Rooting Of Mung Bean Cuttings Research Articles

Ethylene and rooting of mung bean cuttings. The role of auxin induced ethylene synthesis and phase-dependent effects

We have re-examined the role of ethylene during rooting of mung bean cuttings. Cuttings were treated for 5 days with a low or a high concentration of NAA (naphthaleneacetic acid). During this 5 days period, we also applied STS (silverthiosulfate, an inhibitor of ethylene action) or ACC (1-aminocyclo-propane-l-carboxylic acid, a direct precursor of ethylene). At high NAA concentration, STS promoted and ACC inhibited rooting, respectively. At low NAA concentration, the effects were opposite, STS being inhibitory and ACC promotive. AVG (aminoethoxyvinylglycine, an inhibitor of ethylene synthesis) gave similar results as STS. Together, these data suggest supraoptimal and suboptimal ethylene levels in the tissue at high and low NAA concentration, respectively. We also examined whether the effect of ethylene varied during the successive phases of the rooting process. Thus, we gave 24 h pulses with either STS or ACC during the rooting treatment. During the first two days (0–48 h), ACC-pulses were promotive and STS-pulses inhibitory. Later on (48–168 h), the ACC-pulses were inhibitory and the STS-pulses promotive. Whether this effect was observed or not was dependent on the NAA concentration. These data indicate that ethylene promotes or inhibits rooting depending on the stage in the rooting process. When ACC was added only during the initial period, rooting was increased at all NAA concentrations in a NAA dose-response curve and the optimal NAA concentration remained the same. This suggests that ethylene renders more cells responsive to NAA.

Role of Auxin and Polyamines in Adventitious Root Formation in Relation to Changes in Compounds Involved in Rooting

An attempt was made to identify some cellular components that control adventitious root formation at the base of hypocotyl cuttings of mung bean (Vigna radiata L. cv. 105). Three phases of the adventitious root formation process were identified; induction (0-24 h), initiation (24-72 h), and expression (after 72 h). The lower peroxidase activity during the induction period (0-24 h) corresponded with the first peak of IAA at 24 h which indicated termination of the induction phase. A peak of peroxidase activity with low IAA levels at 72 h signaled the termination of the initiation phase. After 72 h, peroxidase activity declined and IAA levels increased slowly and this was characterized as the expression phase. IAA-oxidase activity could be inversely correlated with endogenous IAA levels. Endogenous putrescine and IAA increased simultaneously both at the induction and initiation phase, and might have a combined role in adventitious root formation. Spermidine and spermine levels did not change significantly throughout these phases. The pattern of diamine oxidase and polyamine oxidase (DAO/PAO) activities was inversely correlated with endogenous polyamine levels only during the induction phase. Levels of H 2 O 2 , which is involved in IAA and phenol oxidation and also in cell wall xylogenesis, were positively correlated with DAO/PAO activity because H 2 O 2 is one of the end products of PA oxidation. An inverse relationship between phenol content and polyphenol oxidase activity was observed during rooting of mung bean cuttings. Compared with controls, IBA-(10 -5 M) or PUT-(10 -4 M) treated cuttings exhibited increased levels of IAA, putrescine, phenol and H 2 O 2 , decreased IAA-oxidase activity, and increased DAO/PAO, peroxidase, and polyphenol oxidase activities. An early appearance of the second peak of putrescine and phenol at the end of the initiation phase (72 h) was observed in cuttings treated with IBA or PUT. On the basis of IAA levels and peroxidase activity, there was no change in the duration of different rooting phases due to IBA or PUT treatments. However, on the basis of endogenous PUT levels, treatment with IBA or PUT reduced the total duration of the initiation and expression phases.

Effect of Wild-Type and Mutant Plant Growth-Promoting Rhizobacteria on the Rooting of Mung Bean Cuttings.

