Shoot Multiplication Rate Research Articles

The effect of different light treatments on morphogenesis, phenolic compound accumulation and antioxidant potential of Dracocephalum forrestii transformed shoots cultured in vitro.

The aim of this study was to evaluate the effects of wavelengths of light emitted from LEDs on cultured in vitro transformed shoots of Dracocephalum forrestii. The shoots were grown on MS agar medium with 0.5mg/l BPA (N-benzyl-9-(tetrahydropyranyl)-adenine) and 0.2mg/l IAA (indole-3-acetic acid) under four light environments: blue, red, red/blue (7:3) and white (control). After four weeks of culture, shoot multiplication rate, biomass and morphology were evaluated, as well as bioactive phenolic content, antioxidant capacities and antioxidant enzyme activities. The hydromethanolic extracts from shoots were analyzed using UHPLC method, and antioxidant potential was evaluated using radical scavenging (1,1-diphenyl-2-picrohydrazyl and superoxide anion), and ferric reducing antioxidant power (FRAP), and enzymatic methods, i.e. sodium dismutase (SOD), catalase (CAT) and peroxidase (POD) activity. It was found that the blue and red/blue light had the strongest effect on morphogenesis and shoot propagation; in these conditions, more than five new shoots were obtained per explant. The blue light cultures demonstrated the highest fresh (0.41g/tube FW) and dry weights (0.045g/tube DW), the highest levels of polyphenols (99.7mg/g DW), i.e. almost three times greater than under white light (35.4mg/g DW), as well as the highest antioxidant potential. Therefore, LED culture appears to be a beneficial strategy for enhancing the production of the medicinal value of transformed D. forrestii shoot culture.

Gamma irradiations induced morphological and biochemical variations in in vitro regenerated ginger (Zingiber officinale rosc.)- an invaluable medicinal spice

Purpose To evaluate the effect of gamma irradiations on morphological and biochemical variations of in vitro shoots, regenerated plants and rhizomes of ginger (Zingiber officinale Rosc.) var. Himgiri. Materials and methods In vitro established shoot cultures were treated with different doses of gamma irradiations (10–100 Gy). Nonirradiated shoots were used as controls. Radio sensitivity of shoots and in vitro growth parameters were recorded. Surviving shoots along with controls were multiplied, rooted and hardened. Irradiation effect on chromosomes was evaluated by comparing with controls. Various morphological and biochemical observations were recorded in regenerated plants and rhizomes and compared to controls. Results Irradiated shoots showed decline in survival percentage (95% in 10 Gy to 12.33% in 100 Gy) with increase in dose rate after 4 weeks of irradiation. Shoot survival significantly decreased with irradiation dose rate above 20 Gy. Shoot multiplication rate showed an increase from 1:2 in 1st subculture to 1:9 after 5th subculture, in 10 Gy irradiated cultures with 4.5 cm average length of shoots and 8.19 number of leaves after 5th subculture. Average rooting showed an increase from 15.55% after 2nd subculture to 100% after 5th subculture, in 10 Gy irradiated shoots; however, no multiplication and rooting was observed in higher doses. In vitro rooted shoots were subjected to hardening with 100 percent survival in a mixture comprised of soil, cocopeat and FYM. One-year-old hardened plants when observed for morphological variations showed nonsignificant variations in comparison to controls. Rhizomes obtained from 10 Gy irradiated plants showed enhanced concentration of 6-gingerol and reduced crude fiber content when compared with controls. Conclusions Gamma irradiation doses up to 10 Gy resulted in nonsignificant phenotypic variations but can positively affect biochemical composition of rhizomes leading to development of biochemically improved mutant lines of ginger with increased 6-gingerol and lowered crude fiber content. Therefore, suggesting the lower doses of gamma irradiations for improvement of biochemical constituents in vegetatively propagated plants.

