生长素和模拟微重力效应对大白菜不定根形态发生的影响

在生长素诱导下,大白菜(Brassicacampestris．Spp．Pekinensis)的下胚轴切段显示了一定的发根能力,其中,0．4—1．0mg／LIAA显著地促进大白菜不定根的发生。在生长素诱导24h后,可借助显微切片观察到下胚轴切面明显的解剖学变化首先是中柱鞘内靠近韧皮部的薄壁细胞的细胞质与细胞核变浓,染色加深,部分细胞分裂;随后是分裂的细胞团增大,逐渐形成根原基并分化出根冠。当下胚轴切段培养5天后,大量不定根穿破皮层,达到肉眼可见的程度。同一外植体中不定根的发育是不同步的,下胚轴不同部位的切段具有不同的发根能力;当下胚轴切段在培养基上反插时,提高外源IAA可修饰根发生的极性,提高蔗糖浓度能增强IAA的修饰作用;在模拟微重力效应条件下,不定根发生的极性没有明显变化,但是,增加了外植体对IAA诱导发根的敏感性。本结果为进一步研究不定根发生的分子机制建立了试验系统。     

Sugar-induced adventitious roots in<Emphasis Type="Italic"> Arabidopsis</Emphasis> seedlings

The effects of sugars on root growth and on development of adventitious roots were analyzed in Arabidopsis thaliana. Seeds were sown on agar plates containing 0.0–5.0% sugars and placed vertically in darkness (DD) or under long day (LD, 16 h:8 h) conditions, so that the seedlings were constantly attached to the agar medium. In the sucrose-supplemented medium, seedlings showed sustained growth in both DD and LD. However, only dark-grown seedlings developed adventitious roots from the elongated hypocotyl. The adventitious roots began to develop 5 days after imbibition and increased in number until day 11. They could, however, be initiated at any position along the hypocotyl, near the cotyledon or the primary root. They were initiated in the pericycle in the same manner as ordinary lateral roots. Sucrose, glucose and fructose greatly stimulated the induction of adventitious roots, but mannose or sorbitol did not. Sucrose at concentrations of 0.5–2.0% was most effective in inducing adventitious roots, although 5.0% sucrose suppressed induction. Direct contact of the hypocotyl with the sugar-supplemented agar medium was indispensable for the induction of adventitious roots. Electronic Publication     

Chloramphenicol effects on adventitious root production by radish hypocotyls

Abstract

The excision of the root accelerates greatly the formation of adventitious roots in the hypocotyl of etiolated radish seedlings, but if the seedlings develop in CAP 1×10^?4M, no adventitious root are induced after cutting. IAA either alone or associated with CAP, significantly increases the number of primordia in normal hypocotyls if given at the moment of cutting, while it has not stimulatory effect on the hypocotyls of seedlings grown in CAP. IAA has significant effect on both elongation and tickening of hypocotyl segments prepared from seedlings grown in CAP, and this could indicate a specific action of the inhibitor either on a particular process or on particular cells.

The endodermis and the pericycle, which are the two cell layers implicated in the formation of the adventitious roots, could be the mediators of this particular effect of CAP in rooting.     

N,N′-bis-(2,3-Methylenedioxyphenyl)urea and N,N′-bis-(3,4-methylenedioxyphenyl)urea enhance adventitious rooting in Pinus radiata and affect expression of genes induced during adventitious rooting in the presence of exogenous auxin

We have analyzed the effect of N,N′-bis-(2,3-methylenedioxyphenyl)urea (2,3-MDPU) and N,N′-bis-(3,4-methylenedioxyphenyl)urea (3,4-MDPU), two symmetrically substituted diphenylurea derivatives with no auxin or cytokinin-like activity, on the rooting capacity of Pinus radiata stem cuttings. Results indicate that both diphenylurea derivatives enhance adventitious rooting in the presence of exogenous auxin (indole-3-butyric acid, IBA), even at low auxin concentration, in rooting-competent cuttings, but have no effect on the adventitious rooting of low or null competent-to-root cuttings. Histological analyses show that, in the simultaneous presence of MDPUs and low concentration of exogenous auxin, adventitious root formation is induced in the cell types that retain intrinsic competence to form adventitious roots in response to auxin. The time course of cellular events leading to root formation and the time of root emergence are closely similar to that observed in cuttings treated only with higher auxin concentration. In addition, the mRNA level of a P. radiata SCARECROW-LIKE gene, which is significantly induced in the presence of the optimal concentration (10 μM) of exogenous auxin needed for cuttings to root, is increased in the presence of MDPUs and low concentration of exogenous auxin (1 μM). The expression of a P. radiata SHORT-ROOT gene in rooting-competent cuttings during adventitious rooting is also affected by the presence of MDPUs when combined with auxin. As MDPUs do not affect the expression of either gene in the absence of exogenous auxin, but only in its presence, we suggest that MDPUs could interact, directly or indirectly, with the auxin-signalling pathways in rooting-competent cuttings during adventitious rooting.     

