Aeroponics for adventitious rhizogenesis in evergreen haloxeric tree <Emphasis Type="Italic">Tamarix aphylla</Emphasis> (L.) Karst.: influence of exogenous auxins and cutting type

Tamarix aphylla (L.) Karst., a drought resistant halophyte tree, is an agroforestry species which can be used for reclamation of waterlogged saline and marginal lands. Due to very low seed viability and unsuitable conditions for seed germination, the tree is becoming rare in Indian Thar desert. Present study concerns the evaluation of aeroponics technique for vegetative propagation of T. aphylla. Effect of various exogenous auxins (indole-3-acetic acid, indole-3-butyric acid, naphthalene acetic acid) at different concentrations (0.0, 1.0, 2.0, 3.0, 5.0, 10.0 mg l^?1) was examined for induction of adventitious rooting and other morphological features. Among all three auxins tested individually, maximum rooting response (79%) was observed with IBA 2.0 mg l^?1. However, stem cuttings treated with a combination of auxins (2.0 mg l^?1 IBA and 1.0 mg l^?1 IAA) for 15 min resulted in 87% of rooting response. Among three types of stem cuttings (apical shoot, newly sprouted cuttings, mature stem cuttings), maximum rooting (~ 90%) was observed on mature stem cuttings. Number of roots and root length were significantly higher in aeroponically rooted stem cuttings as compared to stem cuttings rooted in soil conditions. Successfully rooted and sprouted plants were transferred to polybags with 95% survival rate. This is the first report on aeroponic culture of Tamarix aphylla which can be utilized in agroforestry practices, marginal land reclamation and physiological studies.     

INITIATION AND DEVELOPMENT OF ROOTS IN JUVENILE AND MATURE LEAF BUD CUTTINGS OF FICUS PUMILA L.

Adventitious root formation (ARF) was studied in woody leaf bud cuttings of Ficus pumila L., creeping fig. Juvenile cuttings rooted easily, whereas only mature cuttings treated with indole-3-butyric acid (IBA) attained any rooting success. In the rooting process, both juvenile and mature material exhibited dedifferentiation of phloem ray parenchyma, root initial formation, primordia differentiation, and root elongation. The early stages of adventitious rooting were most critical since few primordia were observed in mature controls. The stages leading up to root primordia differentiation and elongation occurred more rapidly in IBA-treated juvenile vs. mature cuttings; however, time differences in both types between first observable roots and maximum rooting were comparable. Root primordia differentiated from basal callus of some cuttings, but neither these nor the few primordia in mature controls elongated into well-developed roots. Anatomical differences between the juvenile and mature material did not account for rooting disparity, nor did presence of perivascular fibers, sclereids, and laticifers retard rooting.     

Quantification of IAA Metabolites in the Early Stages of Adventitious Rooting Might Be Predictive for Subsequent Differences in Rooting Response

Stock mother plants have gained importance in the process of adventitious rooting of woody plants in recent years. The present study reveals the role of the cutting position from a stock mother plant for subsequent rooting. Cuttings of Prunus subhirtella Miq. var. Autumnalis which originated from suckers at the bottom of a tree developed a rooting system of better quality (rooted cutting without callus formation, more main roots) compared to cuttings which originated from shoots at the top of a tree. The latter accumulated significantly more indole-3-acetic acid (IAA) with the highest value of 25.37 μg g^?1 FW on the severance date. These cuttings also contained more indole-3-acetyl-aspartate (IAA-Asp) on the second day after severance with the highest value of 4875.95 μg g^?1 FW compared to cuttings from the bottom-deriving suckers. The latter metabolised IAA primarily via 2-oxindole-3-acetic acid (oxIAA) and indole-3-methanol because the concentrations of these compounds increased at the base of these cuttings. The highest concentration of oxIAA, 8.3 mg ekv. IAA g^?1 FW, was measured 1 h after severance in cuttings from the bottom-derived suckers. With 590.5 ng ekv IAAg^?1 FW, the indole-3-methanol values were also significantly higher in the cuttings from the bottom shoots compared with cuttings from the top of the tree.     