Development of direct regeneration protocol for mass multiplication of Musa spp. variety Udhayam (Pisang Awak, ABB) using different explants

Musa spp. variety Udhayam (Pisang Awak, ABB) is the first high yielding selection from ICAR-NRCB, Trichy released during 2005. The demand for quality planting material shows an increasing trend because of its higher yield (40%) than the local Karpuravalli. But this variety is highly recalcitrant for shoot tip culture owing to its high phenolic exudation, and very low shoot proliferation rate (<2.0). Therefore, in the present study, attempts were made to develop direct regeneration protocol for the aforementioned variety using various explants like cormlets and male floral hands other than shoot tips. Results revealed that the direct regeneration protocols using cormlets and male floral hands were totally free from latent contamination and recorded high rate of shoot multiplication as against shoot tip explants. Among the three explants used, immature male floral hands showed not only higher multiplication rate under in vitro conditions and also performed better under field conditions compared to shoot tip and cormlet derived plants. The plantlets derived from different explants were found to be true to type as confirmed using ISSR markers. Field performance of the plants derived from various explants indicated that though all are suitable for direct regeneration, male floral hands was superior followed by sucker, shoot tip and cormlets in terms of bunch yield and crop duration. Key message: Immature male flower buds are the best explants for mass multiplication through direct regeneration and commercial exploitation in banana variety Udhayam (Pisang Awak, ABB).

Assessment of In-vitro culture through Nodal explants of Dendrocalamus hamiltonii

The present experimental study was aimed to overcome the traditional methods of propagation that limit the number of propagules by in-vitro regeneration through nodal explants of Dendrocalamus hamiltonii with a comparative study of growth regulators during the shooting and rooting process. Dendrocalamus hamiltonii is distributed from the Himalayas (Nepal) to the northern part of Burma. Collection of explants was done from different selected sites of CPTs. There was the use of HgCl2 and Ca (OCl)2 as sterilizing agents in different concentrations and its effect was visualized during the sprouting stage. Culm explants were cultured in a bottle containing White media (Wm) supplemented with BA and Kinetin for sprouting and IAA, IBA, NAA for rooting. There is also the use of IAA+IBA+NAA in combined form as a supplementary solution 0.1% HgCl2 treatment for 20-minute results into77.80% aseptic buds and 72% bud -break. Among the used growth-hormones, BA with concentration 0.25mg/l and 0.50mg/l respectively were appropriate for shoot-multiplication rate, 4.01±0.3 and 4.3±0.4 were ideal observation incorporation with BA (1.00mg/l) and BA (1.50mg/l) respectively. Maximum sprouting rate14.77±3.37with application of BA (2.00mg/l) and maximum shoot length4.3±0.4 is observed at BA (1.50mg/l). The applications of rooting hormone IAA+IBA+NAA in the concentration of 1.0 mg/l results in 72.5±0.3(rooting) and 11.1±0.3 (av. No. of the root).

An Improved liquid Culture System for Efficient Shoot Multiplication in Aerva lanata (L.) Juss. Ex Schult.

An improved in vitro mass propagation protocol was developed for Aerva lanata using MS liquid medium. The influence of MS medium (solid and liquid) with cytokinin (TDZ and BAP, respectively) were studied for shoot proliferation and growth. The liquid medium perfomed better than solid medium in shoot multiplication. The maximum shoot multiplication rate was (29.37 ± 0.64 shoots per explant), obtained in MS liquid medium which is containing 0.6 mg/l TDZ, 0.3 mg/l NAA and 0.2 mg/l IBA. Different volumes of liquid medium have been used, 30 ml of medium flask showed the maximum number of shoots. Liquid medium is better suited for in vitro propagation of A. lanata since the enhanced multiplication rate was observed with shorter subculture intervals.&#x0D; Plant Tissue Cult. &amp; Biotech. 31(1): 35-42, 2021 (June)

Micropropagation of arrow cane, Gynerium sagittatum (Aubl.) P. Beauv. cv. Criolla, Criolla 1, and Martinera, in a double-phase medium