Gibberellins inhibit adventitious rooting in hybrid aspen and Arabidopsis by affecting auxin transport

Knowledge of processes involved in adventitious rooting is important to improve both fundamental understanding of plant physiology and the propagation of numerous plants. Hybrid aspen (Populus tremula × tremuloïdes) plants overexpressing a key gibberellin (GA) biosynthesis gene (AtGA20ox1) grow rapidly but have poor rooting efficiency, which restricts their clonal propagation. Therefore, we investigated the molecular basis of adventitious rooting in Populus and the model plant Arabidopsis. The production of adventitious roots (ARs) in tree cuttings is initiated from the basal stem region, and involves the interplay of several endogenous and exogenous factors. The roles of several hormones in this process have been characterized, but the effects of GAs have not been fully investigated. Here, we show that a GA treatment negatively affects the numbers of ARs produced by wild‐type hybrid aspen cuttings. Furthermore, both hybrid aspen plants and intact Arabidopsis seedlings overexpressing AtGA20ox1, PttGID1.1 or PttGID1.3 genes (with a 35S promoter) produce few ARs, although ARs develop from the basal stem region of hybrid aspen and the hypocotyl of Arabidopsis. In Arabidopsis, auxin and strigolactones are known to affect AR formation. Our data show that the inhibitory effect of GA treatment on adventitious rooting is not mediated by perturbation of the auxin signalling pathway, or of the strigolactone biosynthetic and signalling pathways. Instead, GAs appear to act by perturbing polar auxin transport, in particular auxin efflux in hybrid aspen, and both efflux and influx in Arabidopsis.     

生长素、乙烯和一氧化氮对拟南芥下胚轴插条形成不定根的调节

研究生长素、乙烯和一氧化氮（NO）对拟南芥下胚轴插条形成不定根的调节,以及生长素和乙烯信号转导成员在IAA促进不定根形成中的作用的结果表明：拟南芥切条以IAA和硝普钠（N0供体）单独处理7d后的不定根形成均受到促进,其中以50μmol·L^-1 IAAμmol·L^-1 SNP的促进作用为最强,乙烯的促进作用不明显;生长素运输和信号转导以及乙烯信号转导相关突变体对IAA促进生根作用的敏感性比野生型有所下降,特别是IAA14功能获得型的突变体。IAA和NO在促进不定根形成中有协同效应。     

Distinct modes of adventitious rooting in Arabidopsis thaliana

The literature describes different rooting protocols for Arabidopsis thaliana as models to study adventitious rooting, and results are generally perceived as comparable. However, there is a lack of investigations focusing on the distinct features, advantages and limitations of each method in the study of adventitious rooting with both wild-type (WT) ecotypes and their respective mutants. This investigation was undertaken to evaluate the adventitious rooting process in three different experimental systems, all using A. thaliana, analysing the same rooting parameters after transient exposure to auxin (indole-3-acetic acid) and control conditions: excised leaves, de-rooted plants and etiolated seedlings. The founding tissues and sites of origin of roots differed depending on the system used, whereas all rooting patterns were of the direct type (i.e., without callus formation). None of the systems had an absolute requirement for exogenous auxin, although rooting was enhanced by this phytohormone, with the exception of de-rooted plants, which had adventitious rooting strongly inhibited by exogenous auxin. Root elongation was much favoured in isolated leaves. Auxin-overproducing mutants could not be used in the detached leaf system due to precocious senescence; in the de-rooted plant system, these mutants had a WT-like rooting response, whereas the expression of the 'rooty' phenotype was only evident in the etiolated seedling system. Adventitious rooting of etiolated WT seedlings in the presence of exogenous auxin was inhibited by exogenous flavonoids, which act as auxin transport inhibitors; surprisingly, the flavonoid-deficient mutant chs had a lower rooting response compared to WT. Although Arabidopsis is an excellent model system to study adventitious rooting, physiological and developmental responses differed significantly, underlining the importance of avoiding data generalisation on rooting responses derived from different experimental systems with this species.     