Mung bean cuttings were dipped in solutions of wild type and mutant forms of the plant growth-promoting rhizobacterium Pseudomonas putida GR12-2 and then incubated for several days until roots formed. The bacteria P. putida GR12-2 and P. putida GR12-2/aux1 mutant do not produce detectable levels of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, whereas P. putida GR12-2/acd36 is an ACC deaminase minus mutant. All bacteria produce the phytohormone indole-3-acetic acid (IAA), and P. putida GR12-2/aux1 overproduces it. Treatment of cuttings with the above-mentioned bacteria affected the rates of ethylene production in the cuttings in a way that can be explained by the combined effects of the activity of ACC deaminase localized in the bacteria and bacterial produced IAA. P. putida GR12-2 and P. putida GR12-2/acd36-treated cuttings had a significantly higher number of roots compared with cuttings rooted in water. In addition, the wild type influenced the development of longer roots. P. putida GR12-2/aux1 stimulated the highest rates of ethylene production but did not influence the number of roots. These results are consistent with the notion that ethylene is involved in the initiation and elongation of adventitious roots in mung bean cuttings.

Interaction of paclobutrazol and indole‐3‐butyric acid in relation to rooting of mung bean (Vigna radiata) cuttings

Paclobutrazol (PB) only slightly stimulated the rooting of mung bean cuttings but, interestingly, the number of adventitious roots formed was dramatically increased when PB was used together with indole‐3‐butyric acid (IBA). Application of PB in the first phase of root formation, when root initials are induced, caused the greatest enhancement of the promotive effect of IBA on rooting. Investigation of the effect of PB on uptake, transport and metabolism of [5‐3H]‐IBA in mung bean cuttings revealed some changes in the rate of metabolism of IBA in comparison with control cuttings. PB was found to be involved in the partitioning of carbohydrates along the cuttings. Application of sucrose, like PB to the base of IBA‐treated cuttings enhanced the effect of IBA. The patterns of the effects of PB and IBA, separately and together, on rooting were similar in defoliated and intact cuttings, however the number of roots was much lower in the defoliated cuttings, which lacked a source of assimilates. PB counteracted the effect of GA3 in the upper regions of the cuttings and seemed to increase the sink capacity at the base of the cuttings. The results of the present study clearly demonstrated the enhancing influence of PB on IBA stimulation of the rooting of mung bean cuttings. It is suggested that PB may affect the rate of metabolism of IBA during rooting and the status of the local sink, in the base of the cuttings, thus partially contributing to the enhancement of the rooting‐promotive effect of IBA.

Indo-3-acetic acid (IAA) and cytokinin-like activity in municipal excess activated sewage sludge: effect on rooting of mung bean (Vigna radiata (L.) Wilcz.) cuttings

Abstract A common use for land treatment of municipal sewage sludges is their application in agriculture. Sludges are well known to contain high levels of organic and inorganic materials but can also affect plant growth by supplying growth hormones. We tested the hormonal effect of sewage sludge from the Municipal Sewage Sludge Management Center in Herzliyya, Israel, on rooting of mung bean cuttings. Sewage sludge induces the formation of adventitious roots on mung bean cuttings, in a way similar to the promotion by IBA, the most common treatment for root initiation. Moreover, sewage sludge quadrupled the root elongation rates as compared with the effect of IBA and it seems that at least Herzelia source of municipal se~age sludge comprises a very promotive growth medium for root development. Significant amount of IAA was identified in sewage sludge by GC-MS. The sludge exhibits also cytokinin-like activity. The data of this study and particularly the effect of the sludge on the development of the adventit...

Effects of fermented cow‐manure on rooting of mung bean cuttings: The role of nutrients and of abscisic acid

Abstract The effects of cabutz, an end product of anaerobic fermentation of cow manure, and the effects of its components, on rooting of cuttings were investigated. Cuttings of mung bean (Vigna radiata L. Wilcz.) plants have rooted better in cabutz than in other rooting media. Cabutz extract increased the number of roots of mung bean cuttings as well as their roots length. Similar effects were obtained with a solution containing only the inorganic constituents of cabutz extracts. The complete cabutz extract, but not its mineral components, caused three pronounced effects: (a) it changed the distribution pattern of adventitious roots along the cuttings; (b) it delayed the initiation of roots at the base of the cuttings in the presence of high concentrations of cabutz extract; and (c) it reduced the water loss by cabutz‐treated cuttings. Similar effects were obtained when external abscisic acid was applied in concentrations similar to what was found in cabutz extracts. It is suggested that the effects of ca...

