Indolylbutyric Acid Research Articles

Rapid propagation of agave by in vitro tissue culture

A procedure for rapid propagation of Agave (A. cantala Roxb., A. fourcroydes Lem. and A. sisalana Perrine, (Agavaceae) have been developed. The explants were excised from stolon plantlets, sterilized and cultivated on Murashige and Skoog (MS) basal medium containing 2% sucrose, 10% coconut water and 0.8% agar. The addition of following combination of growth substances—0.075 mgl-1 naphthalenacetic acid (NAA)+0.1 mgl-1 indolylbutyric acid (IBA)+0.5 mgl-1 kinetin (KIN) caused an extensive proliferation of multiple shoot primordia. Subcultures of these on the same medium were successful for the multiplication with an index of 3–4 times per 4 weeks subculture period. Shoots were rooted on hormone free MS medium and then transferred into a sand bed for acclimation before field planting.

Factors influencingin vitro micropropagation ofPinus strobus L.

Anin vitro procedure for micropropagation ofPinus strobus L., consisting of the following four steps has been established: shoot induction, shoot growth, root induction, and root growth. Influence of certain selected factors on each of these steps was determined. Shoot induction was found to be influenced by the age of the explant as well as the concentration of 6-benzyladenine in the medium. Best shoot growth was obtained on the medium of Litvayet al. without any growth regulators. Addition of activated charcoal to shoot growth medium resulted in fewer shoots. Root induction on several media was compared. Best root induction occurred when shoots were put on a half strength Gresshoff and Doy’s medium supplemented with 0.5 to 1.0 mg r1−1 α-naphthylacetic acid (NAA) for two weeks. Shorter exposure of shoots to higher concentrations of NAA or indol-3-ylbutyric acid (IBA) was not as effective. Low temperature seemed to be a requirement for root growth.

The fate of vitamin D3 and indolylbutyric acid applied to cuttings of Populus tremula L. during adventitious root formation

Abstract Treatment of green cuttings of Populus tremula L. with vitamin D3 enhances adventitious rooting and synergy is observed on simultaneous application with indolylbutyric acid. Translocation experiments with labelled vitamin D3 and IBA, fed to the base of the cuttings, showed that such synergy was not due to an effect of one substance on the translocation of the other. When indolylbutyric acid was fed to the base of the cuttings, a high proportion was rapidly converted into conjugates which, on saponifaction, released inter alia indolylbutyric acid, but no indolylacetic acid. On the other hand, vitamin D3 was metabolized to give products similar to those produced in non‐sterile aqueous solutions of vitamin D3 stored under the conditions of culture of the cuttings. Such a mixture is as effective as vitamin D3 itself in promoting adventitious rooting. A preliminary examination of the products showed that extensive oxidation of vitamin D3 had occurred and some of the individual components were synthesized and tested for their effect on rhizogenesis in P. tremula.

Effect of indol-3-ylbutyric acid, kinetin and gibberellic acid on alkaloid content inNicotiana rustica stem cuttings

The effect of the growth substances indol-3-ylbutyric acid (IBA), kinetin (Kn) and gibberellic acid (GA3) on the alkaloid content and recovery from the stress induced by removal of roots inNicotiana rustica L. plants have been studied. All treatments, mainly GA3, overcome the stress more effectively than the controls. The alkaloid content was increased 2.5fold with GA3. Treatment with Kn also increased the alkaloid content, but only in the absence of roots. In contrast, treatment with IBA slightly reduced the alkaloid content. The results of this investigation indicated that a degradation of stored alkaloids did not occur in spite of the stress.

