Mung bean hypocotyls

As illustrated in Fig. 3, in both poplar stems and mung bean hypocotyls, basic isoforms became prevalent in mature, resting cells whereas in young, growing cells, neutral isoforms were predominant. 

Yoshida S. Isolation of smooth endoplasmic reticulum and tonoplast from etiolated mung bean hypocotyls. in Methods in Enzymology, Vol. 228 (Walter H, Johansson G, ed.), Academic Press, New York, 1994, pp. 482-489. 

Along the mung bean hypocotyl, the cell wall plasticity represents the limiting factor of cell growth potentials. Pectin molecules, known to control local cell wall pH s and to modulate phenolic cross-linking owing to the number of free acidic domains, were investigated. 

A / -D-glucan has been isolated from the cell walls of 3-day-old, mung-bean hypocotyls.76 Extracts of cell walls of older hypocotyls were deficient in this polysaccharide. The glucan contained 3-linked and 4-linked glucopyranosyl residues in the molar ratio of 1.0 1.7. However, the hypocotyl tissue from which the glucan was extracted contained both primary and secondary walls, and therefore, the polymer cannot be definitely characterized as a primary cell-wall component. 

Protein fractions having lectin activity have been extracted from mitochondria, plasma, and Golgi membranes, and from the endoplasmic reticulum of mung-bean hypocotyls, as well as from total-membrane fractions from a variety of plant tissues.257 The carbohydrate specificity of the lectin fractions differs with the membrane type. It is conceivable that, in addition to cell-wall lectin-membrane interactions, there may also be membrane lectin-cell wall, noncovalent bonds. 

Treatment of the roots of tomato and radish plants with BR led to elongation of the petioles and hypocotyls, and treatment of the bases of mung bean hypocotyl cuttings led to the elongation of the epicotyls (46,47,48). In cucumber hypocotyl segments, washing with water reduced the effect of BR treatment (49), and the uptake of BR has been studied in detail in maize roots, where it accumulated independently of energy supply and 30% was irreversibly bound (50). 

Transverse geotropism in stems is a characteristic response to ethylene. It has been reported that treatments with epibrassinolide at concentrations of 1-10 ppm accelerated ethylene production in etiolated mung bean hypocotyl segments by increasing ACC (1-aminocyclopropane-l-carboxylic acid) (7). Thus it is possible that the transverse geotropism and even the twining growth response evoked by brassinolide at 10 1-10° ppm were related to the production of ethylene. 

In 1971, using the auxin-induced ethylene-producing system of mung bean hypocotyls, Sakai and Imaseki [70] proposed that auxin induces a protein essential to ethylene formation and that the protein is rapidly inactivated with an apparent half-life of 35 min. A similar result was obtained with pea epicotyls [71]. The short-lived essential protein was later identified as ACC synthase [32,72,73]. Wound-induced ACC synthase of tomato fmits is also inactivated but with a slightly longer half-life (30-100 min) [74]. 

ARGl mung bean hypocotyl 20 min none reported 83,84... 

On the other hand, Sakai [11] and Sakai and Hanagate [12] partially purified two auxin-binding proteins from mung bean by affinity chromatography. Both proteins stimulated RNA-synthesis (24-39%) in isolated mung bean hypocotyls, but neither protein required lAA for this stimulatory effect [13]. 

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