Stimulation of adventitious root formation in non-woody stem cuttings by uridine

Uridine strongly stimulated adventitious root formation in stem cuttings of sunflower (Helianthus annuus L.), mung bean (Vigna radiata L.) and common bean (Phaseolus vulgaris L.). A dose response curve of uridine induced rooting showed that the optimum concentration of uridine was 0.1 µM. At all concentrations employed, uridine had no significant effect on root elongation. The rooting response of stem cuttings to the optimal concentration of indole-3-butyric acid (10 µM) in combination with 0.1 µM uridine did not significantly differ from their response to either of these compounds when applied alone. However, the rooting response of the cuttings to sub-optimal IBA (0.01 µM) was significantly stimulated by uridine. These findings suggested that uridine may have stimulated rooting by increasing the sensitivity of the rooting tissue to auxin.     

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.     

Abscisic-acid-stimulated rooting of stem cuttings

Summary Abscisic acid (ABA) has been found to stimulate rooting of stem cuttings of mung beans and English ivy. ABA partially overcame the inhibitory effect of gibberellic acid on root formation of mung bean cuttings but at the concentrations used did not overcome the inhibitory effect of kinetin on root formation.     

Caffeic acid affects early growth, and morphogenetic response of hypocotyl cuttings of mung bean (Phaseolus aureus)

Caffeic acid (CA) is one of the most common cinnamic acids ubiquitously present in plants and implicated in a variety of interactions including allelopathy among plants and microbes. This study investigated the possible interference of CA with root growth and the process of rhizogenesis in hypocotyl cuttings of mung bean (Phaseolus aureus=Vigna radiata). Results indicated that CA (0-1000 microM) significantly suppressed root growth of mung bean, and impaired adventitious root formation and root length in the mung bean hypocotyl cuttings. Further investigations into the role of CA in hampering root formation indicated its interference with the biochemical processes involved in rooting process at the three stages - root initiation (third day; RI), root expression (fifth day; RE), and post-expression (seventh day; PE) - of rhizogenesis. CA caused significant changes in the activities of proteases, peroxidases (PODs), and polyphenol oxidases (PPOs) during root development and decreased the content of total endogenous phenolics (TP) in the hypocotyl cuttings. The enhanced activity of PODs and PPOs, though, relates to lignification and/or phenolic metabolism during rhizogenesis; yet their protective role to CA-induced stress, especially during the PE phase, is not ruled out. At 1000 microM CA, where rooting was significantly affected, TP content was very high during the RI phase, thus indicating its non-utilization. The study concludes that CA interferes with the rooting potential of mung bean hypocotyl cuttings by altering the activities of PODs and PPOs and the endogenous TP content that play a key role in rhizogenesis.     

Enhancement of adventitious root formation in mung bean cuttings by 3,5-dihalo-4-hydroxybenzoic acids and 2,4-dinitrophenol

3,5-Dihalo-4-hydroxybenzoic acids enhanced adventitious root formation in mung bean (Vigna radiata L.) cuttings. 3,5-Diiodo-4-hydroxybenzoic acid was more active than 3,5-dichloro-4-hydroxybenzoic acid, increasing the number of roots formed by about 4-fold. 2,4-Dinitrophenol also enhanced significantly adventitious root formation in mung bean cuttings. The phenolic compounds were active with or without indole-3-acetic acid. The possible mechanism by which these phenolic compounds enhance rooting is discussed.Abbreviations CCCP carbonyl cyanide 3-chlorophenylhydrazone - DIHB 3,5-diiodo-4-hydroxybenzoic acid - DNP 2,4-dinitrophenol     

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.     