To evaluate the micropropagation response of arrow cane, Gynerium sagittatum (Aubl.), plants using a double-phase medium in the multiplication stage, explants consisting of stem sections with axillary meristems from cultivars Criolla, Criolla 1, and Martinera were established in vitro in a semisolid medium. Then, they were multiplied using a double-phase medium supplied at several Benzylaminopurine (BAP) concentrations (0.0, 0.5, 1.0, 1.5, and 2.0 mg/L), followed by rooting in a culture medium supplied at several Naphthaleneacetic acid (NAA) concentrations (0.0, 0.5, 1.0, 1.5, and 20 mg/L). Both multiplied unrooted and rooted microshoots were transferred ex vitro. Treatments were distributed with a completely randomized design; data were analyzed with an ANOVA and means separated with Tukey’s test. Explants from Criolla and Martinera cultured with 0.5 mg/L BAP resulted in higher multiplication rates. All microshoots transferred to the rooting medium rooted, although NAA significantly increased the number of roots and reduced root length. Plants from all three cultivars, in vitro rooted or unrooted transferred to ex vitro conditions, showed 100 % survival and adaptation. For Criolla and Martinera, 0.5 mg/L BAP statistically increased shoot multiplication rates and NAA increased adventitious root formation and reduced root length. Plants of all cultivars survived and adapted 100 % to ex vitro conditions.

Comparison of Different Semi-Automated Bioreactors for In Vitro Propagation of Taro (Colocasia esculenta L. Schott).

Taro is important for its nutritional content, medicinal use, and bioethanol production. The aim of the present study was to compare different semi-automated bioreactors (SABs) during in vitro multiplication of C. esculenta. The SABs used were temporary immersion bioreactors (TIBs), SETIS™ bioreactors and ebb-and-flow bioreactors; semi-solid culture medium was used as a control treatment. At 30 d of culture, different developmental variables, determination of chlorophyll, stomatal content, and survival percentage during acclimatization were evaluated. SABs increased the shoot multiplication rate relative to the semi-solid medium; however, the SETIS™ bioreactor showed the highest shoot production, with 36 shoots per explant, and the highest chlorophyll content. The stomatal index was higher in the semi-solid medium compared to the SABs, while the percentage of closed stomata was higher in the SABs than in the semi-solid culture medium. The survival rate during acclimatization showed no differences among the culture systems assessed, obtaining survival rates higher than 99%. In conclusion, the SETIS™ bioreactor showed the highest multiplication rate; however, other bioreactor alternatives are available for semi-automation and cost reduction for micropropagation of C. esculenta.

Development of robust in vitro culture protocol for the propagation of genetically and phytochemically stable plants of Withania somnifera (L.) Dunal (Ashwagandha)

Withania somnifera (L.) Dunal is an important medicinal plant that has gained a lot of attention since ancient times due to its immense pharmaceutical potential. Scientific validations of its therapeutic potential against many diseases have immensely increased its demand in the domestic and international market. Thus, to narrow down the huge gap between its demand and supply, alternative strategies to conventional cultivation are required. In vitro propagation system provides a feasible option for the production of large-scale healthy, genetically and phytochemically uniform W. somnifera plants to boost the herbal industry and facilitate pre-clinical studies. However, the major challenge in in vitro propagation of W. somnifera is to maintain a high rate of shoot multiplication for prolonged periods in cytokinin containing MS medium. In the current investigation, for prolonged maintenance of in vitro shoots, a multi-step protocol involving the rotational subculture of Withania shoots in the auxin-cytokinin containing culture medium has been developed to minimize the adverse effects of cytokinin. In vitro shoots after prolonged subculture were checked for genetic uniformity and stable pharmaceutically important constituents. Furthermore, in vitro rooting was initiated either in an auxin-dependent or auxin-independent manner through modulation of ammonium nitrate strength. Hence, the protocol developed for in vitro propagation of W. somnifera is cost-effective and can be efficiently used for the industrial production of withanolides.

In vitro micropropagation of wild rare plant Rhododendron ledebourii Pojark

Rhododendron ledebourii Pojark. is a highly decorative rare species of the flora of Siberia (Russia) and can be used as a source of biologically active substances, as well as in landscaping. We have optimized the in vitro propagation protocol for this species. Sterilization of annual shoots of field plants with 5% lysoformin-3000 provided 70% aseptic viable explants. The addition of 2 mg L−1 glycine to Anderson’s medium in combination with 8 mg L−1 2-isopentyladenine and 3 mg L−1 indolyl-3-acetic acid stimulated a high multiplication rate and active growth of axillary and adventitious shoots. The adaptation of regenerants in a hydroponic installation containing ¼ of the basic composition of macro- and microsalts according to Murashige and Skoog’s medium promoted the development of powerful roots for subsequent successful acclimatization to ex vitro conditions. This approach ensured the survival rate of 90% microplants.