Synergistic interaction between coumarin 1,2-benzopyrone and indole-3-butyric acid in stimulating adventitious root formation in Vigna radiata (L.) Wilczek cuttings: I. Endogenous free and conjugated IAA and basic isoperoxidases

Cuttings from 7-day-old Vigna radiata seedlings were treated for 24 h with various concentrations of coumarin and/or indole-3-butyric acid (IBA), applied either alone or in combination, in order to stimulate adventitious root formation (ARF). The effects of treatment on endogenous free and conjugated indole-3-acetic acid (IAA), basic peroxidase (basic PER) activity and its isoperoxidases analysis and their relation to ARF were then investigated at the potential rooting sites during the first 96 h after application. Simultaneously, combined treatments acted synergistically in inducing more adventitious roots in treated cuttings than in those treated with coumarin or IBA individually, as compared with the control. Endogenous free IAA increased transiently in treated cuttings as compared with the control and the maximum increase occurred with the combined treatment. This suggests that coumarin and IBA may act synergistically in increasing the endogenous free IAA level during the induction phase of rooting to initiate more roots. Likewise, higher level of conjugated IAA was also found in treated cuttings than in untreated ones, during the primary events of ARF, with the maximum level occurring in the combined treatment. Comparison of the dynamics of conjugated IAA and activity of basic PERs led to conclusion that the former but not the latter is responsible for downregulation of endogenous IAA levels significantly during the primary events of ARF. A sharp increases in basic PERs occurred during the secondary events of ARF, suggesting their role in root initiation and development rather than root induction.     

Effects of combinational treatment with ethephon and indole-3-butyric acid on adventitious rooting of <Emphasis Type="Italic">Pinus thunbergii</Emphasis> cuttings

Adventitious rooting is essential for cutting propagation of pine wilt-resistant Pinus thunbergii. To examine a variety of adventitious rooting potentials among donor plants, cuttings were taken from 31 seedlings within a half-sib family. Rooting abilities of cuttings from each seedling ranged from 0 to 100%. When 11 ortets and 11 ramets (clonally propagated from each ortet) were used as donor plants, there was a positive correlation between rooting abilities of cuttings from ortets and ramets, suggesting that adventitious rooting is dependent on genetic factors in the donor plants. To promote adventitious rooting of cuttings by hormonal treatment, we examined the effect of soaking time in Oxyberon (19.7 mM indole-3-butyric acid (IBA) solution) on rooting. Ten minutes was the best soaking time for rooted cuttings to produce more adventitious roots without impairing normal growth. When cuttings were soaked in Ethrel diluent (69.2 μM ethephon) for 24 h before soaking in Oxyberon for 10 min, a significantly higher rooting ability was observed than those soaked in Oxyberon alone. Ethrel on its own barely affected rooting ability. The positive effect of the combinational treatment was confirmed in a similar experiment using authentic ethephon and IBA instead of Ethrel and Oxyberon. When cuttings were soaked in a mixture of ethephon and silver thiosulfate (STS), an ethylene action inhibitor, before IBA-soaking, the effect was partially diminished compared with combinational treatment without STS. These findings suggest that ethylene action caused by ethephon treatment promotes IBA-mediated adventitious rooting of P. thunbergii cuttings.     

Conversion of Indole-3-Butyric Acid to Indole-3-Acetic Acid in Shoot Tissue of Hazelnut (<Emphasis Type="Italic">Corylus</Emphasis>) and Elm (<Emphasis Type="Italic">Ulmus</Emphasis>)

Indole-3-butyric acid (IBA) is an endogenous compound that appears to regulate both lateral and adventitious root formation in many plant species and is also the auxin most available commercially for application to promote rooting. IBA is converted to indole-3-acetic acid (IAA) by β-oxidation in the peroxisomes. This process has been observed in a number of plant species and has been shown to be critical for normal root development in response to treatment with IBA. In this study, we investigated this process in hybrid hazelnut (Corylus americana × C. avellana), American elm (Ulmus americana), and Cathedral hybrid elm (U. pumila × U. davidiana var. japonica ‘Cathedral’), in which adventitious rooting is a major bottleneck for vegetative propagation, and the efficacy of IBA treatment is highly variable across different cultivars and at different collection times. Using differentially stable isotope-labeled IBA and IAA tracer and internal standard, respectively, and using gas chromatography coupled with selected reaction monitoring mass spectrometry, IBA-derived IAA was measured in shoot tissue treated with stable isotope-labeled IBA. In elm, higher levels of IBA-to-IAA conversion were generally observed in cultivars which formed adventitious roots most easily in softwood stem cutting trials. IBA-to-IAA conversion was observed in hazelnut genotypes with different rooting abilities and suggested a complex relationship exists between IBA conversion and root organogenesis. In both hazelnut and elm, endogenous free IAA levels were not significantly different across the genotypes examined. High rates of root formation is a key trait for establishment of large-scale production systems. Screening for optimal rates of IBA-to-IAA conversion may facilitate selection against genotypes which respond poorly to exogenous IBA and are thus difficult to propagate using hormone treatment.     