脱落酸对绿豆下胚轴不定根发生的影响

以10^-4 mol/L脱落酸(ABA)处理绿豆种子24 h,在幼苗下胚轴长6 cm时,切除根部作为插条,研究ABA对插条不定根发生及插条基部细胞周期时相的影响。结果表明,ABA可促进下胚轴插条不定根发生,增加生根数和生根范围;ABA提高插条基部细胞色氨酸转氨酶、吲哚丙酮酸脱羧酶和吲哚乙醛脱氢酶的比活性,增加吲哚乙酸含量,同时进入细胞周期S期的基部细胞数目增加,促进DNA合成,有利于不定根的发生。     

Promotion of adventitious root formation by 4-chlororesorcinol: A polyphenol oxidase inhibitor

The extent of rooting in cuttings of Phaseolus vulgaris L., and Vigna radiata Wilcz. was affected by 4-chlororesorcinol, a polyphenol oxidase inhibitor. More root primordia and more roots were formed after 4-chlororesorcinol treatment both with and without 10^-5M Indole butyric acid. Promotion of rooting was observed also in cuttings of Elaeagnus pungens, Gypsophilia elegans and Kalanchoe blossfeldiana. The enhancement in bean and mung bean was accompanied by a concomitant wider spatial distribution of the primordia and the resulting adventitious roots. The formation of primordia in the treated cuttings was delayed by 12–24 hours, compared to untreated cuttings. The treatment was effective only when given during the first hours after the preparation of the cutting of bean and mung bean, suggesting involvement in the initiation stage. Hypocotyl extracts of mung bean cuttings, pretreated with 4-chlororesorcinol, exhibited reduced polyphenol oxidase activity. The inhibition was not reversed by washing of the treated extract in 50% acetone or by an overnight dialysis, suggesting tight or maybe even irreversible binding of the inhibitor to the enzyme.Abbreviations 4-CR 4-chlororesorcinol - IBA Indole butyric acid - PPO polyphenol oxidase     

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.The biological properties of the avocado rooting promoter may be comparable to those of -(p-chlorophenoxy) isobutyric acid (PCIB) which acts as an anti-auxin in certain bioassays and, nevertheless, promotes the rooting of mung bean cuttings.     

Marigold,Castor Bean,and Chrysanthemum as Controls of Meloidogyne incognita and Pratylenchus alleni

Root and soil populations of Meloidogyne incognita were significantly fewer from marigold, castor bean, and chrysanthemum than from tomato roots and soil, but not from fallow soil. Root populations of Pratvlenchus alleni were significantly fewer from marigold, castor bean, and chrysanthemum than from tomato: marigold had the fewest. Root populations of M. incognita and P. alleni from tomato simultaneously cultivated with marigold, castor bean, and chrysanthemum were significantly fewer than from tomato cultivated alone. Aborted giant cells and dead M. incognita (larvae and females) were observed in roots of marigold and castor bean, but not in chrysanthemum or tomato. Significantly more males than females occurred in castor bean roots. lnfcction sites of P. alleni appeared normal in all hosts. Thin-layer and column chromatography of alcoholic extracts from castor bean revealed no nematicidal thiophenc derivatives.     

l-DOPA (l-3,4-dihydroxyphenylalanine) affects rooting potential and associated biochemical changes in hypocotyl of mung bean, and inhibits mitotic activity in onion root tips

A study was undertaken to explore the effect of l-DOPA (l-3,4-dihydroxyphenylalanine) on the rooting potential of hypocotyl cuttings of mung bean (Phaseolus aureus Roxb. var. SML-32) and related biochemical changes at the post-expression phase. At lower concentrations of (0.0001–0.1 mM) l-DOPA, there was no change in rooting potential, though the average number of roots per cutting and root length were significantly decreased (except at 0.0001 mM). However, at 1.0 mM concentration, a 50% inhibition in rooting potential was noticed and the root number and length were severely reduced. In contrast, at 2.5 mM l-DOPA, none of the hypocotyl cutting rooted. The decrease in rooting potential was associated with a significant effect on the biochemical changes measured in terms of protein and carbohydrate metabolism and activity of peroxidases. In the l-DOPA treated hypocotyl cuttings, there was a significant reduction in the protein and carbohydrate content, whereas activities of associated enzymes proteases and amylases decreased, particularly at higher treatment concentration (>1.0 mM). It indicated negative effect of l-DOPA on these two important metabolic processes. Likewise, activity of peroxidases also decreased in the l-DOPA treated hypocotyl mung bean cuttings thereby indicating its role in suppressing rhizogenesis as the enzyme is involved in lignification process during cell division. l-DOPA suppressed mitotic activity in the root tip cells of onion indicating thereby its interference with the cell division, which is required for the formation of new meristematic tissue during rhizogenesis. Based on the obtained results, it is concluded that l-DOPA interferes with the various biochemical processes in the mung bean hypocotyl cuttings thereby affecting their rooting potential.     

