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Abstract

Adventitious roots in mung bean [Vigna radiata (L.) R. Wilcz. cv. Berken] cuttings develop from specific “rooting-zone parenchyma” (R-ZP) cells. Microautoradiography was used to determine the timing of thymidine and uridine incorporation into the R-ZP cells, prior to the first cell division, in the presence or absence of naphthaleneacetic acid (NAA). Since 6-3H-thymidine incorporation reached a maximum between 11 and 14 hours, we suggest that the R-ZP cells were in the G1 phase when the cuttings were taken. Tritiated uridine was incorporated into the RNA of the R-ZP cells 2 hours after the cuttings were placed in the labeled solution. DNA synthesis and cell division of the R-ZP cells occurred along the entire length of the hypocotyl (basal, middle, and top segments), but these initial events were not sufficient to result in the subsequent formation of adventitious roots. NAA promoted adventitious root formation in the cuttings but it had no apparent effect on nucleic acid labeling nor initial cell division of the R-ZP cells. The initial division of the R-ZP cells appears to be a wounding response and occurs in the presence or absence of exogenous auxin.

Open Access

Abstract

Interspecific hybridization between Vigna radiata and V. angularis is reported for the first time. Two hybrids developed from embryos which were excised from immature seeds of V. radiata and cultured on artificial medium. The plants flowered early and continuously until death. No seeds were produced. Mean pairing at metaphase I was 2.39II + 17.22I (2n = 22).

Open Access

Abstract

Ethylene liberated from control and auxin-treated cuttings of Vigna radiata (L.) R. Wilcz cv. Berken was monitored for 14 hours. For root initiation, naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) were the most effective with indoleacetic acid (IAA) intermediate and 2,4-dichlorophenoxyacetic (2,4-D) the least effective. No correlation was observed between the quantity of auxin-induced ethylene evolved and the number of roots formed. Decreasing the NAA solution pH from 7.0 to 3.0 reduced the evolution of ethylene but did not alter the rooting response of the cuttings. It was concluded that stimulation of adventitious root initiation by auxin is not mediated by ethylene.

Open Access

Abstract

Adventitious root initiation decreased in ‘Berken’ mung bean cuttings treated with ≥ 10−4 m (2-chloroethyl) phosphonic acid (ethephon). Ethephon at 10−3 but not 10−5 m reduced root length and caused a redistribution of roots along the hypocotyl. The application of ethephon in combination with indoleacetic acid (IAA), indolebutyric acid (IBA), naphthaleneacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D) reduced root initiation. An initial treatment of ethephon followed by NAA, or NAA followed by ethephon, inhibited root initiation to the same degree. Ethephon—whether applied at the time of cutting preparation or up to 12 hours later—inhibited root initiation to the same extent.

Open Access
Authors: and

Seeds of `Berken' mung bean [Vigna radiata (L.) R. Wilcz.] were surface-sterilized with NaOCl and then either aerated 24 hours before sowing (routine procedure), planted immediately after the NaOCl treatment, or treated with hot cupric acetate and antibiotics before planting. Nine- or 10-day-old seedlings were used in rooting bioassays. Up to 10% of the seedlings and 17% of the cuttings had collapsed upper stems or wilted leaves. None of the seed treatments completely eliminated the pathogen, but the combination of hot cupric acetate plus antibiotics reduced the quantity of diseased cuttings to 3.3%. A white and two yellow-pigmented (Y1 and Y2) bacteria were isolated from diseased cuttings and used in subsequent pathogenicity tests. The Y2 strain was nonpathogenic. Stems of plants inoculated with the white strain turned brown and collapsed 2 days after inoculation, whereas leaves of plants inoculated with the Y1 strain wilted after 7 days. Electron microscopy, fatty acid analysis, and standard biochemical and physiological tests were used to identify the white strain as Pseudomonas syringae pv. syringae van Hall and the Y1 strain as Curtobacterium flaccumfaciens ssp. flaccumfaciens (Hedges) Collins and Jones. These results emphasize that seeds of mung bean should be checked for seedborne pathogens to avoid experimental artifacts.

Free access

Abstract

The performance of the mung bean cultivar Thai Green Oil was compared with the soybean cutivar Hsih-Hsih over a range of 12 plant densities from 10,000 to 800,000 plants/ha. Increasing plant density was positively related to yield and plant height and negatively related with significant reductions in flowering, yield per plant and plant branching. The higher yield potential of soybeans at high plant densities, relative to mung bean, was attributed to differences in the production of the number of flowers per plant and, subsequently, the number of pods per plant. This relationship can be applied to breeding and selecting improved mung bean cultivars.

