Treatment of bean cuttings by chestnut extracts during rooting modifies their IAA-oxidase activity

The IAA-oxidase activity in bean cuttings ( Phaseolus vulgaris L. cv. Contender) treated with extracts from juvenile and adult chestnut ( Castanea sativa Mill.) was studied in the light of the effect of the extracts on the rooting activity of some auxins. Extracts from adult chestnut increased IAA-oxidase activity in bean cuttings. Extracts from juvenile chestnut inhibited IAA-oxidase activity only slightly, but substantially reduced the IAA-oxidase activity of bean cuttings pre-treated with adult chestnut extracts. These findings provide evidence that there is a relationship between the IAA-oxidase system and the effect of chestnut extracts on IAA-induced rhizogenesis in bean cuttings.     

Comparison of movement and metabolism of indole-3-acetic acid and indole-3-butyric acid in mung bean cuttings

Indole-3-butyric acid (IBA) was much more effective than indole-3-acetic acid (IAA) in inducing adventitious root formation in mung bean ( Vigna radiata L.) cuttings. Prolonging the duration of treatment with both auxins from 24 to 96 h significantly increased the number of roots formed. Labelled IAA and IBA applied to the basal cut surface of the cuttings were transported acropetally. With both auxins, most radioactivity was detected in the hypocotyl, where roots were formed, but relatively more IBA was found in the upper sections of the cuttings. The rate of metabolism of IAA and IBA in these cuttings was similar. Both auxins were metabolized very rapidly and 24 h after application only a small fraction of the radioactivity corresponded to the free auxins. Hydrolysis with 7 M NaOH indicates that conjugation is the major pathway of IAA and IBA metabolism in mung bean tissues. The major conjugate of IAA was identified tentatively as indole-3-acetylaspartic acid, whereas IBA formed at least two major conjugates. The data indicate that the higher root-promoting activity of IBA was not due to a different transport pattern and/or a different rate of conjugation. It is suggested that the IBA conjugates may be a better source of free auxin than those of IAA and this may explain the higher activity of IBA.     

Methyl gallate and its 3-glucoside promote rooting in bean cuttings

Methyl gallate stimulated adventitious root formation in cuttings of bean (Phaseolus vulgaris L.). This polyphenol was quickly metabolized into 3-glucosyl methyl gallate to such an extent that 4 h after application no methyl gallate was detected. The isolated glucoside when supplied exogenously at 0.5 mM also enhanced rooting; the effect was 2-fold greater than that of methyl gallate. The glucoside persisted in the cuttings for 72 h after treatment. Because methyl gallate is rapidly transformed to a stable glucoside, we suggest that the root stimulation effect could be ascribed to its glucoside.     

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.     

Triadimefon stimulates rooting in bean hypocotyl

Triadimefon, a broad spectrum fungicide and an inhibitor of gibberellic biosynthesis, whitened, thickened, and shortened the roots of bean ( Phaseolus vulgaris L. cv. Spring Green) seedlings and stimulated the development of root primordia along the hypocotyl. In a comparative study, triadimefon, IAA, spermidine, putrescine and spermine all stimulated adventitious root growth, but triadimefon was more effective than the other 4 compounds. Equimolar concentrations of gibberellic acid (GA₃) completely eliminated the stimulatory effect of triadimefon. Stimulation of root development by triadimefon was accompanied by inhibition of ethylene biosynthesis followed by removal of basal dominance and an increase in polyamine levels, both of which occurred after rooting had begun. Although triadimefon was effective in stimulating rooting, its mechanism of action is apparently not mediated via the control of ethylene and polyamine biosynthesis.     

The effect of indole-3-acetylaspartic acid on adventitious root formation on bean cuttings

The influence of indole-3-acetylaspartic acid (IAAsp) on rooting of stem cuttings from bean plants (Phaseolus vulgaris L.) of different ages, cultivated at different temperatures (17°, 21° and 25°C) was studied and compared to that of indole-3-acetic acid (IAA). At a concentration of 10^–4 M, IAAsp only nonsignificantly stimulated adventitious root formation, approximately to the same level as IAA in all treatments. IAAsp at 5×10^–4 M further enhanced rooting, by up 200% of control values, with little influence of temperature conditions and stock plant age. This concentration of IAA usually stimulated rooting more than the conjugate. The largest differences between the effects of IAAsp and IAA occured at the highest cultivation temperature of 25°C where stock plant age also influenced the response. The number of roots produced in comparison with the control, was enhanced from 350% on cuttings from the youngest plants to more than 600% on cuttings from the oldest. In contrast to the conjugate, 5×10^–4 M IAA induced hypocotyl swelling and injury of the epidermis at the base of cuttings, in all treatments.     