Micropropagation of banana (Musa spp) using temporary immersion bioreactor system

Banana is an important crop in the tropics which possess the potential for commercial production in Nigeria. Large scale production requires large volume of planting materials which may be difficult to obtain using conventional methods of propagation. Temporary immersion bioreactor system (TIBs) is a cost effective method for micropropagation of plants. The present study was carried out to develop an efficient method for rapid multiplication of banana using temporary immersion bioreactor system (TIBs). Banana microshoots were regenerated from young suckers obtained from field grown plants using conventional plant tissue culture. Microshoots of 2cm length were used as explants for multiplication in temporary immersion bioreactor system. Ten (10) explants were cultured in bioreactor bottles containing Murashinge and Skoog (MS) liquid media supplemented with different concentrations of 6-bezylaminopurine (BAP) with or without 250mg/L Activated Charcoal (AC). Results showed that explants cultured in media supplemented with 2 mg/L or 1mg/L BAP without AC gave the highest shoot multiplication rate of 900% and 800%, respectively compared to hormone free media. Production of competent plants (plants ready for ex vitro establisment) were however, influenced by the presence of AC and the highest percentage of competent plants (80%) were produced when media was fortified with 1mg/L BAP+ 250mg AC. Regenerated plants were successfully established in the field and were morphologically normal and fertile.

Improved protocol for micropropagation of genetically uniform plants of commercially important cardamom (Elettaria cardamomum Maton)

Cardamom (Elettaria cardamomum Maton) is a highly valuable commercial spice crop, originating from the Western Ghats of southern India. It has importance both as a spice and for its medicinal properties. An efficient and reliable micropropagation protocol using shoot tips as explants is presented which can be utilized for development of elite planting material. Growth patterns of cardamom shoots were analyzed on 45 media treatments and best shoot proliferation was recorded on Murashige and Skoog (MS) medium supplemented with 4.4 μM 6-benzylaminopurine (BAP) and 2.32 μM kinetin (Kn) with 5.83 shoots regenerated per explant. The longest shoots (6 cm) were observed on 0.44 μM BAP and 2.32 μM Kn containing medium. Regenerated shoots rooted well on full strength MS basal medium, generating 3.50 roots per explant with an average root length of 4.33 cm within 4 wk. Successful hardening with a field survival percentage of 80% was achieved after acclimatization of well-developed plantlets. Genetic stability of the micropropagated plants was confirmed using 13 ISSR markers. This study reports an improved micropropagation protocol for cardamom with an enhanced rate of shoot multiplication leading to the production of healthy shoots which can be easily rooted and successfully transferred to the field.

Efficient Micropropagation of Chestnut Hybrids (Castanea spp.) Using Modified Woody Plant Medium and Zeatin Riboside

The chestnuts genus (Castanea spp.) is comprised of economically important trees native to the Northern hemisphere that are used as food and hardwood timber. Here, a very efficient method for micropropagation of European × Japanese chestnut hybrids (Castanea sativa × C. crenata) is described. Woody Plant Medium was used as the basal medium. In vitro shoots of four rootstock cultivars were micropropagated without shoot-tip necrosis on multiplication medium containing 5.7 or 11.4 µmol·L−1 zeatin riboside, and were rooted on rooting medium containing 2.46 µmol·L−1 indolebutyric acid. Monthly shoot multiplication rates for each cultivar were 2–5 folds. In vitro rooting percentages for four cultivars were 87% for ‘Maraval’, 67% for ‘Marigoule’, 93% for ‘Marsol’, and 97% for ‘Précoce Migoule’. Within a 5 week period, 80%–95% of rooted shoots were successfully acclimated under high humidity conditions after they were planted in either soil or rockwool.