ETHIDIUM BROMIDE INHIBITION OF NAA-INDUCED ROOTING IN MUNG BEAN CUTTINGS

Ethidium bromide (EB), at 10-5 to 10-4 M, progressively inhibits NAA-induced rooting of mung bean cuttings. Cycloheximide (CH), 6-methylpurine (6-MP) and kinetin (KIN) also inhibited rooting at the same concentrations, although CH and 6-MP were more effective. At 70 and up to 130 hours of incubation, after cuttings received a 1-ml pulse of NAA (10-4 M), they exhibited a progressive increase in the number of observed adventitious roots. The addition of one of the inhibitors, 6-MP, EB or KIN to cuttings, pulsed 48 hours earlier with NAA, showed an initial slight inhibition with increased inhibition over time. CH, however, inhibited rooting immediately after addition. From these and other similar kinetic studies, it appears that 6-MP, EB and KIN operate at the transcriptional level and that CH inhibits translation. Lineweaver-Burk plot analysis of NAA-induced rooting inhibition showed that EB may act as a competitive inhibitor of NAA. Since EB is a known intercalating agent and competitively inhibits NAA-induced rooting, NAA may influence gene expression by ultimately binding to DNA. Studies with space-filling and computer-generated models show that both NAA and EB can bind to certain dinucleotides by an intercalation mechanism.

Characterization and Rooting Ability of Indole-3-Butyric Acid Conjugates Formed during Rooting of Mung Bean Cuttings

Indole-3-butyric acid (IBA) is rapidly metabolized by mung bean cuttings during rooting. Twenty-four hours after application, less than 20% of the applied IBA remained in the free form and its level decreased continuously in the later stages of rooting. Indole-3-butyrylaspartic acid (IBAsp) and at least two high molecular weight conjugates were the major metabolites in IBA-treated cuttings. In the latter conjugates, at least part of the IBA moiety is attached to a high molecular weight constituent in an amide linkage. IBAsp level peaked 24 hours after application of IBA to the cuttings and then declined. The level of the high molecular weight conjugates increased continuously throughout the rooting process. The conjugates were active in inducing rooting of cuttings, with IBAsp being superior to free IBA. It is suggested that IBA conjugates, and particularly IBAsp, serve as the source of auxin during the later stages of rooting.

The interaction of prechilling and ACC and the stimulation of rooting of mung bean cuttings and intact hypocotyls

The induction of adventitious roots on intact hypocotyls of mung bean ( Vigna radiata (L.) R. Wilcz. cultivar ‘Berken’), growing on their stock plants, was increased substantially following pretreatment of stock plants with low temperature (15°C) for up to 27 days, before treatment with indolebutyric acid (IBA). The rate of root initiation and final root numbers were further increased by concurrent treatment with 1-aminocyclopropane-1-carboxylic acid (ACC). A similar but greater response to prechilling was observed when cuttings were taken from prechilled plants and incubated with IBA. Prechilling and IBA produced their effects on rooting independently of one another, and it was suggested that prechilling increased the sensitivity of mung bean hypocotyl tissue to auxin.

Root Regeneration, Starch Content, and Root Promoting Activity in Tilia cordata Cultivars at Three Different Digging-Planting Times

Three-year-old, 250 cm (8 ft) bareroot-dug Tilia cordata cultivars were planted at three different digging-planting times: (1) fall-dug and fall-planted, (2) fall-dug and spring-planted following winter storage, and (3) spring-dug and spring-planted. Fall-dug, fall-planted trees had a significantly higher number of new roots initiated than trees from either of the other two digging-planting times. Differences in root starch content were not significant enough to account for the reduced amounts of root regeneration in the two spring-planted groups. Extracts from cut root tips of spring-dug, spring-planted trees had the greatest ability to promote rooting of mung bean cuttings. This result did not correspond to the actual field performance of the trees. Other factors that may have influenced the root regeneration of spring-planted trees are discussed.

Quinones as plant growth regulators

The effects of benzoquinone, naphthaquinone and anthraquinone on the growth of tomato callus, whole plants of tomato and on rooting of mungbean cuttings were studied. Naphthaquinone effects on some oxidases and on the isozyme patterns of peroxidases in all the three systems were also observed. Quinones increased callus growth, the number of roots initiated in mungbean cuttings and the growth of tomato plants, significant increases being obtained with 10−5M naphthaquinone. Naththaquinone also decreased the activities of IAA oxidase, ascorbic acid oxidase and polyphenol oxidase, and led to the disappearance of one of the isozyme of peroxidase in all systems.