Adventitious rooting adjuvant activity of 1,3-di(benzo[d]oxazol-5-yl)urea and 1,3-di(benzo[d]oxazol-6-yl)urea: new insights and perspectives

Here we report new insights on the adventitious rooting adjuvant activity of 1,3-di(benzo[d]oxazol-5-yl)urea (5-BDPU) and 1,3-di(benzo[d]oxazol-6-yl)urea (6-BDPU), both symmetrically substituted urea derivatives that do not show either auxin- or cytokinin-like activity per se. Our data demonstrate that these synthetic molecules enhance adventitious rooting in distantly-related herbaceous and woody species, in the presence of endogenous or exogenous auxin. For the first time, we report that BDPUs enhance adventitious rooting in the presence of either indole-3-butyric acid (IBA) or 1-naphtalene acetic acid and that their optimal concentration depends on the strength of the exogenous auxin. Trying to understand the mode of action of BDPUs, we also show that their adventitious rooting adjuvant activity correlates with high mRNA levels of auxin-responsive genes related to the adventitious rooting process at the very early stages of adventitious rooting, before the activation of cell divisions in pine hypocotyls cuttings. The high mRNA levels are measured in the presence of low auxin concentrations and BDPUs. The mRNA levels quantified in these conditions are similar to those measured in the presence of high auxin concentrations but in the absence of BDPUs. In addition, the spatial distribution of endogenous auxin is localized in globular-shaped structures of cell divisions located centrifugal to the resin canals, at the positions of adventitious root formation, in the presence of urea derivatives and IBA after 6 days of the root induction process.     

Differences in endo/exogenous auxin profile in cuttings of different physiological ages

The process of physiological ageing in woody plants is a very important factor influencing adventitious rooting. However, there is a lack of knowledge of biochemical backgrounds triggering ageing and consequently, rhizogenesis. Experiments with Prunus subhirtella ‘Autumnalis’ leafy cuttings of three different physiological ages (adult (over 40-year-old stock plants), semi-adult (5-year-old cutting plants) and juvenile (5-year-old in vitro plants)) were conducted in 2009. Half of the cuttings were banded ca. 3 cm above the bottom of the cutting with aluminum wire prior to insertion into the substrate to block the polar auxin transport. IBA, which was exogenously applied to the cuttings, could only be detected in the base of the cuttings on the first day after severance. Juvenile cuttings tended to have the highest values, but the effect was age specific. Later, the detection was not possible, regardless of the age. The IAA profile in cutting bases was similar for all physiological ages, reaching the peak on the first day after severance. Juvenile cuttings, in which the stems had been banded before insertion, contained more IAA in their bases on day 1 compared to the stems, which were not banded. These cuttings presumably transported absorbed auxin mainly via phloem, and not via mass flow like semi-adult and adult cuttings, where IAA concentrations were similar or even greater in non-banded cuttings compared to banded ones. These cuttings also tended to exhibit the best rooting results. The IAA-Asp accumulation was especially strong in adult cuttings, which contained significantly more aspartate on the first and third days after severance when compared with semi-adult and juvenile cuttings.     

Ethylene and auxin-ethylene interaction in adventitious root formation in mung bean (Vigna radiata) cuttings

The role of ethylene in adventitious root formation and its involvement in auxin-induced rooting were investigated in cuttings ofVigna radiata (L.). Treatment with 30 M indole-3-acetic acid (IAA) for 24 h slightly inhibited rooting, whereas the same concentration of indole-3-butyric acid (IBA) significantly stimulated it. Ethylene derived from 1-aminocyclopropane-1-carboxylic acid (ACC) increased the number of adventitious roots but inhibited their emergence and elongation. Endogenous levels of ethylene, ACC, and malonyl-ACC (MACC) were initially higher in cuttings treated with IAA. This trend was quickly reversed, and cuttings, particularly hypocotyls, treated with IBA produced higher levels of ethylene and had more ACC and MACC during most of the rooting process. Aminoethoxyvinylglycine significantly inhibited rooting, but its inhibitory effect could not be reversed by ACC. The data suggest that the stimulating effect of IBA on rooting is closely associated with its induction of ACC and ethylene biosynthesis.     