Diheteroarylurea derivatives as adventitious rooting adjuvants in mung bean shoots and M26 apple rootstock

The present research investigates the biological profile of eight symmetrical diheteroarylureas and phenylheteroarylureas, testing their hypothetical cytokinin-like activity and rooting activity. Cytokinin-like activity was assayed by the betacyanin (so-called amaranthin) accumulation test and by the tomato regeneration test. The rooting activity was assessed using the mung bean rooting test, the apple stem slice test and the rooting of apple microcuttings. Three compounds, 1,3-di(pyrazin-2-yl)urea (3a), 1,3-di(benzo[d]oxazol-5-yl)urea (3b) and 1,3-di(benzo[d]oxazol-6-yl)urea (3c), enhanced adventitious root formation in apple stem slice test, but only 3b and 3c were active in the mung bean rooting test. Compound 3b, that showed the best rooting activity, was also able to enhance the adventitious root formation in apple microcuttings. None of the compounds showed cytokinin-like activity.     

Levels of endogenous indole-3-acetic acid and indole-3-acetylaspartic acid during adventitious root formation in pea cuttings

Levels of endogenous indole-3-acetic acid (IAA) and indole-3-acetylaspartic acid (IAAsp) were monitored in various parts of leafy cuttings of pea ( Pisum sativum L. cv. Marma) during the course of adventitious root formation. IAA and IAAsp were identified by combined gas chromatography—mass spectrometry, and the quantitations were performed by means of high performance liquid chromatography with spectrofluorometric detection. IAA levels in the root forming tissue of the stem base, the upper part of the stem base (where no roots were formed), and the shoot apex remained constant during the period studied and were similar to levels occurring in the intact seedling. A reduction of the IAA level in the root regenerating zone, achieved by removing the shoot apex, resulted in almost complete inhibition of root formation. The IAAsp level in the shoot apex also remained constant, whereas in the stem base it increased 6-fold during the first 3 days. These results show that root initiation may occur without increased IAA levels in the root regenerating zone. It is concluded that the steady-state concentration is maintained by basipetal IAA transport from the shoot apex and by conjugation of excessive IAA with aspartic acid, thereby preventing accumulation of IAA in the tissue.     

Interaction of ethylene with indole-3-acetic acid in regulation of rooting in pea cuttings

Cuttings of pea (Pisum sativum L. cv Marma) were treated with 1-aminocyclopropane-l-carboxylic acid (ACC). This treatment caused increased ethylene production and reduction of root formation. The effect of 0.1 mM ACC on the level of endogenous indole-3-acetic acid (IAA) in the rooting zone and in the shoot apex was analyzed by gas chromatography-single ion monitoring mass spectrometry or by high pressure liquid chromatography with fluorimetric detection (HPLC). Concentrations of indole-3-acetylaspartic acid (IAAsp) in the stem bases were also determined using HPLC. The ACC treatment had little effect on the IAA level in the base measured after 24 h, but caused a considerable decrease during the 3 following days. IAAsp increased in the base on days 1, 2 and 3 and then declined. The build up of IAAsp in the base was not affected by ACC during the first two days of the treatment, but later this conjugate decreased more rapidly than in controls. No effect of the ACC treatment was found on the level of IAA in the apex. IAA (1 µM) applied to the cuttings during 24 h reduced the number of roots formed. The possibility that IAA-induced ethylene is involved in this response was investigated.Our results support earlier evidence that the inhibitory effect of ethylene on rooting in pea cuttings is due to decreased IAA levels in the rooting zone. The inhibitory effect of applied IAA is obtained if the internal IAA level is maintained high during the first 24 h, whereas stimulation of rooting occurs if the internal IAA level remains high during an extended period of time. Our results do not support the suggestion that ethylene mediates the inhibitory effect of applied IAA.     