Micropropagation and in vitro conservation of Alcantarea nahoumii (Bromeliaceae), an endemic and endangered species of the Brazilian Atlantic Forest

Alcantarea nahoumii (Leme) J. R. Grant is a species native to the Atlantic Forest that stands out for ornamental purposes. The objective of this work was to evaluate the in vitro germination of A. nahoumii seeds and establish a micropropagation protocol for production of seedlings so as to minimize the effects of predatory extractivism and develop an in vitro conservation system. Mature seeds were disinfested, established in three culture media (MS, MS½ and MS⅓) and incubated at four temperatures (20, 25, 30 and 35ºC) in a germination chamber. In the micropropagation experiment, stem segments were introduced in MS medium supplemented with 0.5 μM of 1-naphthaleneacetic acid (NAA) and 0.0, 2.2, 4.4 and 6.6 μM of 6-benzylaminopurine (BAP). For the in vitro conservation, plantlets were established in MS or MS½ medium supplemented with 15 g L-1 or 30 g L-1 of sucrose. The plants were acclimated with commercial substrate. The highest seed germination percentages were promoted by temperature conditions of 20 and 25ºC, with MS culture medium. The highest multiplication rate of shoots was obtained from the treatment without addition of the growth regulator or when combined with 2.2 μM of BAP + 0.5 μM of NAA. The acclimation of the plants occurred with high survival rate. The species can be conserved in vitro under slow growth condition for 24 months when incubated in MS medium supplemented with 30 g L-1 of sucrose.

Ameliorated reserpine production via in vitro direct and indirect regeneration system in Rauvolfia serpentina (L.) Benth. ex Kurz.

Rauvolfia serpentina (L.) Benth. ex Kurz., popularly known as Indian Snakeroot plant, belonging to Apocynaceae family, holds immense medicinal importance, owing to its rich source of multiple secondary metabolites such as ajmaline, ajmalicine, reserpine, and serpentine. To meet the constant demands for the key secondary metabolite (reserpine) by majority of the pharmaceutical industries, the present study assessed the effects of direct and indirect regeneration system on amelioration of reserpine accumulation in shoots of R. serpentina. In vitro multiple shoot cultures were established using shoot tip explants. Best results for shoot initiation, multiplication, and biomass production were obtained in case of Murashige and Skoog medium, supplemented with 1 mg/l N6-benzyladenine. The multiple shoots were then sub-cultured on cytokinin–auxin combination media for further proliferation. Highest shoot and leaf multiplication rates and the most enhanced biomass were obtained in case of 1–1.5 mg/l Kinetin + 0.2 mg/l α-naphthalene acetic acid (NAA). Callus induction and its subsequent proliferation was obtained using 1.5 mg/l 2,4-dichlorophenoxyacetic acid. The best indirect shoot regeneration with highest shoot and leaf proliferation from calli was observed in case of 1 mg/l thidiazuron + 0.2 mg/l NAA. Reserpine content estimation via HPTLC from in vitro shoots (direct regeneration) and calli (indirect regeneration) were recorded to undergo an almost three-fold and two-fold increment (respectively) in comparison to that of the mother plant. Thus, in vitro direct regeneration system proved to be more effective and efficient in ameliorating the reserpine content.

Polynomial regressions reveal that levels of chlorophyll a, carotenoids, soluble phenolics and aldehydes modify mathematically sugarcane shoot multiplication rate in temporary immersion bioreactors under salt stress

Polynomial regression analysis is a powerful statistical tool used to describe non-linear relationships. The goodness-of-fit of this model is assessed by evaluating the coefficient of determination (R2). An R2 value closer to 1 is indicative of a strong correlation between the two under consideration. While polynomial regression analysis has been widely used in studies of plant stress responses to stress, to the best of our knowledge, this represents the first report on the application of this method to study the response of sugarcane plants to salt stress in Temporary Immersion Bioreactors (TIBs). In this context, sugarcane plants were exposed to salt stress while undergoing multiplication in TIBs. At the end of the multiplication cycle, the levels of biochemical metabolites (i.e. chlorophylls, carotenoids, phenolics and aldehydes) were evaluated. Polynomial regression analysis was subsequently used to elucidate the relationships between shoots multiplied under high salt stress conditions and consequent metabolite levels. The results indicated that the levels of chlorophyll a had a strong positive relationship (in mathematical terms) with shoot multiplication rate (R2 = 0.7063) with a corresponding high determination coefficient. In contrast, shoot multiplication rate was decreased in response to increased levels of carotenoids, soluble phenolics in shoots, and other aldehydes. Changes in levels of chlorophyll b, cell wall-linked phenolics, soluble phenolics excreted to the culture medium and malondialdehyde did not seem to (mathematically) influence sugarcane shoot multiplication in TIBs under salinity stress. The results from the present investigation provides evidence for the application of polynomial regression analysis as a tool to elucidate relationships between plant metabolites as markers for stress and shoot multiplication (as an indicator of growth) in in vitro systems. It is recommended that this statistical tool would be useful in an overall in vitro screening approach to investigate the stress response of other plant species in similar systems.