The Relationship Between Lateral-Root Distribution and Endodermis and Pericycle Cell Length in Allium cepa L. Adventitious Roots

Endodermis and pericycle cell lengths were measured in intactand decapitated adventitious roots of Allium cepa L. Decapitationhad no effect on cell length in mature portions of the root,although it affected more immature cells, impeding normal elongation.Cell length shows a characteristic pattern in different zonesof the adventitious root: cells in the medial region were moremarkedly elongated. The number of lateral root primordia wasalso determined in different zones of the adventitious root.The possible relationship between lateral root distributionpattern and cell length in the endodermis and pericycle is discussed. Allium cepa, onion, endodermis, pericycle, lateral root, cell length     

Mediators,Genes and Signaling in Adventitious Rooting

Adventitious roots are a post-embryonic root which arise from the stem and leaves and from non-pericycle tissues in old roots and it is one of the most important ways of vegetative propagation in plants. Many exogenous and endogenous factors regulate the formation of adventitious roots, such as Ca²⁺, sugars, auxin, polyamines, ethylene, nitric oxide, hydrogen peroxide, carbon monoxide, cGMP, MAPKs and peroxidase, etc. These mediators are thought to function as signaling and mediate auxin signal transduction during the formation of adventitious roots. To date, only a few genes have been identified that are associated with the general process of adventitious rooting, such as ARL1, VvPRP1, VvPRP2, HRGPnt3, LRP1 and RML, etc. Auxin has been shown to be intimately involved in the process of adventitious rooting and function as crucial role in adventitious rooting. Great progress has been made in elucidating the auxin-induced genes and auxin signaling pathway, especially in auxin response Aux/IAA and ARF genes family and the auxin receptor TIR1. Although, some of important aspects of adventitious rooting signaling have been revealed, the intricate signaling network remains poorly understood.     

Effect of auxins and plant oligosaccharides on root formation and elongation growth of mung bean hypocotyls

The interaction of auxins – IAA, IBA or NAA – with galactoglucomannan oligosaccharides (GGMOs) on adventitious root formation and elongation growth of mung bean hypocotyl cuttings was studied. GGMOs induced adventitious roots in the absence of auxins; however, their effect was lower compared with IBA or NAA. On the other hand, in the presence of auxins, GGMOs inhibited adventitious root induction. Their effect depended on the concentration of oligosaccharides and the type of auxin used. The highest inhibition effect of GGMOs at a concentration of 10⁻⁸ M in the presence of IBA and NAA was observed. In the presence of IAA their inhibition was non-significant in regard to the concentration. The interaction of auxins with GGMOs resulted in the formation of adventitious roots on a shorter part of hypocotyls compared with the effect of auxins alone. However, roots were induced more extensively along the hypocotyls treated with GGMOs compared with the control. GGMOs inhibited the length of induced adventitious roots in the presence of IAA, while in combination with IBA or NAA they were ineffective. The elongation of hypocotyls induced by IAA or IBA was inhibited by GGMOs, too. However, in the presence of NAA or by endogenous growth they were without any significant effect on elongation growth. These findings suggest that GGMOs in certain concentrations might inhibit rooting and the elongation process dependant on auxin used.     

Role of auxin and its modulators in the adventitious rooting of <Emphasis Type="Italic">Eucalyptus</Emphasis> species differing in recalcitrance

It is well established that auxins play a central role in the determination of rooting capacity, which is essential for vegetative propagation. Recent studies with apple trees have pointed to significant effects of auxin stability, wound related phenolics and ethylene production in the control of adventitious rooting. In the present study, a comparative analysis of the adventitious rooting of microcuttings of Eucalyptus saligna (easy-to-root species) and Eucalyptus globulus (difficult-to-root species) was carried out with different types of auxins, light intensities, presence or absence of apical meristem, different concentrations of phenolic compounds and presence or absence of an ethylene action inhibitor. Parameters evaluated were the percent rooting, number of roots per rooted cutting, length of longest root and mean rooting time. Results showed that auxins of intermediate stability are more favorable to rooting (particularly for the recalcitrant species), higher light intensities in the presence of exogenous auxins promote the rooting response, the absence of meristematic apex or externally supplied phenolics are not limiting for the rooting induced by exogenous auxins, and ethylene appears to play a minor role in the development of adventitious roots in microcuttings of Eucalyptus, indicating that the rhizogenic response results from direct effect of auxins.     