Influence of ethylene on adventitious root formation in mung bean hypocotyl cuttings

The relationship between ethylene and adventitious root formation in mung bean hypocotyl cuttings was studied.Ethephon, an ethylene-releasing compound, at 5 x 10 -5 M increased root number and root dry weight on hypo-cotyl cuttings. When ethephon was applied to hypocotyl at different times after excision, there were two effectivetimes for root production i.e. between 06 h and 18-24 h. These two time periods correspond to the induction phase and the late initiation phase of root development, respectively. After excision, three peaks of ethylene productionwere observed. The first peak commencing at 6 h started the sequence of reactions leading root formation, the second peak appearing at 12 h coincided with the beginning of the increase of the IAA level during primordia initiation, and the third peak showing at 48 h played a role in root differentiation and growth. Ethylene stimulated rooting by enhancing the increase in auxins. Thus it appears that the IAA-induced ethylene production may be a factor involved in the stimulation of adventitious root formation.     

NAA处理桉树插条后IAAO活性与生根的关系

尾叶桉MLA无性系(简称MLA)为难生根植物,尾叶桉U₆无性系(简称U₆)和刚果12号桉W₅无性系(简称W₅)为相对易生根植物。MLA插条内的吲哚乙酸氧化酶(IAAO)活性较U₆、W₅的高。用萘乙酸(NAA)处理桉树插条后,在扦插生根的不同阶段,插条内IAAO活性呈现规律性变化;可溶性蛋白质含量呈上升趋势。本文讨论了IAAO与桉树插条生根的关系。     

甘蔗废糖蜜对绿豆插条下胚轴生根的影响

本文研究甘蔗废糖蜜对绿豆插条下胚轴生根的影响,结果表明,1000~7000mg/L浓度范围内的甘蔗废糖蜜能明显增加绿豆插条下胚轴不定根的数目、根长、根干重及生根范围,并促进不定根内可溶性糖含量和不定根系活力提高。     

Effects of orchinol and related phenanthrenes on the enzymic degradation of indole-3-acetic acid

Orchinol, hircinol, loroglossol and certain related phenanthrenes inhibited horseradish peroxidase-catalysed IAA degradation to a varied degree. Among     

微域环境因子对落基山圆柏插穗生根的影响

以8年生落基山圆柏(Juniperus scopulorum)的嫩枝为试验材料, 采用不同扦插密度和基质等处理措施, 研究了微域环境因子对插穗生根的影响。结果表明, 两种不同扦插密度的生根部位、愈伤率、生根率、炼存率、生根效果指数(root effect index, REI)、离散度指数(rooting dispersion index, RDI)和分形特征均存在显著差异。综合分析生根率、炼存率、REI和RDI等发现, 密插处理的效果好于稀插, 稀插处理的插穗生根能力较差, 生根性状离散度较大。密插处理的插穗的根系平均分形维数是稀插处理的1.24倍, 两者差异极显著(p < 0.01)。不同扦插密度下插穗的生根部位和生根机制不同: 插穗在密插处理下形成诱生根, 在稀插处理下形成原基根。不同的扦插密度造成了落基山圆柏微域环境的显著差异, 但同一密度下不同基质种类对微域环境因子的调控作用有限。密插处理下插穗的微域环境相对湿度较高(最高可达83.5%), 温度较低, 光合有效辐射较小。这些环境因子的差异导致密插处理下插穗的净光合速率(P_n)较高, 蒸腾速率(T_r)较低。在0-60天内, 密插和稀插处理的插穗的P_n均呈上升趋势, 并且二者相差的幅度随着试验时间的延长而迅速增大; 在60天以后, 二者均呈下降趋势, 相差幅度基本保持不变。密插处理下的T_r值在0-30天内基本保持不变, 而此时稀插处理下的T_r迅速增加。在30-60天内密插处理下的T_r快速增加, 60天时达到最大值, 但仍低于稀插处理。这些结果表明, 外部微域环境因子对插穗生根的影响是通过影响其内在生理指标来实现的, 插穗营养状况的差异是造成生根机制不同的主要原因。     

Synergistic effect of gibberellic acid and indole-3-acetic acid on rooting in stem cuttings of Abelmoschus esculentus Moench

Indole-3-acetic acid (IAA) and gibberellic acid (GA₃) enhanced the formation of roots on the stem cuttings of Abelmoschus esculentus. The effect increased considerably when both IAA and GA₃ were applied together.     

Endogeneous levels of indole-3-acetic acid and abscisic acid during the rooting of Cotinus coggygria cuttings taken at different times of the year

Cuttings of Cotinus coggyria cv Royal Purple rooted well in the spring but not at all later in the season. Levels of free and conjugated IAA and ABA were measured in cuttings taken at different times of the year. Hormones were measured in the leaf, the upper stem and the lower stem (rooting zone). In cuttings taken in early June the level of IAA was much higher than that of conjugated IAA. In late July the opposite was found. No significant differences in ABA levels were found although the ABA/IAA ratio changed dramatically.     