Black rot of stentlings of roses: A disease caused by various soil fungi

Stenting is a technique for the production of genetically uniform plant material of roses. Stentlings, the young plants obtained by a combination of cutting and grafting, are susceptible to black rot of the rootstock. The first symptom is a dark discolouration of the rootless base of the rootstock. The disease is most harmful to newly made stentlings. It leads to complete deterioration of the stentling and can cause unacceptable losses. Leaf-bearing cuttings and older stentlings of which the rootstock and leaf-bearing scion have grown together were hardly affected by black rot, suggesting that assimilation products are necessary to confer resistance to the tissue. Treatment of the rootstocks with indolyl-butyric acid (IBA) in order to accelerate root formation promoted incidence of black rot. The increased incidence was not due to stimulation of mycelial growth of the pathogen by IBA. It is suggested that it may be attributed to an increased sensitivity of the rootstock caused by depletion of nutrients for expression of resistance. Several fungi were isolated from the diseased rootstocks. Isolates of the most common species were tested for their pathogenicity. Black rot was caused by 12 out of the 14 species tested. The most aggressive pathogens were Ceratobasidium sp., Coniothyrium fuckelii, Fusarium oxysporum, F. redolens, F. solani and Pythium ultimum. Moderately pathogenic were Alternaria alternata, Cylindrocladium parvum, Ophiostoma piceae and Gliocladium roseum. None of the three fungicides tested controlled the disease completely. Captafol, which has recently been withdrawn from the market, was by far the most effective one. Benomyl and, to a lesser extent, captan were effective during the first 5 days of incubation.

Improving rooting and survival of softwood peach cuttings

With leafy peach ( Prunus persica (L.) Batch) cuttings under mist, the highest rooting percentage, the largest number of roots per rooted cutting and the highest survival rates of the rooted cuttings were obtained by treating the bases of the cuttings for 24 h with a solution of 50 mg l −1 indolyl butyric acid (IBA) + 500 mg l −1 2,3-dichloro-1,4 naphthoquinone (dichlone). However, in the absence of dichlone, an IBA concentration of only 25 mg l −1 was optimal for rooting. Weekly sprays with a mixture of benzyladenine (BA) and naphthaleneacetic acid (NAA) increased the percentage of rooted cuttings in the poorly rooting cultivar ‘15–39’. Treatments to decrease the severe leaf-drop which occurred during the hardening-off period, i.e. weekly sprays with BA + NAA or with an anti-transpirant (TAG), if started at the beginning of the hardening-off period, considerably improved the survival of the rooted cuttings and their cytokinin content. Even more efficient in this respect were weekly sprays with a mixture of benzyladenine and myo-inositol, apparently due to an enhancement in the BA transport to the root system. This explanation is supported by the very marked accumulation of cytokinins in the roots of cuttings which had been sprayed with a mixture of myo-inositol and benzyladenine compared to plants which had been sprayed with benzyladenine alone. On the other hand, application of BA to leaves resulted in the inhibition of the transport of apically applied MI to the bases of the cuttings. Better leaf retention was related to increased levels of sugars in the cuttings. In the newly formed root system of the cuttings, a high cytokinin content was related to a high sugar content.

Adventitious root formation in green cuttings of Populus tremula: Characterisation of the effect of vitamin D3 and indolylbutyric acid

Indolyl‐3‐butyric acid and vitamin D3 enhance adventitious root formation in green cuttings of Populus tremula L. A significant synergistic effect is observed between these two substances. The number of roots formed on application of the individual substances and on simultaneous application depends on the growth substance concentration, the timing of application, the age of the cuttings and the number of leaves. Of the vitamin D3 animal metabolites tested, only 1,25‐dihydroxyvitamin D3 markedly promoted adventitious rooting, and this to a lesser extent than vitamin D3 itself. The 3‐O‐glucopyranosides of vitamin D3 and the vitamin D3 animal metabolites, promoted rooting to the same extent as the parent compounds.

Evidence for the presence of a native, non-auxinic rooting promoter in avocado (Persea americana Mill.)

The presence of a rooting promoter in paratially purified extracts of avocado (Persea amricana Mill.) organs has been demonstrated using the mung bean rooting bioassay. Extraction with 80% methanol was followed by partition into diethyl ether, paper chromatography (PC) and 3 steps of thin layer chromatography (TLC). The number of roots induced by the rooting promoter in the absence of exogenous auxin was 5 to 7 times higher than that of the water control and 50% higher than by 4-(indol-3-yl) butyric acid (IBA) at its reported optimum concentration. Rooting of tomato, Coleus and young avocado cuttings was also enhanced by the rooting promoter. The rooting promoter was inhibitory in the wheat coleoptile section elongation bioassay for auxins and had slight inhibitory activity in the split pea stem curvature test.