Cell-type action specificity of auxin on Arabidopsis root growth

The plant hormone auxin plays a critical role in root growth and development; however, the contributions or specific roles of cell-type auxin signals in root growth and development are not well understood. Here, we mapped tissue and cell types that are important for auxin-mediated root growth and development by manipulating the local response and synthesis of auxin. Repressing auxin signaling in the epidermis, cortex, endodermis, pericycle or stele strongly inhibited root growth, with the largest effect observed in the endodermis. Enhancing auxin signaling in the epidermis, cortex, endodermis, pericycle or stele also caused reduced root growth, albeit to a lesser extent. Moreover, we established that root growth was inhibited by enhancement of auxin synthesis in specific cell types of the epidermis, cortex and endodermis, whereas increased auxin synthesis in the pericycle and stele had only minor effects on root growth. Our study thus establishes an association between cellular identity and cell type-specific auxin signaling that guides root growth and development.     

Auxin and light control of adventitious rooting in Arabidopsis require ARGONAUTE1

Adventitious rooting is a quantitative genetic trait regulated by both environmental and endogenous factors. To better understand the physiological and molecular basis of adventitious rooting, we took advantage of two classes of Arabidopsis thaliana mutants altered in adventitious root formation: the superroot mutants, which spontaneously make adventitious roots, and the argonaute1 (ago1) mutants, which unlike superroot are barely able to form adventitious roots. The defect in adventitious rooting observed in ago1 correlated with light hypersensitivity and the deregulation of auxin homeostasis specifically in the apical part of the seedlings. In particular, a clear reduction in endogenous levels of free indoleacetic acid (IAA) and IAA conjugates was shown. This was correlated with a downregulation of the expression of several auxin-inducible GH3 genes in the hypocotyl of the ago1-3 mutant. We also found that the Auxin Response Factor17 (ARF17) gene, a potential repressor of auxin-inducible genes, was overexpressed in ago1-3 hypocotyls. The characterization of an ARF17-overexpressing line showed that it produced fewer adventitious roots than the wild type and retained a lower expression of GH3 genes. Thus, we suggest that ARF17 negatively regulates adventitious root formation in ago1 mutants by repressing GH3 genes and therefore perturbing auxin homeostasis in a light-dependent manner. These results suggest that ARF17 could be a major regulator of adventitious rooting in Arabidopsis.     

Adventitious rooting in hypocotyls of sunflower (Helianthus annuus) seedlings. IV. The role of changes in endogenous free and conjugated indole‐3‐acetic acid

We have studied the role of endogenous auxin on adventitious rooting in hypocotyls of derooted sunflower (Helianthus annuus L. var. Dahlgren 131) seedlings. Endogenous free and conjugated indole-3-acetic acid (IAA) were measured in three segments of hypocotyls of equal length (apical, middle, basal) by using gas chromatography-mass spectrometry with [¹³C₆]-IAA as an internal standard. At the time original roots were excised (0 h), the free IAA level in the hypocotyls showed an acropetally decreasing gradient, but conjugated IAA level increased acropetally; i.e. free to total IAA ratio was highest in the basal portion of hypocotyls. The basal portion is the region where most of root primordia were found. Some primordia were seen in this region within 24 h after the roots were excised. The quantity of free IAA in the middle portion of the hypocotyl increased up to 15 h after excision and then decreased. In this middle region there were fewer root primordia, and they could not be seen until 72 h. In the apical portion the amount of free IAA steadily increased and no root primordia were seen by 72 h. Surgical removal of various parts of the hypocotyl tissues caused adventitious root formation in the hypocotyl regions where basipetally transported IAA could accumulate. Reduction in the basipetal flow of auxin by N-1-naphthylphthalamic acid and 2,3,5-tri-iodobenzoic acid resulted in fewer adventitious roots. The fewest root primordia were seen if the major sources of endogenous auxin were removed by decapitation of the cotyledons and apical bud. Exogenous auxins promoted rooting and were able to completely overcome the inhibitory effect of 2,3,5-tri-iodobenzoic acid. Exogenous auxins were only partially able to overcome the inhibitory effect of decapitation. We conclude that in sunflower hypocotyls endogenously produced auxin is necessary for adventitious root formation. The higher concentrations of auxin in the basal portion may be partially responsible for that portion of the hypocotyl producing the greatest number of primordia. In addition to auxins, other factors such as wound ethylene and lowered cytokinin levels caused by excision of the original root system cuttings must also be important.     