In vitro propagation of Camellia fascicularis: a plant species with extremely small populations

Camellia fascicularis is an endangered evergreen ornamental plant with pale yellow flowers. An efficient and reproducible in vitro regeneration method is required for its large-scale propagation and germplasm conservation. In this study, one axillary bud per nodal stem was obtained from C. fascicularis cultured on Murashige &amp; Skoog (MS) medium containing 0.1 mg L−1 indole-3-acetic acid (IAA) combined with 1.0 mg L−1 6-benzylaminopurine (BA). Axillary buds from the stem segments were transferred to modified woody plant medium (WPM) supplemented with 3.0 mg L−1 BA in combination with 0.3 mg L−1 IAA for multiplication, thereby resulting in a high shoot multiplication rate of 6.8. Multiple shoots were divided into nodal stems and shoot tips and were induced to root. The shoot tips were induced to root by culturing on one-half MS medium supplemented with 2.0 mg L−1 indole-3-butyric acid (IBA) in combination with 0.3 mg L−1 α-naphthalene acetic acid (NAA), which resulted in 76.0% rooting efficiency with 2.3 roots per shoot. The optimal hormone ratio for inducing rooting of nodal stems was 1.0 mg L−1 IBA in combination with 2.0 mg L−1 NAA, which resulted in 72.7% rooting efficiency with 1.7 roots per nodal stem. These two rooted plantlets were successfully acclimatized and established in a greenhouse.

Optimizing axillary shoot culture as a short-term conservation method for American chestnut (Castanea dentata)

Protocols were investigated in the short-term conservation of Castanea dentata (Marsh.) Borkh. to maximize axillary shoot multiplication rates at the genotype level and to reduce the incidence of shoot tip necrosis (STN). Factors investigated included explant growth stage (embryo, seedling, and mature stages) of the source material and two culture incubation temperatures (21 ± 1 °C and 31 ± 1 °C). Multiplication rate was measured across 22 genotypes. The role of 6-benzylaminopurine (0.5, 1.0, 2.0, and 4.0 μmol·L–1), calcium (3.0 and 6.0 mmol·L–1), boron (0.025 mmol·L–1), magnesium (3.0 mmol·L–1), and gelling agent (agar, 6.0, 7.0, and 8.0 g·L–1; gellan gum, 3.0, 3.5, and 4.0 g·L–1) on STN was investigated. Genotypes derived from 4-month-old seedlings had the greatest overall multiplication rate (7.87 ± 0.38 at 6 weeks). Temperature affected multiplication rate in three of eight genotypes tested, with multiplication rate greater at 21 ± 1 °C for one genotype and greater at 31 ± 1 °C for two genotypes. Multiplication rates differed significantly between genotypes and ranged from 1.45× at 12 weeks to 13.25× at 6 weeks. Incidence of STN was decreased to 1.40% ± 0.02% at 4.0 μmol·L–16-benzylaminopurine. The development of an efficient axillary shoot culture system for C. dentata greatly benefits current conservation efforts.