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.     

Isolation, Purification, and Characterization of an Endogenous Root-promoting Factor Obtained from Basal Sections of Pear Hardwood Cuttings

Basal segments taken from Old Home and Bartlett pear hardwood cuttings collected at intervals during the rooting period in September were extracted with ethanol and fractionated by paper chromatography in different solvent systems. Different zones on the chromatograms were bioassayed by the mung bean rooting test, which showed high levels of promotion in Old Home basal extracts when the cuttings were obtained during the period of maximum rooting. Extracts from Bartlett cuttings, however, showed considerably less promotion activity in the bioassay but did show high levels of inhibitory activity.

After the easily-rooted Old Home cuttings had been in the rooting medium for 10 days, a highly active endogenous root-promoting material was found in extracts from basal segments of cuttings having buds and which had been treated with indolebutyric acid. Similar extracts obtained from disbudded cuttings, or from cuttings with buds but not treated with indolebutyric acid, lacked this rooting-factor. Extracts obtained from all types of the difficult-to-root Bartlett cuttings also lacked this rooting-factor. The latter is believed to be produced by physiologically active Old Home buds, and is very effective in the mung bean bioassay, even at extremely low concentrations.

From paper chromatographic studies, tests with spray reagents, solubility determinations, biological tests, UV spectrum analysis, and infrared spectroscopy, it is believed that this rooting factor could be a condensation product between exogenous auxin (indolebutyric acid) and a phenolic compound produced by physiologically active Old Home pear buds.

     

Root-promoting Substances in Salix alba

Root-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.     

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.     

Effect of abscisic acid on endogenous IAA, auxin protector levels and peroxidase activity during adventitious root initiation in Vigna radiata cuttings

Endogenous levels of free and conjugated IAA, auxin protectors (Prs) and peroxidase (PER) activity and their relation to adventitious root initiation (ARI) were investigated at the potential sites of adventitious rooting in relation to exogenous application of 250 μM ABA during the first 120 h after treatment. Cuttings from 7-day-old mung bean [Vigna radiata (L.) Wilcz.] seedlings were treated with 125, 250, and 500 μM ABA for 24 h. ABA significantly stimulated ARI but extremely inhibited epicotyl growth as compared to control. Free and conjugated IAA were measured by reversed-phase high performance liquid chromatography while Prs and PER activities were measured spectrophotometrically. The present results also indicate that endogenous free IAA levels peaked later in ABA-treated cuttings than that in control, suggesting that ABA extended the length of the induction phase of rooting process in treated cuttings and that might explain the significant delay of the appearance of roots at the treated cuttings. Higher level of IAA conjugates was found in ABA-treated cuttings than that in untreated ones. Pr level also peaked later in ABA-treated cuttings than that in control, indicating that ABA extended the period of Pr activity. An initial temporary decrease of PER activity was found in associating with high levels of free IAA and Prs during most of the primary events, while the opposite occurred during the secondary events of adventitious rooting process in both treated and untreated cuttings. Thus, ABA may stimulate ARI in mung bean Vigna radiata cuttings by regulating the concentration and /or activities of endogenous IAA, Prs, and PER activity in favor of inducing a large number of adventitious roots at their potential sites of adventitious rooting.     