Root Development Enhanced by Using Indole-3-butyric Acid and Naphthalene Acetic Acid and Associated Biochemical Changes of In Vitro Azalea Microshoots

Based on the importance of producing in vitro adventitious roots, this study was carried out to investigate the effects of indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) at a concentration of 2 mg L^?1 on the formation of adventitious roots of azalea and their impact on biochemical changes and endogenous hormones. The rooting percentage, root number, and root length were increased in the microshoots of both studied cultivars (‘Mingchao’ and ‘Zihudie’) when the growth medium was supplemented with IBA. Additionally, peroxidase, indole acetic acid oxidase, hydrogen peroxide, and soluble protein contents were improved in both cultivars by auxin treatments especially during the first 7 days of the rooting period. However, application of IBA and NAA increased catalase and polyphenol oxidase in both cultivars during the first 14 and 28 days of culture. The increase in endogenous indole acetic acid (IAA) levels was accompanied by low activity of IAAO during most periods of root induction of microshoots in all treatments. Endogenous gibberellic acid levels were increased after 7 days of culture and then increased again after 28 days of culture. In contrast, the levels of endogenous zeatin riboside and isopentenyl adenosine were decreased with auxin treatments in the first period of the rooting process and then increased after 21 and 28 days of culture. The present study demonstrated that IBA at a concentration of 2 mg L^?1 has a strong effect on azalea rooting. Moreover, the efficiency of IBA and NAA effects on biochemical changes during adventitious root induction was investigated, which may provide new horizons of in vitro rooting production and provide valuable information for the micropropagation of Rhododendron plants.     

Adventitious rooting performance in micropropagated Cornus mas

Axillary buds sampled from a mature 27-year-old Cornus mas cv. Macrocarpa were grown in vitro on modified woody plant medium (WPM). Adventitious rooting performance of microshoots was assayed on half-strength WPM supplemented with 1-naphthaleneacetic acid (NAA) or indole-3-butyric acid (IBA) under various pH. NAA induced significantly higher rooting frequencies than IBA. The pH of 6.8 inhibited rooting, and differentiated roots were extremely thick and fragile. The highest rooting frequency was recorded on half-strength WPM supplemented with 5.37 µM NAA at the pH value adjusted to 6.2 (73 % of rooted shoots). In the presence of IBA, the formation of adventitious roots was observed only in the basal part of the microshoot dipped into rooting medium. In the case of NAA, however, adventitious roots arose also from the parts of microshoots that were not in contact with medium. The growth of aerial roots was always positively gravitropic. The nuclear microsatellite Cf-G17 gave a monomorphic fingerprinting pattern across the mother shrub and micropropagated plantlets. Acclimatized plants did not show any visually detectable morphological variation and the aerial adventitious root formation was no longer observed.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated genetic transformation of <Emphasis Type="Italic">Acacia mangium</Emphasis>

A protocol was developed for Agrobacterium-mediated genetic transformation of Acacia mangium using rejuvenated shoots as the explant. Axillary buds and shoot apices of adult trees were rejuvenated by culturing them on Murashige and Skoog (MS) medium, and stem segments of rejuvenated shoots were co-cultured with Agrobacterium tumefaciens strain LBA4404 harbouring binary vector pBI121. The selection for transgenic shoots was performed through five consecutive steps on MS medium supplemented with 1.0 mg/l thidiazuron, 0.25 mg/l indole-3-acetic acid and different concentrations of geneticin (G418; 12–30 mg/l) and timentin (T; 50–300 mg/l) in the following order: 12 mg/l G418 and 300 mg/l T for 30 days, 20 mg/l G418 and 200 mg/l T for 60 days, 30 mg/l G418 and 100 mg/l T for 30 days, 12 mg/l G418 and 50 mg/l T for 30 days, and finally 15 mg/l G418 and 5 mg/l gibberellic acid (GA₃) for 60 days. Thirty-four percent of the stem segments produced resistant multiple adventitious shoot buds, of which 30% expressed the β-glucuronidase gene. The shoot buds were subjected to repeated selection on MS medium supplemented with 2.0 mg/l 6-benzylaminopurine, 2.5 mg/l GA₃ and 20 mg/l G418. Transgenic plants were obtained after rooting on half-strength MS medium supplemented with 2.0 mg/l α-naphthaleneacetic acid, 0.1 mg/l kinetin and 20 mg/l G418. Genomic Southern blot hybridization confirmed the incorporation of the NPTII gene into the host genome.     