Cytokinin receptors are required for normal development of auxin-transporting vascular tissues in the hypocotyl but not in adventitious roots

Plants alter the architecture of their root systems to adapt to the environment by modulating post-embryonic (lateral and adventitious) root formation and growth. To understand better the genetic basis of this regulation, we screened ethylmethane sulfonate-mutagenized lines of Arabidopsis thaliana for adventitious rooting mutants. One mutant showed retardation of the primary root growth, no production of lateral roots and enhanced formation of adventitious roots. Mapping and genetic complementation revealed that this mutant named wooden leg-3 (wol-3) was an allele of ARABIDOPSIS HISTIDINE KINASE 4 (AHK4), a locus known to encode a cytokinin receptor. Although the vascular system of the primary root and hypocotyl in the wol-3 mutant was aborted, that of the adventitious roots was normally developed. In the hypocotyl of the wol-3 mutant, auxin signals accumulated around the aborted vascular system. The application of auxin to primary roots induced lateral root formation in the wol-3 mutant. Transport of radiolabeled auxin from the top of the hypocotyl to the primary root was inhibited in wol-3. Although only a single amino acid alteration had occurred in AHK4, the root morphology in the wol-3 mutant was quite similar to that in the ahk2 ahk3 ahk4 triple mutant, which is a loss-of-function mutant of the three cytokinin receptors. This implies that the functional disturbance of AHK4 affects the function of the other receptors. Our results suggest that cytokinin receptors are necessary for the formation of auxin-transporting vascular tissues in the hypocotyl, but not in adventitious roots.     

Auxin and Ethylene-stimulated Adventitious Rooting in Relation to Tissue 9

We have previously shown that both endogenous auxin and ethylenepromote adventitious root formation in the hypocotyls of derootedsunflower (Helianthus annuus) seedlings. Experiments here showedthat promotive effects on rooting of the ethylene precursor,1-aminocyclopropane-l-carboxylic acid (ACC) and the ethylene-releasingcompound, ethephon (2-chloro-ethylphosphonic acid), dependedon the existence of cotyledons and apical bud (major sourcesof auxin) or the presence of exogenously applied indole-3-aceticacid (IAA). Ethephon, ACC, aminoethoxyvinylglycine (an inhibitorof ethylene biosynthesis), and silver thiosulphate (STS, aninhibitor of ethylene action), applied for a length of timethat significantly influenced adventitious rooting, showed noinhibitory effect on the basipetal transport of [³H]IAA. Theseregulators also had no effect on the metabolism of [³H]IAA andendogenous IAA levels measured by gas chromatography-mass spectrometry.ACC enhanced the rooting response of hypocotyls to exogenousIAA and decreased the inhibition of rooting by IAA transportinhibitor, N-1-naphthylphthalamic acid (NPA). STS reduced therooting response of hypocotyls to exogenous IAA and increasedthe inhibition of rooting by NPA. Exogenous auxins promotedethylene production in the rooting zone of the hypocotyls. Decapitationof the cuttings or application of NPA to the hypocotyl belowthe cotyledons did not alter ethylene production in the rootingzone, but greatly reduced the number of root primordia. We concludethat auxin is a primary controller of adventitious root formationin sunflower hypocotyls, while the effect of ethylene is mediatedby auxin. Key words: Auxin, ethylene, adventitious rooting, sunflower     

ADVENTITIOUS ROOT DEVELOPMENT FROM THE SEEDLING HYPOCOTYL OF LYCOPERSICON ESCULENTUM

Tomato seedlings five through ten days old were used for this investigation. Adventitious roots were initiated from the pericycle of the tomato hypocotyl. The position of adventitious root development was irregular in the rhizogenic hypocotyl; however, the cellular pattern of individual root development was very regular. Four layers of pericycle derivatives participated in root histogenesis and a bi- or triseriate endodermal cover was derived from the endodermis. Fluorescent microscopy showed that Casparian strips on the meristematic endodermal cell walls were not removed biochemically but were displaced around the root primordium by anticlinal divisions and cell enlargement. Casparian strips were not synthesized by endodermal cover cells. The emergent root had a typical three tiered or closed pattern of apical organization, and quiescent centers were present in all emergent roots longer than 0.5–0.6 cm.     