Effect of Ethephon, Indole Butyric Acid, and Treatment Solution pH on Rooting and on Ethylene Levels within Mung Bean Cuttings

Light-grown mung bean (Phaseolus aureus Roxb.) cuttings were treated with buffered and nonbuffered solutions of Ethephon, indole butyric acid (IBA), and the combination of both. Ethephon treatment resulted in increased tissue ethylene levels with increasing solution pH, but had no effect on rooting. IBA treatment had no effect on tissue ethylene levels, but strongly promoted rooting. Combinations of Ethephon and IBA had no effect on rooting of mung bean cuttings beyond that obtained by IBA alone.

Promotion of Rooting of Mung Bean Cuttings by Dihydroasparagusic Acid Synergistic Interaction with Indoleacetic Acid

Summary Dihydroasparagusic acid (β,β’-dithiolisobutyric acid) increased the number of roots formed on mung bean hypocotyl segments under continuous illumination. Longer initial treatment did not affect root number, but did decrease root elongation. Dihydroasparagusic acid in combination with indoleacetic acid synergistically increased root number, but not root elongation.

Diffusible Rooting Substances in Woody Ornamentals1

Abstract Water soluble rooting substances were obtained from selected woody ornamentals by the centrifugal diffusion method from the cuttings, or by the water extraction method from the ground freeze-dried cuttings. Species used were Cotoneaster racemiflora soongorica, Euonymus fortunei carrierei, Ilex opaca, Lonicera maacki, Physocarpus amurensis, Symplocos paniculata, Taxus cuspidata, Viburnum burkwoodi, and V. opulus. The centrifugal diffusates from Cotoneaster racemiflora soongorica, Euonymus fortunei carrierei, and Symplocos paniculata promoted rooting of mung bean cuttings. Generally the centrifugal diffusates from all of the species studied contained 4 root-promoting fractions with Rf’s, in isopropanol:ammonia:water, of 0–0.1, 0.2–0.4, 0.6–0.8, and 0.8–1.0. All of these fractions promoted rooting of mung bean cuttings without added indole-3-acetic acid. The fraction at Rf 0-0.1 caused the strongest root promotion. Similar results were found in the water extract from the freeze-dried materials. The results strongly suggest that diffusible and water-soluble rooting substances commonly exist among many species of woody plants.

Root‐promoting Substances in Salix alba

AbstractRoot‐promoting substances were extracted from softwood cuttings of Salix alba L. by centrifuging them with water or by shaking the ground freeze‐dried stems with water. Rooting substances were partitioned by paper chromatography or chemical fractionation and their rooting activity was tested by mung bean cuttings. Both extracts indicated three major root ‐promoting fractions at Rf 0‐0.1, 0.7‐0.8, and 0.3‐0.4 in a decreasing order of their activities when paper chromatographed with isopropanol:ammonia:water 8:1:1 v/v. The strongest one indicated an apparent synergistic rooting effect with indol‐3yl‐acetic acid (IAA) regardless of the extraction method. These results indicate that water can extract from freeze ‐dried sample the similar rooting substances found in the centrifugal diffusates. The Rf 0–0.1 fraction consisted of at least four fractions and the strongest one did not move from the starting line on the chromatogram when isopropanol:ammonia:water 8:1:1 was used. This starting line fraction was extremely strong in rooting activity and its highest concentration resulted in 8.7 times as many roots as controls. More thain additive rooting effect between IAA and the fraction was found only at the highest concentration. The fraction was very soluble in water but insoluble in chloroform or ethyl ether and only stimulated rooting of mung bean cuttings when it was applied within 3 days after cuttings were made. It had no effect in lengthening roots. The starting line fraction was further found to have four root‐promoting subfractions at Rf 0.05, 0.35, 0.65, and 0.85 when it was chromatographed in 60 % isopropanol. Among these four, the subfractions at Rf 0.65 and 0.35 were strongly root promotive and displayed more than additive root promotion with IAA at the highest concentrations studied.