Mung Bean Roots Research Articles

Effect of K+ and H+ stress and role of Ca2+ in the regulation of intracellular K+ concentration in mung bean roots

The effects of external K+, H+ and Ca2+ concentrations on the intracellular K+ concentration, [K+]i, and the K+‐ATPase activity in 2‐day‐old mung bean roots [Vigna mungo (L.) Hepper] were investigated. [K+]i, in mung bean roots was markedly decreased by external K+ or H+ stress and did not recover the initial value even after the stress was removed. This decrease in [K+]i, gradually disappeared with the addition of (Ca2+. Ca2+ may offset the harmful effects of ion stress. Ca2+ seems to have two effects on K+ transport; control of K+ permeability and activation of K+ uptake, although K+‐ATPase activity was inhibited by Ca2+ concentrations higher than 10–4 M. We suggest that Ca2+ activates K+ uptake indirectly through the acidification of the cytoplasm.

Differential control of length and number in adventitious roots of mung bean

Initiation and development of adventitious roots can be controlled by interaction between auxin and boric acid. The combinations of indoleacetic acid concentrations and boron which yield maximal numbers of roots per cutting, maximal individual lengths per root and maximal total root lengths per cutting are very similar. Using indolebutyric acid and boron, however, individual length and number may be manipulated almost independently of one another, since maxima for these result from very different combinations of concentrations.

Protein Dysfunction and Inhibition of Amino Acid Incorporation in Root Segments from Wheat and Mung Bean Seedlings caused by some Amino Acid Analogues

The effects of para-fluorophenylalanine (p-FPA) and azetidine-2-carboxylic acid (AZ) on acid phosphatase and peroxidase activity, and on L-leucine incorporation, in root segments of Triticum aestivum L. cv. Fenman and Vigna radial a (L.) Wilczek, were studied. Incubation with 50 mmol−3 AZ significantly reduced phosphatase and peroxidase activities in wheat roots, but with 20 mol m−3p-FPA, only the peroxidase activity was reduced. In mung bean roots, phosphatase activity was inhibited by both AZ and p-FPA. Effects of the ortho- and meta- isomers of FPA on wheat root phosphatase and peroxidase, and on mung bean phosphatase, were also examined. Leucine uptake and incorporation were not inhibited by 5 h pre-incubation with either p-FPA or AZ, but were inhibited after 24 h of pre-incubation. The results support the view that, in the shorter term, the analogues inhibit enzyme activity by becoming incorporated to produce non-functional protein and, in the longer term, metabolism is further affected by inhibition of protein synthesis.

Nucleolar Persistence in Meristems of Mung Bean

SUMMARYPersistent nucleoli in mitotic cells of primary root, secondary root, and shoot apical meristems of mung bean (Phaseolus aureus Roxb.) were quantified in plants of 4, 8, and 14 days of age. There was no statistical difference in the percentage of persistent nucleoli in primary roots (81.5–89.4%) and secondary roots (82.490.1%). Shoot apical meristems had 6.1–8.3% persistent nucleoli at metaphase, a significantly lower percentage of persistent nucleoli than root meristems. These results parallel other variations between nuclei of shoot and root meristems. Persistent nucleoli of 4- day- old primary root meristems stained positively with silver nitrate. Although this technique has been used as an indication of synthetically active nucleoli, ultrastructural evidence in mung bean indicates that persistent nucleoli are structurally different than synthetically active interphase nucleoli. Thus, means other than silver nitrate staining, should be used to indicate synthetically active nucleoli.

Growth and lignification in seedlings exposed to eight days of microgravity.

Four-day-old pine seedlings and mung bean and oat seeds were prepared for flight on the third Space Transport System Mission (STS-3). The seedlings and seeds were planted in six mini-growth chambers (two chambers per species) which were placed in a plant growth unit (PGU). Another set of seedlings and seeds was prepared and placed in another PGU as the 1 g control. The flight PGU was positioned in the orbiter mid-deck locker area about 11 h prior to launch. The pine seedlings and germinating mung bean and oat seeds were exposed to 194 h of microgravity. The PGU was received at a temporary laboratory about 75 min post-landing. Plants were observed, photographed and the atmospheric gases analyzed at the landing site. The plants were then brought to our Houston laboratory where they were measured and analyzed for lignin and protein content and for phenylalanine ammonia-lyase (PAL) and peroxidase activities. Flight seedlings were shorter than the controls in all three species. Twenty-five to 40 per cent of the mung bean and oat roots were growing upward, and the mung beans showed signs of disorientation. Flight mung beans showed a significant reduction in lignin content in comparison to the controls, and PAL and peroxidase activities were reduced in flight pine seedlings. The results generally support the postulate that lignin synthesis is reduced in near-weightlessness and show other interesting findings.