Modifying sugarcane mineral levels through sodium chloride and mannitol exposure in temporary immersion bioreactors

Temporary immersion bioreactors (TIBs) have been shown to be useful for studying plant stress physiology and inducing chemical mutagenesis. This study describes the effects of exposure to NaCl (salt stress) and mannitol (osmotic stress) within TIB on sugarcane mineral levels in vitro. Shoots were exposed to concentration of NaCl (89.4 mM) and mannitol (123.1 mM) previously shown to result in a 50% reduction in multiplication rate for 30 d. Thereafter, shoot multiplication rate, shoot cluster fresh weight, and levels of selected minerals were measured. Using ICP-OES, the following minerals were quantified: Na, Ga, Mn, Cr, K, Zn, Ca, Li, Mg, Sr, Co, B, Fe, S, P, Al, Ba, and N. Both NaCl and mannitol decreased shoot multiplication by c. 53% and except for Al and Ba altered mineral levels significantly relative to the control: Na accumulation increased markedly (six-fold in NaCl treatment); levels of Ga, Mn, Cr, K, and Zn changed moderately; Ca, Li, Mg, Sr, Co, B, Fe, S, P, and N levels changed to a limited extent. In terms of the minerals that were most affected, Ga, Mn, K, and Zn levels declined under both stresses; Cr appears to be the only exception, having decreased under the salinity stress and increased under the osmotic stress. Our results suggest that both stresses not only affect growth in the same manner and degree but also appear to have similar effects on the physiological mechanisms that modulate mineral levels at the cellular level under stress conditions. Sugarcane growth inhibition appeared to be mainly due to turgor loss under mannitol-induced stress and the accumulation of Na ions under salt stress. Stress resistance in this species is most likely promoted by the retention of a “safe” water status, a high amount of K and Ca, and a low level of Na.

An efficient micropropagation protocol for an endangered ornamental tree species (Magnolia sirindhorniae Noot. & Chalermglin) and assessment of genetic uniformity through DNA markers

Magnolia sirindhorniae Noot. & Chalermglin is an endangered species with high ornamental and commercial value that needs to be urgently protected and judiciously commercialized. In this study, a protocol for efficient regeneration of this species is standardized. The lateral buds of the M. sirindhorniae plant were used as an explant. Half-strength Murashige and Skoog (MS) medium supplemented with 2.0 mg/L 6-benzyladenine (BA), 0.1 mg/L α-naphthaleneacetic acid (NAA), and 2.0 mg/L gibberellic acid (GA3) was found to be the optimal medium for shoot induction. The maximum shoot multiplication rate (310%) was obtained on Douglas-fir cotyledon revised medium (DCR) fortified with 0.2 mg/L BA, 0.01 mg/L NAA, and additives. The half-strength DCR medium supplemented with 0.5 mg/L NAA and 0.5 mg/L indole-3-butyric acid (IBA) supported the maximum rate (85.0%) of in vitro root induction. After a simple acclimatization process, the survival rate of plantlets in a substrate mixture of sterile perlite and peat soil (1:3; v/v) was 90.2%. DNA markers were used for assessment of genetic uniformity, confirming the genetic uniformity and stability of regenerated plants of M. sirindhorniae. Thus, the described protocol can safely be applied for large scale propagation of this imperative plant.

A novel cost-effective medium for in vitro cultivation of Gentiana kurroo Royle using sugarcane bagasse

Objective: To develop a simple, cost effective and efficient medium by using sugarcane bagasse as a base material to replace the conventional Murashige and Skoog medium. Materials and Methods: Water extracts of sugarcane bagasse alongwith some macronutrients and plant growth regulators were gelled with 0.7% agar-agar powder. Nodal segments of G. kurroo were used as explants and inoculated in the medium and placed in growth chamber under standard conditions of light and temperature. Out of the tested combinations of plant growth regulators, 0.5 mg/l each of KN and BAP showed the excellent shoot multiplication and proliferation rate on the bagasse medium with the same potential as on the MS medium with an average of 5 or - 6 shoots / explant. In vitro rooting was obtained on half strength MS medium supplemented with IBA (0.5 mg/l) with an average length of 7-8 cm and 20-25 roots/ explant. The plants were hardened in a mixture of clay loam and farmyard manure (FYM) in 1:1(w/w) with 70-80% survival rate without any phenotypic abberations. Conclusion: The results from the present investigation indicate that sugarcane bagasse can be used as a cost effective substitute of MS medium for in vitro propagation of G.kurroo.