Hydrogen peroxide acts as a signal molecule in the adventitious root formation of mung bean seedlings

Hydrogen peroxide (H₂O₂), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In this study we demonstrated that the exogenous H₂O₂ was able to promote the formation and development of adventitious roots in mung bean seedlings. Treatments with 1–100 mM H₂O₂ for 8–18 h significantly induced the formation and development of adventitious roots. Catalase (CAT) and ascorbic acid, which are H₂O₂ scavengers or inhibitors, eliminated the adventitious root-promoting effects of exogenous H₂O₂. H₂O₂ may have a downstream signaling function in the auxin signaling pathway and be involved in auxin-induced adventitious root formation. 2,3,5-Triiodobenzoic acid (TIBA), an inhibitor of auxin polar transport, strongly inhibited adventitious rooting of mung bean seedlings; however, the inhibiting effects of TIBA on adventitious rooting can be partially reversed by the exogenous IBA or H₂O₂. Diphenylene iodonium (DPI) strongly inhibits the activity of NADPH oxidase, which is one of the main sources of H₂O₂ formation in plant cells. DPI treatment strongly inhibited the formation of adventitious roots in mung bean, but the inhibitory effects of DPI on rooting can be partially reversed by the exogenous H₂O₂ or IBA. This indicates that the formation of adventitious roots was blocked once the generation of H₂O₂ through NADPH oxidase was inhibited, and H₂O₂ mediated the IBA-induced adventitious root formation. Furthermore, a rapid increase in the endogenous level of H₂O₂ was detected during incubation with water 12–36 h after the primary root removal in mung bean seedlings. Three hours after the primary root removal, the generation of endogenous H₂O₂ was markedly induced in IBA-treated seedlings in comparison with water-treated seedlings. This implies that IBA induced overproduction of H₂O₂ in mung bean seedlings, and that IBA promoted adventitious root formation via a pathway involving H₂O₂. Results obtained suggest that H₂O₂ may function as a signaling molecule involved in the formation and development of adventitious roots in mung bean seedlings.     

Endogenous Levels of Growth Regulators and Their Relationship to the Rooting of Dahlia Cuttings

The relationship between the level of endogenous growth regulators and the rooting ability of dahlia cuttings was investigated. Easy-to-root vegetative cuttings were compared with difficult-to-root, flower bud bearing cuttings and the easy-to-root cv. Choot Hashani was compared with the difficnlt-to-root cv. Orpheo. No differences in the level of extracted or diffusable auxin, nor in the level of rooting cofactors, were found between easy-to-root and difficult-to-root cuttings. No activity could be found at the R_f zone corresponding to Cofactor 4 which is considered the main rooting cofactor in other plants. Higher inhibitor activity levels (assayed by the wheat coleoptile test and the mung bean rooting test) were found in difficult-to-root than in easily rooted cuttings. Furthermore, the inhibitor activity level in exadates from decapitated plants, was higher in esodates from plants which bore difficult-to-root cuttings than from plants bearing easy-to-root ones. Grafting of an easy-to-root plant onto a difficult-to-root stock caused inhibition of rooting in the cuttings taken from the scion. Results suggest that inhibitors formed in the root system, move upwards and accumulate in the plant, there causing the inhibition of rooting. Evidence from chromatographic comparisons and exogenous treatments with ABA indicate that the main inhibitor involved in the inhibition of rooting in dahlia cuttings is not ABA.     

绿豆插条生根过程中内源激素含量变化

绿豆插条离体后其IAA含量出现一个峰值,乙烯利处理的IAA峰值出现在第6小时,未经乙烯利处理的出现在第12小时,与插条生根峰出现时间相符.乙烯利处理与否的插条生根过程中,内源GA3含量在0～30h内呈下降趋势,随后略微上升;内源ABA含量先升后降;细胞分裂素ZT和ZR含量在总体上是下降的.     

Isolation of Chrysartemins A and B as Rooting Cofactors in Chrysanthemum morifolium

From leaves of Chrysanthemum morifolium two stimulants for root initiation in mung bean cuttings have been isolated and identified as chrysartemins A and B (I and II). These substances showed synergistic activity on rooting with indoleacetic acid and were proved to be constituents of the “cofactor 4” designated by Hess.