Cytological and ultrastructural studies on root tissues.

The anatomy and fine structure of roots from oat and mung bean seedlings, grown under microgravity conditions for 8 days aboard the Space Shuttle, was examined and compared to that of roots from ground control plants grown under similar conditions. Roots from both sets of oat seedlings exhibited characteristic monocotyledonous tissue organization and normal ultrastructural features, except for cortex cell mitochondria, which exhibited a 'swollen' morphology. Various stages of cell division were observed in the meristematic tissues of oat roots. Ground control and flight-grown mung bean roots also showed normal tissue organization, but root cap cells in the flight-grown roots were collapsed and degraded in appearance, especially at the cap periphery. At the ultrastructural level, these cells exhibited a loss of organelle integrity and a highly-condensed cytoplasm. This latter observation perhaps suggests a differing tissue sensitivity for the two species to growth conditions employed in space flight. The basis for abnormal root cap cell development is not understood, but the loss of these putative gravity-sensing cells holds potential significance for long term plant growth orientation during space flight.

Water and solute flow through mung bean roots under applied pressure

The technique of applying hydrostatic pressure on the root medium to study water and solute flows through excised plant roots and to study various characteristics of roots in relation to flow has been used by many workers but flows in excised roots have not been compared with those in intact transpiring plants. In the present study this comparison has been made using mung bean roots. Results show that excised roots under pressure lack the ion selectivity which is observed in intact plant roots and conduct salt many times higher than salt flows through intact plant roots. The role of stem resistance in the rates of water and salt flow through roots has been discussed. The suitability of this technique for solute flow studies through mung bean roots is questioned.

Growth and development of plants flown on the STS-3 space shuttle mission

Pre-germinated pine seedlings and germinating oat and mung bean seeds were flown on the STS-3 Space Shuttle mission. Overall, the seedlings grew and developed well in space. Some oat and mung bean roots, however, grew upward. Lignin content was slightly lower in flight tissues and protein content was higher.

Barium effects inPhaseolus aureus, Cephalandra indica,Canna indica, Beta vulgaris, Triticum aestivum andLactuca sativa

Barium chloride at 0.1 mM concentration inhibited elongation of mungbean (Phaseolus aureus) roots more strongly than elongation of hypocotyls. Root growth was completely inhibited at 80 mM and there was no germination at 100 mM. Respiration rates which were directly proportional to seedling vigour declined at varying degrees at the growth-inhibitory concentrations of BaCl2. Barium retarded senescence in isolated leaf discs ofCephalandra indica by maintaining the chlorophyll level in darkness. The carotenes were similarly protected from degradation by Ba in darkness whereas xanthophylls were retained both in darkness and light. Ba also protected anthocyanin pigments in the staminode discs ofCanna indica flowers and reduced to a variable extent the leakage of betacyanin pigment fromBeta vulgaris root discs caused by various membrane active chemicals. Applied either alone or in combination with IAA, Ba inhibited cell enlargement in wheat (Triticum aestivum) coleoptile sections. Barium-induced inhibition of lettuce (Lactuca sativa) hypocotyl elongation was largely overcome by GA3.

Observations on the enzymatic synthesis of a β-1,4-glucan by a soluble preparation from mung bean ( Phaseolus aureus)

An enzyme extract of mung bean roots and hypocotyls ( Phaseolus aureus) that catalyzes the synthesis of a β-1,4-glucan from guanosine 5′-diphosphate- d-glucose was prepared by a modification of the method of T.-Y. Liu and W. Z. Hassid (1970, J. Biol. Chem. 245, 1922–1925). Its activity was not increased by any of those factors that have contributed to the marked improvement in the performance of various cell-free polysaccharide-synthesizing systems from other organisms. Evidence is presented to suggest that in the mung bean system a stable precursor of the cell wall polysaccharide or intermediate in its synthesis is formed by incubation of the enzyme with guanosine 5′-diphosphate- d-mannose.

Development of root nodules of mung bean (Vigna radiata): a reinvestigation of endocytosis

The release of rhizobia from infection threads of mung bean (Vigna radiata) root nodules is an endocytotic process. The peribacteroid membrane surrounding the released bacteria is initially derived from the host plasma membrane which surrounds the infection thread and not from the nuclear envelope as previously reported by Prasad and De. Endoplasmic reticulum (ER) profiles and Golgi vesicles fuse with the infection thread cell wall and adjacent host plasma membrane. Although some ER profiles were continuous with the outer membrane of the nuclear envelope, no continuities of the nuclear envelope with the infection thread, the host plasma membrane, or the peribacteroid membrane were observed. Furthermore, no blebbing of the nuclear envelope was observed.