Auxin effects on rooting in pea cuttings

Light‐grown stem cuttingss of Pisum sativum L. cv. Weibull's Marma were rooted in a nutrient solution. The presence of 10 μM indolylacetic acid (IAA) in the solution for 24 h or longer periods decreased the number of roots subsequently formed to about 50% of control, provided IAA was present in the solution during any of the 4 first 24 h periods. Treatment for 6 h or shorter periods caused no or small response. IAA did not appreciably change the time needed for root formation, the time course of root appearance or the pattern of root distribution along the basal internode. IAA at 100 μM usually increased the number of roots although variable results were obtained with this IAA concentration.The number of roots was strongly increased by treatment with indolylbutyric acid (IBA) or 2,4‐dichlorophenoxyacetic acid (2,4‐D). None of these or other synthetic auxins decreased the number of roots in suboptimal concentrations. Experiments with 10 μM IBA showed that stimulation of rooting was obtained only if the auxin was present in the rooting solution for several days. Simultaneous treatment with IAA decreased the stimulating effect of IBA to some extent, whereas no such response was obtained if IAA was combined with 2,4‐D.IAA applied in lanolin to the stem of intact cuttings decreased the number of roots formed. Decapitation and debudding of the cuttings decreased the number of roots formed. If at least 2 leaves were left this decrease was efficiently counteracted by an optimal IAA dose applied to the upper part of the stem. A five times higher dose was less effective, indicating a negative effect on rooting also by IAA applied to the shoots.

Adventitious root formation ‘in vitro’ in apple rootstocks (Malus pumila) I. Factors affecting the length of the auxin‐sensitive phase in M.9

The length of the auxin‐sensitive phase of root initiation ‘in vitro’ in the apple rootstock M.9 (Malus pumila Mill.) has been determined using the auxins indol‐3yl‐acettc acid (IAA) at 2.8 × 10−5M and indol‐3yl‐butyric acid (IBA) at 1.5 × 10−5M in the presence and absence of 10−3M phloroglucinol (PG). PG synergised IBA‐induced rooting after 4 days exposure, but contact times exceeding 8 days decreased root number. In contrast, PG consistently synergised IAA‐induced rooting in the dark for contact periods up to 13 days with the highest rooting being recorded at 9 days. An irradiance of 20 W m−2 from fluorescent lamps halved IAA‐induced rooting irrespective of the presence or absence of PG. The culture of shoots at temperatures of 22,25 and 29°C during the root initiation phase (auxin present) and the root emergence phase (auxin absent) produced no difference in rooting response. In the presence of PG the use of liquid culture in place of agar‐solidified culture during the auxin‐sensitive phase reduced root number but not rooting percentage.

In vitro control of de novo flower differentiation from tobacco thin cell layers cultured on a liquid medium

Thin cell layers of tobacco (three to six layers of epidermal and subepidermal cells) were allowed to float on the surface of a liquid medium. Whereas the control on an identical medium solidified by agar gave 100% of explant‐forming flowers, no flowers formed in the absence of agar (100% of the explants formed buds). In order to initiate flower formation, various modifications of the liquid medium were tried: different ratios of indolyl‐3‐butyric acid (IBA) to kinetin (Kin) from 1 to 100, a range of pH from 4.0 to 7.0, and glass beads of different diameters (in an attempt to change the physico‐chemical characteristics of the culture substrate itself). On a liquid medium with glass beads, four types of morphogenesis (flowers, buds, a mixed programme of flowers and buds, and a non‐morphogenetic programme –i.e. the explants remained unchanged) were separately induced by changing one of the three factors: pH, IBA and Kin in equimolar concentrations, and diameter of the glass beads. Changing only the IBA/Kin ratio failed to provoke flower differentiation. pH of the medium was found to change after autoclaving and the effect of glass beads on morphogenesis was partly related to modification of pH.