Influence of the irradiance on phenols content and rooting of Ilex paraguariensis cuttings collected from adult plants

The influence of irradiance on phenolics contents and rooting of Ilex paraguariensis cuttings was studied. Results of the first experiment with stock plants under controlled-irradiance conditions show that when the irradiance level increased from 1.5 to 100 % PPFD, the oxidation of cuttings raised from 19 ± 11 to 88 ± 4 % (r ² = 0.64). At the same time, a strong correlation was observed between total phenolics content and irradiance (r ² = 0.7). In consequence, adventitious rooting diminished from 67 ± 5 to 3 ± 3 % under full radiation (r ² = 0.7). In the second experiment with stock plants subjected to field conditions, the results showed that the rooting process is strongly affected by the genotype (P < 0.0001), while the statistical analysis did not show a correlation between rooting and age of the donor plant. Season had a variable effect and depends on genotype. Although we did not find correlations between the rooting ability and the canopy structure of the stock plants, the position of the branches in the mother plant affected rooting and depended on season in addition to genotype. Concomitantly, the levels of soluble phenolics compounds were higher from leaves subjected to high-irradiance conditions than samples collected from inner canopy; which was coincident with the pattern of cuttings oxidation. In conclusion, our results provide evidences which support the hypothesis that the physiological status of the stock plant at the time that cuttings are excised is of utmost importance for the subsequent rooting of I. paraguariensis cuttings. The influence on soluble phenolics content of different irradiances given to the stock plants negatively affect the rooting process since the product of its oxidation cause the browning and death of the cuttings.     

Shoot RNA, cambrial activity and indolebutyric acid effectivity in seasonal rooting of juvenile and mature Ficus pumila cuttings

The seasonal influence on adventitious root formation was studied in woody leaf bud cuttings of Ficus pumila L., creeping fig. Juvenile cuttings rooted easily, whereas only mature cuttings treated with indolebutyric acid (IBA) exceeded 30% rooting. Greater rooting occurred in IBA-treated juvenile and mature cuttings than controls, regardless of the month each experiment was initiated. Seasonal changes influenced rooting in all treatments except IBA treated juvenile cuttings where percentage rooting was not affected. Higher vascular cambial activity and shoot RNA levels occurred in juvenile and mature forms during peak rooting periods. Highest RNA was recorded with juvenile materials during maximum rooting periods, while lowest RNA was observed in mature shoots during low rooting intervals.     

Reduced irradiance and applied auxin influence carbohydrate relations in Pinus banksiana cuttings during propagation

Untreated and indole-3-butyrie acid-treated (IBA) cuttings from 90-day-old Pinus banksiana Lamb, stock plants were propagated under normal greenhouse irradiance (max. 900 $$mol m^-2 s^-1) and shade (max. 120 $$mol m^-2 s^-1) to determine effects on adventitious rooting and on reducing sugar and starch concentrations in needles and basal stems. In one experiment, cuttings were assessed at days 15 and 25 of propagation for basal 1-cm stem fresh weight, proportion rooted, number of roots and longest root length. In a second experiment with cuttings, basal 1-cm stem fresh weight and concentrations of reducing sugar and starch in needles and basal stems were measured each day for the first 10 days of propagation. Carbohydrate measurements were also made for seedling stock plants as controls for the second experiment. Carbohydrate data for cuttings were primarily evaluated based on net (cutting minus seedling) concentrations, to correct for changes in cuttings not related to adventitious rooting. Increase of basal stem fresh weight and rooting of cuttings, based on all measured variables, occurred in the order: light + IBA > light > shade + IBA > shade. The best rooting required the greater irradiance. Compared to results from cuttings in the light, shading resulted in lesser accumulations of reducing sugars and starch in needles and basal stems. Reducing sugar: starch concentration ratios were significantly greater in shade- vs light-propagated cuttings, IBA treatment did not offset the effects of shade on rooting or on reducing sugar and starch concentrations or ratios. Overall, the results suggested that decreased reducing sugar and starch concentrations and/or their increased ratios are associated with shade-induced poor rooting of P. banksiana cuttings.     

Auxins or Sugars: What Makes the Difference in the Adventitious Rooting of Stored Carnation Cuttings?