Isolation and Sustained Division of Phaseolus aureus (Mung Bean) Root Protoplasts

Summary A simple enzymatic method is described for the isolation of protoplasts from radicles of 24 hours germinated Phaseolus aureus (Mung Bean) seeds. 8-9 X 10 4 protoplasts were obtained routinely per root explant. Media based on the formulations of Donn (1978) and Kao and Michayluk (1975) supported protoplast division, with liquid over agar cultures being superior to liquid medium alone. Transfer of cell colonies to a modified White’s medium (Wood and Braun, 1961) enabled callus to be recovered from cell colonies. The use of roots for protoplast isolation is discussed in relation to other sources of experimental material such as greenhouse-grown plants and axenic shoots.

Reduction of Hydraulic Conductivity during Inhibition of Exudation from Excised Maize and Barley Roots

The uncoupler, carbonyl cyanide m-chlorophenyl hydrazone (CCCP) is shown to reduce the hydraulic conductivity of barley, maize, mung bean, and onion roots. In barley and maize, the reduction in exudation from excised roots is partly due to the reduction in the permeability of the root to water (I(p)), but it can be inferred that the rate of salt release to the xylem, is also inhibited. The action of CCCP on L(p) is suggested to be mainly in blocking the symplasmic pathway at the plasmodesmata.

Boron ? Key element in the actions of phytochrome and gravity?

Hypocotyl sections from dark-grown mung bean (Vigna radiata (L.) Wilczek) seedlings grown without boron exhibit little or no increase in the translocation of fluorescein in phloem cells following gravitational stimulation or red irradiation. In contrast, pretreatment of the hypocotyl sections with low concentrations of boric acid before red irradiation or gravitational stimulation results in a rapid increase in fluorescein movement. Mung bean root tips without boron fail to remain attached to a negativelycharged glass surface after several minutes of red irradiation. A low boron concentration in the solution induces tip attachment. The suggestion is made that boron is required to stabilize a positive electrostatic charge in the plasma membrane that is generated by the actions of phytochrome and gravity.

Does cAMP Stimulate Nitrate Reductase Level in Fenugreek Cotyledons?

Summary There has been a claim in the literature that cAMP stimulates nitrate reductase level in mung bean roots. We have investigated this in fenugreek cotyledons (Trigonella foenum-graecum L.) where cyclic AMP stimulated nitrate reductase level in the cotyledons; however, other nucleotides, including AMP, also stimulated enzyme level suggesting that cAMP effect is probably unspecific.

Role of Membrane-bound, Fixed-charge Changes in Phytochrome-mediated Mung Bean Root Tip Adherence Phenomenon

The movement of cells and cell fragments in an electric field provided a means for determining the nature of cellular surface charges. We found that changes in ionic strength and particularly changes in Ca(2+) and H(+) in the bathing medium cause changes in the surface charges on the root cap cells in the absence of red light. Red light-induced charge changes are demonstrable only on root cap cells and are reversible with far red light. By osmotically separating the membrane from the wall, we demonstrated that both light-induced and ionically mediated charge changes are associated with the cell membrane and not the cell wall.

Veränderung im gehalt an ATP und ADP in wurzelspitzen der mungobohne nach hellrotbelichtung

Summary The content of ATP and ADP in mung bean root tips was determined after irradiation with red light for 4 minutes. Although the Tanada adhesion effect could be demonstrated we could not observe the immense decrease in ATP-content reported by Yunghans and Jaffe (1972). There was, in contrast, a slight but significant increase in ATP-level at constant energy charge. The results suggest that in mung bean root tips after absorption of red light by phytochrome the adenylate-system is as well regulated as in other living cells.

Effects of α-Hydroxysulphonate on Respiration of Mung Bean Root Tips

Effects of α-Hydroxysulphonate on Respiration of Mung Bean Root Tips

Changes in mitochondrial activity during enlargement of mung bean root cells

Changes in mitochondrial activity during enlargement of mung bean root cells

Cholinesterases from Plant Tissues

2-Isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride (AMO-1618) inhibits the activity of a cholinesterase isolated from mung bean (Phaseolus aureus) roots at concentrations comparable to those which retard growth and inhibit development of secondary roots of bean seedlings. Fifty per cent inhibition of the cholinesterase activity occurred at 0.21 mm. Inhibition of the cholinesterase is non-competitive and irreversible. The growth retardant seems to be a specific cholinesterase inhibitor since it has no effect on non-choline esterases.