The Apparent Involvement of Polyphenol Oxidase and Phloridzin in the Production of Apple Rooting Cofactors

SummaryPolyphenol oxidase (PPO) activity and phloridzin content in vacuum-extracted xylem sap of M.26 apple cuttings increased between mid-December and late January, preceding an increase in endogenous rooting cofactor activity and the rooting of cuttings between late January and mid-February 1979. When tested by the mung bean bioassay in the presence of indolylbutyric acid (IBA) many phenolic substances improved rooting, especially oxidized forms and derivatives. The product of a reaction between polyphenol oxidase (PPO) and phloridzin in vitro was markedly active in the mung bean test and showed certain similarities with the extracted endogenous cofactor following chromatography. The cofactor activity of sap extracted during the period of poor rooting in midwinter was increased by adding both PPO and phloridzin and the rooting of IBA-treated cuttings was increased by pre-treatment with the products of a PPO and phloridzin reaction.

Micropropagation of red raspberry and the influence of phloroglucinol

Micropropagation of 12 raspberry seedling selections and the cultivar ‘Malling Jewel’ has been achieved. A basic culture medium (Linsmaier and Skoog, 1965) supplemented with benzylaminopurine (BAP), 1.0 mg l −1, and indol-3-yl butyric acid (IBA), 0.1 mg l −1, was optimal for shoot proliferation. The presence of phloroglucinol (PG) at a concentration of 162 mg l −1 significantly increased shoot number at all auxin: cytokinin concentrations. Removal of the cytokinin and increasing the concentration of IBA to 1.0 mg l −1 resulted in adventitious root formation. PG synergistically promoted the number of roots per rooted culture but did not significantly increase the percentage rooting. Viable plants were produced from all genotypes when transplanted to soil.

Effect of nitrogen nutrition of stock plants ofJusticia gendarussaL. on the rooting of cuttings

SummaryThe effect of the nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings was studied in sand culture under high, medium and low levels of nitrogen.Nitrogen starvation induced rooting. Exogenous application of the auxins IAA (indol-3yl-acetic acid), IBA (indol-3yl-butyric acid) and NAA (naphth-lyl-acetic acid) greatly increased the rooting response of cuttings from-stock plants grown with small amounts of nitrogen.The root-promoting effect of a low nitrogen supply was associated with a retardation of growth in the stock plants from which the cuttings were made. High C/N (total available carbohydrates/total nitrogen) and P/N (total phosphorus/total nitrogen) ratios increased anthocyanin pigmentation in the shoot, and increased rooting cofactor activity in the tissues of cuttings. The phenolic compounds, ferulic acid, p-hydroxybenzoic acid and p-coumaric acid were present in the shoots of all three nutritional treatments and acted as important cofactors in the cuttings. In general, rooting cofactor activity was inversely related to nitrogen supply and the activity was highest under low nitrogen.The cuttings taken from plants grown under different levels of nitrogen interacted differentially with the exogenously applied auxins.

Early Responses of Excised Stem Segments to Auxins

The elongation rate of lupin hypocotyl and pea stem segments was measured every minute after the addition of various auxins and auxin precursors. After a latent period the growth rate increased to a peak, fell to a minimum, and with most compounds increased to a second maximum. Compounds used include indol-3yl-acetic acid (IAA), indol-3yl-acetamide, naphth-2yl-oxyacetic acid, naphth- lyl-acetamide, and indol-3yl butyric acid. The extensibility of the cell walls of the lupin segments was measured with an Instron Universal Testing Instrument at intervals after the addition of IAA and it was shown that the lag period before the extensibility increased was longer than that for the growth-rate. Kinetic studies were made of the effect of Actinomycin I) on IAA-induced growth. KNA synthesis during the first 20 and 40 min after IAA addition was also examined in segments exposed to labelled RNA precursors during these times. The results support the conclusion that RNA synthesis is not necessary for the initial action of auxin on elongation.

