elongation of wheat coleoptiles. Thus participation of MNL in growth elongation processes is realized by sugar-bounded centers.