A relationship between irradiation, carbohydrates and rooting in cuttings of Pisum sativum

Rooting ability was studied for cuttings derived from pea plants ( Pisum sativum , L. cv. Alaska) grown in controlled environment rooms. When the cuttings were rooted at 70 μmol m⁻² s⁻, ¹ (photosynthetic photon flux density) or more, a stock plant irradiance at 100 μmol m⁻² s⁻¹ decreased rooting ability in cuttings compared to 5 μmol m⁻², s⁻¹, However, cuttings rooted at 160 μmol m⁻² s⁻¹ formed more roots compared to 5 (μmol m⁻² s⁻¹. Although a high irradiance increased the number of roots formed, it could not overcome a decreased potential for root formation in stock plants grown at high irradiance. Light compensation point and dark respiration of cuttings decreased by 70% during the rooting period, and the final levels were strongly influenced by the irradiance to the cuttings. Respiratory O₂ uptake decreased in the apex and the base of the cutting from day 2 onwards, whereas a constant level was found in the leaves. Only the content of extractable fructose, glucose, sucrose and starch varied during the early part of the rooting period. We conclude that the observed changes in the cuttings are initiated by excision of the root system, and are not involved in the initiation of adventitious roots.     

Urea derivatives on the move: cytokinin-like activity and adventitious rooting enhancement depend on chemical structure

Urea derivatives are synthetic compounds, some of which have proved to be positive regulators of cell division and differentiation. N -phenyl- N '-(2-chloro-4-pyridyl)urea (forchlorofenuron, CPPU) and N -phenyl- N '-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ), well known urea cytokinin representatives, are extensively used in in vitro plant morphogenesis studies, as they show cytokinin-like activity often exceeding that of adenine compounds. In recent years, renewed interest in structure–activity relationship studies allowed identification of new urea cytokinins and other urea derivatives that specifically enhance adventitious root formation. In this review, we report the research history of urea derivatives, new insights into their biological activity, and recent progress on their mode of action.     

Effects of auxin and irradiance on the rooting of cuttings of Pinus sylvestris

Abstract Seedlings of Pinus sylvestris L. were grown under controlled conditions (temperature 20°C, photoperiod 17 h) at two irradiances, 8 or 40 W m^-2. Hypocotyl cuttings were excised and rooted at different irradiances in tap water solutions of indolebutyric acid (IBA). The fastest rooting and highest rooting percentage were obtained with cuttings from stock plants grown at 8 W m^-2 and treated with 10^-5M IBA for 21 days. The concentration of 10^-4M IBA inhibited root formation. In comparable treatments rooting was always better in cuttings from stock plants grown at 8 W m^-2 than in cuttings from stock plants grown at 40 W m^-2. The irradiance during the rooting period had only a minor influence on rooting. When cuttings from plants irradiated with 40 W m^-2 were treated with 10^-5M IBA for 21 days the rooting percentage almost reached the same level as in untreated cuttings from stock plants given 8 W m^-2. In cuttings treated with IBA during the whole rooting period, rooting was depressed in comparison to untreated cuttings. Aeration of the 10^-4M IBA solution increased the rooting percentage, but aeration had no effect on untreated cuttings and on cuttings treated with lower IBA concentrations.     

New phenolic inhibitors of the peroxidse-catalysed oxidation of indole-3-acetic acid

Previously we reported two metabolites of the insecticide carbofuran as persistent inhibitors of the peroxidase-catalysed oxidtion ofindole-3-acetic acid. In searching for more active inhibitors of this type, we have found that 5-hydroxy-2,2-dimethylchromene (β-tubanol), 2′,6′-dihydroxycetophenone oxime, 5-hydroxy-2,2-dimethylchroman, 2′,6′-dihydroxyacetophenone and 2,6-dihydroxybenzoic acid methyl ester were more active than the carbofuran metabolite 7-hydroxy-2,2-dimethyl-3-oxo-2,3-dihydrobenzofuran. Resorcinol, 5-hydroxy-2,2-dimethylchroman-4-one, 3-hydroxy-5-methoxy-2,2-dimethylchroman-4-one and 5-hydroxy-2-methylchrom-4-one were also inhibitory but with less activity. The new inhibitors differed from the well-known phenolic inhibitors such as caffeic acid in inhibition kinetics as demonstrated by the rate of disappearance of indole-3-acetic acid, the rate of formation of the oxidation products, and the transient spectral change in the enzyme.