ROOTING OF HARDWOOD CUTTINGS IN RELATION TO BUD DORMANCY AND THE AUXIN CONTENT OF THE EXCISED STEMS

SummaryExperimental evidence is given for poplar cuttings (Populus x robusta Schneid.) of the role of dormant and nondormant buds to root initiation. Chilling treatments shortened bud dormancy and greatly increased the emergence of pre‐formed roots from stem cuttings, but caused a smaller increase in numbers of wound‐roots. With terminal popular cuttings greater root numbers were obtained when, after excision, a warm treatment preceded chilling. Chilling only induced a large increase in the number of wound‐roots on terminal apple cuttings (Malus cv. Mailing II), if steeped in indolyl butyric acid immediately after the chilling treatment.A greater amount of auxin was found in chilled than in unchilled poplar cuttings five weeks after the end of chilling.Endogenous auxin levels at the base of both intact and disbudded, chilled cuttings of poplar were high at the time when roots were about to emerge from the cortex, but were low 15 days later when the roots were several centimetres in length.

Effect of Position of IBA Application on the Rooting of Plum Hardwood Cuttings

SummaryThe rooting ability of plum rootstock hardwood cuttings inserted for one month in a peat-grit medium at 70 °F basal temperature was influenced by the depth to which they were previously dipped in an alcoholic solution of 4(indolyl-3) butyric acid (IBA). Although in detail the response varied with IBA concentration and rootstock clone, in general the highest proportion of cuttings rooted when only the basal cut end of the shoot was treated. The detrimental effect of dipping to one inch increased with increasing concentration of IBA and was shown to be caused by the application of IBA to the epidermis, since it could be eliminated by sealing the epidermis with polyvinyl resin prior to dipping or by reducing the concentration of IBA applied to the epidermis relative to that applied to the cut end. Epidermal application was only beneficial when insufficient stimulation to rooting was obtained through basally-applied IBA.

Factors affecting the rooting of plum hardwood cuttings

SummaryOptimum conditions for rooting hardwood cuttings of several plum rootstocks have been determined with respect to season of cutting collection, the thickness of shoot and the part of the shoot used as the cutting, the concentration of rooting hormone applied to the base of the cutting and the basal temperature in the rooting medium.Rooting occurred most readily during autumn and again in late winter and spring. Cuttings made from “thin” shoots generally rooted more readily than those from “thick” ones but the position along the shoot from which the cutting was made was usually unimportant.Some clones, including Myrobalan B and St. Julien A, responded to increasing concentrations of 4(indolyl-3) butyric acid (IBA) to an optimum at 5,000 p.p.m. and to increasing bottom heat to about 20° C. Others, including Brompton and Pershore, were relatively unresponsive to both of these factors under the conditions of these experiments.

The Influence Of4(Indolyl-3) Butyric Acid and Basal Temperature on the Rooting of Apple Rootstock Hardwood Cuttings

SummaryPre-rooting treatment with auxin, and the temperature of the rooting medium, were found to operate independently in promoting rooting of Crab C and M.26 hardwood cuttings.Rooting in terms of percentage rooted cuttings, number of roots per cutting and dry weight of root system, improved with increasing concentration of 4(indolyl-3) butyric acid (IBA) to an optimum, which differed for the various measurements and for rootstock variety, but which was at or above 1,250 p.p.m. There was a tendency for the optimum concentration for rooting percentage to be lower than that for root numbers and, with Crab C, the increase in number of roots was associated with a reduction in the dry weight of individual roots. M.26 showed no such trend.Temperature of the rooting medium, within the range 50°-82° F. (10°-28° C.), also had a marked effect upon rooting, with the optimum occurring at or above 72· F. (22· C.), and, as with IBA concentration, the higher temperatures of about 8o° F. (27° C.) favouring root numbers ...

Rooting of Cuttings of Acer Rubrum l. And Eucalyptus Camaldulensis Dehn.

Rooting of cuttings of A. rubrum and E. camaldulensis taken from seedlings grown under controlled conditions was stimulated by auxin treatments. Indolylbutyric acid at a concentration of 1�0 mgjl was the optimal auxin treatment. Rooting of cuttings was affected by the light conditions under which seedlings were grown.