Cold storage of cuttings is frequently applied in the vegetative propagation of ornamental plants. Dianthus caryophyllus was used to study the limiting influences of auxin and sugars on adventitious root formation (ARF) in cuttings stored at 5°C. Carbohydrate levels during storage were modulated by exposing cuttings to low light or darkness. The resulting cuttings were treated (or not) with auxin and planted, and then ARF was evaluated. Carbohydrate levels in the cuttings were monitored and the influence of light treatment on indole-3-acetic acid (IAA) and zeatin (Z) in the basal stem was investigated. Dark storage for up to 4 weeks increased the percentage of early rooted cuttings and the final number and length of adventitious roots, despite decreased sugar levels in the stem base. Light during cold storage greatly enhanced sugar levels, particularly in the stem base where the Z/IAA ratio was higher and ARF was lower than observed in the corresponding dark-stored cuttings. Sugar levels in nonstored and dark-stored cuttings increased during the rooting period, and auxin application enhanced the accumulation of sugars in the stem base of nonstored cuttings. Auxin stimulated ARF most strongly in nonstored, less so in light-stored, and only marginally in dark-stored cuttings. A model of auxin-sugar interactions in ARF in carnation is proposed: cold storage brings forward root induction and sink establishment, both of which are promoted by the accumulation of auxin but not of sugars, whereas high levels of sugars and probably also of cytokinins act as inhibitors. Subsequent root differentiation and growth depend on current photosynthesis.     

Rapid multiplication of Dalbergia sissoo Roxb.: a timber yielding tree legume through axillary shoot proliferation and ex vitro rooting

An efficient and improved method for in vitro propagation of mature tree of Dalbergia sissoo, an ecologically and commercially important timber yielding species, has been developed through axillary shoot proliferation. Bud breaking occurred from nodal shoot segments derived from rejuvenated shoots produced during early spring from a 20–25-year-old lopped tree, on MS medium containing 8.88 μM benzylaminopurine (BAP). Multiple shoots differentiated (20–21shoots/node) on re-culture of explants on half-strength agar gelled amended MS medium with a combination of 2.22 μM of BAP and 0.002 μM of thidiazuron (TDZ) with 1.0 mM each of Ca(NO₃)₂, K₂SO₄, KCl, and NH₄(SO₄)₂. The maximum shoot multiplication (29–30 shoots/node) was achieved on subculturing in the above mentioned but liquid medium. Furthermore, the problem of shoot tip necrosis and defoliation observed on solid medium were overcome by the use of liquid medium. Ex vitro rooting was achieved on soilrite after basal treatment of microshoots with 984 μM of indole-3-butyric acid (IBA) for 2 min. About 90 % microshoots were rooted on soilrite within 2–3 weeks under the greenhouse conditions. From 20 nodal shoot segments, about 435 hardened plants were acclimatized and transplanted. This is the first report for rapid in vitro propagation of mature trees of D. sissoo on liquid medium followed by ex vitro rooting.     

Evaluation of aeroponics for clonal propagation of Caralluma edulis,Leptadenia reticulata and Tylophora indica – three threatened medicinal Asclepiads

The present study explores the potential of aeroponic system for clonal propagation of Caralluma edulis (Paimpa) a rare, threatened and endemic edible species, Leptadenia reticulata (Jeewanti), a threatened liana used as promoter of health and Tylophora indica (Burm.f.) Merill, a valuable medicinal climber. Experiments were conducted to asses the effect of exogenous auxin (naphthalene acetic acid, indole-3-butyric acid, indole-3-acetic acid) and auxin concentrations (0.0, 0.5, 1, 2, 3, 4 or 5gl⁻¹) on various root morphological traits of cuttings in the aeroponic chamber. Amongst all the auxins tested, significant effects on the length, number and percentage of rooting was observed in IBA treated nodal cuttings. Cent per cent of the stem cuttings of C. edulis rooted if pre-treated with 2.0 gl⁻¹ of IBA for 5 min while 97.7 % of the stem cuttings of L. reticulata and 93.33 % of stem cuttings of Tylophora indica rooted with pre-treatment of 3.0 gl⁻¹ of IBA for 5 min. Presence of at least two leaves on the nodal cuttings of L. reticulata and T. indica was found to be a prerequisite for root induction. In all the species, the number of adventitious roots per cutting and the percentage of cuttings rooted aeroponically were significantly higher than the soil grown stem cuttings. Shoot growth measured in terms of shoot length was significantly higher in cuttings rooted aeroponically as compared to the cuttings rooted under soil conditions. All the plants sprouted and rooted aeroponically survived on transfer to soil. This is the first report of clonal propagation in an aeroponic system for these plants. This study suggests aeroponics as an economic method for rapid root induction and clonal propagation of these three endangered and medicinally important plants which require focused efforts on conservation and sustainable utilization.