Strigolactones suppress adventitious rooting in Arabidopsis and pea

Adventitious root formation is essential for the propagation of many commercially important plant species and involves the formation of roots from nonroot tissues such as stems or leaves. Here, we demonstrate that the plant hormone strigolactone suppresses adventitious root formation in Arabidopsis (Arabidopsis thaliana) and pea (Pisum sativum). Strigolactone-deficient and response mutants of both species have enhanced adventitious rooting. CYCLIN B1 expression, an early marker for the initiation of adventitious root primordia in Arabidopsis, is enhanced in more axillary growth2 (max2), a strigolactone response mutant, suggesting that strigolactones restrain the number of adventitious roots by inhibiting the very first formative divisions of the founder cells. Strigolactones and cytokinins appear to act independently to suppress adventitious rooting, as cytokinin mutants are strigolactone responsive and strigolactone mutants are cytokinin responsive. In contrast, the interaction between the strigolactone and auxin signaling pathways in regulating adventitious rooting appears to be more complex. Strigolactone can at least partially revert the stimulatory effect of auxin on adventitious rooting, and auxin can further increase the number of adventitious roots in max mutants. We present a model depicting the interaction of strigolactones, cytokinins, and auxin in regulating adventitious root formation.     

Regulatory role of auxin in adventitious root formation in two species of Rumex,differing in their sensitivity to waterlogging

Adventitious rooting in Rumex plants, in which the root systems were in hypoxic conditions, differed considerably between two species. R. palustris, a species from frequently flooded river forelands, developed a large number of adventitious roots during hypoxia, whereas adventitious root formation was poor in R. thyrsiflorus, a species from seldom flooded dykes and river dunes. Adventitious rooting could also be evoked in aerated plants of both species by application of auxin (1-naphthaleneacetic acid or indoleacetic acid) to the leaves. The response to auxin was dose-dependent, but even high auxin doses could not stimulate R. thyrsiflorus to produce as many adventitious roots as R. palustris. Consequently, the difference between the species in the amount of adventitious root formation was probably genetically determined, and not a result of a different response to auxin. A prerequisite for hypoxia-induced adventitious root formation is the basipetal transport of auxin within the shoot, as specific inhibition of this transport by N-1-naphthylphthalamic acid severely decreased the number of roots in hypoxia-treated plants. It is suggested that hypoxia of the root system causes stagnation of auxin transport in the root system. This can lead to an accumulation of auxin at the base of the shoot rosette, resulting in adventitious root formation.     

The Effects of Ascorbate on Root Regeneration in Seedling Cuttings of Tomato

The changes in ascorbate (ASC) and dehydroascorbate (DHA) levels and the activities of ascorbate metabolising enzymes were examined during adventitious root formation in cuttings of tomato (Lycopersicon esculentum Mill. cv. Paw) seedlings. The effects of ASC, DHA and the immediate ascorbate precursor – galactono-γ-lactone (GalL) supplemented to the culture medium on the rooting response, ascorbate content and the activities of the ASC-metabolising enzymes were also investigated. The cuttings treated with abovementioned compounds formed more roots then control plants. However, in contrast to the number of regenerated organs, the elongation of newly formed roots was markedly inhibited. Treatment with auxin (IAA) resulted in a similar phenotype. The inhibitor of auxin polar transport-TIBA (2,3,5-triiodobenzoic acid) effectively blocked rooting. The inhibitory effect of TIBA was reversed by auxin and ASC treatments, while DHA and GalL were ineffective. Both auxin and ASC stimulated cell divisions in an area of pericycle layer of TIBA-treated rooting zones, that enabled cuttings to form roots in the presence of the inhibitor of auxin polar transport. It has been found that the first stages of rooting, preceding the emergence of roots, are accompanied by an increase in endogenous content of ASC with a peak in the 3rd day of rooting. Subsequent stages, when elongation of newly formed roots occurs, are characterised by low level of ASC. The activities of the ascorbate peroxidase (APX), ascorbate oxidase (AOX), ascorbate free radical reductase (AFRR) and dehydroascorbate reductase (DHR) increased in the first 3 days of root formation. The initial period of rooting was also accompanied by the increase of the hydrogen peroxide content and the activities of catalase (CAT) and guaiacol peroxidase (GPX) in the rooting zones. IAA, ASC, DHA as well as Gal stimulated the APX activity, however the rise of the enzyme's activity induced by ASC, DHA and Gal was reversed by TIBA, which was found to inhibit APX. Only exogenous IAA was able to maintain the high level of APX activity in the TIBA-treated cuttings. AOX was strongly affected by ASC and GalL – treatments, its activity increased in the cuttings grown on the media containing ASC in the absence as well as in the presence of TIBA. On the other hand, GalL-dependent stimulation of its activity was suppressed if TIBA was present in a rooting medium.