Open Access

Adventitious root formation (rooting) in `Berken' mungbean [Vigna radiata (L.) Rwiclz.] cuttings is stimulated by indole-3-acetic acid (IAA). To understand the molecular events that occur during IAA-induced adventitious root initiation, a λgt11 cDNA library was made from mungbean hypocotyls treated with 500 μm IAA for 3 hours and differentially screened. Two cDNAs MII-3 and MII-4 were isolated. Southern analysis revealed that both cDNAs are encoded by different genes. Expression studies showed different patterns for both genes. Both MII-3 and MII-4 were highly expressed in IAA treated hypocotyls, whereas MII-4 was also induced in IAA treated epicotyls. There was no expression of either MII-3 or MII-4 in control or IAA treated leaves. With increasing concentrations of IAA from 100 to 1000 μm there was an increase in the average root number per cutting as well as a stimulation in MII-3 and MII-4. Both MII-3 and MII-4 showed a stimulation in expression 4 hours following treatment with 500 μm IAA reaching a maximum from 4 to 8 hours followed by a decline thereafter. Basal expression of MII-3 was evident between 2 and 8 hours, whereas, a high degree of basal expression was found with MII-4 from 1 to 8 hours followed by a sharp decline. Cycloheximide (50 μm) dramatically reduced rooting and MII-3 expression, whereas MII-4 was only slightly affected.

Free access

The effectiveness of using moving mean covariance analysis (MMCA) rather than randomized complete-block design (RCBD) in experimental error control was compared in a large-scale mungbean [Vigna radiata (L.) Wilczek] yield trial. The MMCA was superior to the RCBD, since it significantly reduced the experimental error and the coefficient of variation (cv). Inclusion of five neighboring plots in the moving mean computation provided better error control. However, the estimation of optimum number of neighboring plots to be used and moving mean calculations were tedious. The feasibility of using border-row measurements such as mean plant height at 50% flowering or mean seed yield/m of row as a covariate in an analysis of covariance (BRMCA) was examined in a separate mungbean yield trial in which border rows were planted with a check cultivar. Both border-row measurements were equally effective in reducing the experimental error. However, plant height measurements were simpler than measuring seed yield. Because border-row measurements could be readily used as covariate in analysis of covariance without a need for moving mean computation from the response variable, BRMCA could be advantageous for error control in row crops yield evaluation.

Free access

Tonoplast vesicles isolated from juice cells of mature `Valencia' oranges [Citrus sinensis (L.) Osbeck] showed similar tonoplast-bound vacuolar ATPase (V-ATPase) and inorganic pyrophosphatase (V-PPiase) activity as measured by product formation. Both proton pumps were able to generate a similar pH gradient, although steady-state was reached faster with ATP as substrate. When a ΔpH of 3 units was imposed (vesicle lumen pH of 4.5 and incubation medium of 7.5), tonoplast-bound PPiase was not able to significantly amplify the existing ΔpH. Although not able to function as a H+ pump, V-PPiase effectively synthesized PPi in the presence of inorganic phosphate (Pi). Formation of PPi by V-PPiase was enhanced by ATP but inhibited by NaF, gramicidin, and by antibodies raised against V-PPiase from mung bean [Vigna radiata (L.) R. Wilcz. (Syn. Phaseolus aureus Roxb.)]. Immunological analysis demonstrated an increase in V-PPiase protein with fruit maturity. Data indicate that under in vivo conditions, the V-PPiase of mature orange juice cells acts as a source of inorganic pyrophosphate (PPi) but not as a H+ pump. We propose that synthesis of PPi provides a mechanism for recovery of stored energy in the form of the pH gradient across the vacuole during later stages of development and postharvest storage.

Free access

Abstract

Selected putative inhibitors of ribonucleic acid (RNA) synthesis (actinomycin D and 6-methylpurine) or protein synthesis (cycloheximide and puromycin) were examined for their effects on root formation in mung bean (Vigna radiata (L.) R. Wilcz.) cuttings in the presence or absence of naphthaleneacetic acid (NAA). Only 6-methylpurine completely inhibited root formation at concentrations that did not cause visible injury. Cycloheximide was most inhibitory when applied at the same time as NAA. Application of 6-methylpurine up to 12 hours after NAA uptake completely blocked root formation; thereafter its effect declined with time. This decline in response was correlated with enlargement of the nucleus and nucleolus in hypocotyl cells preparatory to cell division.

Open Access