Standardization of zygotic embryo culture from Nerium oleander L. and comparative analysis of biosynthesized cardiac glycosides within in vitro and acclimatized plants

The primary result of our experiment revealed that the germination percentage of N. oleander mature seeds is only 30%. From this observation, the concept of protocol standardization for zygotic embryo culture of this plant was originated. Zygotic embryo culture was proved an efficient in vitro multiplication system of N. oleander. The maximum germination percentage (96%) of zygotic embryos was observed on ¼ MS medium with 15 gm/L sucrose, whereas the best growth medium was optimized as ½ B5 with same sucrose concentration. The second part of this study was aimed to find out the cardiac glycoside accumulation pattern in both in vitro and acclimatized plants. For this purpose, one-month-old in vitro plantlets and acclimatized plants were subjected to LC-MS analysis and 09 cardiac glycosides were detected and quantified in both the systems. Most of the cardiac glycosides including odoroside A (32.71 mg/gm DW), odoroside H (4.69 mg/gm DW) and oleandrin (0.52 mg/gm DW) were found to be accumulated at maximum level within in vitro plantlets. CG 840b (1.89 mg/gm DW) is the only cardiac glycoside, which was maximally accumulated in acclimatized plants. From this study, it can be concluded that, zygotic embryo culture is a better choice for in vitro multiplication of N. oleander when compared to matured seeds and in vitro grown plantlets of this species favor cardiac glycosides biosynthesis in comparison to acclimatized plants. Therefore, all future research on the enrichment of cardiac glycosides from this plant may be conducted on zygotic embryos derived in vitro grown plantlets or cultures.

Micropropagation and assessment of somaclonal variation in Galanthus transcaucasicus in vitro plantlets

In vitro culture of twin-scaling explants of Galanthus transcaucasicus with different concentrations of plant growth regulators (PGRs) including 0.5, 1, 2, 3, 4, 6, 8, and 10 mg L-1 naphthaleneacetic acid (NAA) and 0.5, 1, 2, 3, and 4 mg L-1 benzyladenine (BA) was studied. After 18 weeks, the number of regenerated bulblets and intensity of callus was measured. Subsequently, bulblets were transferred to a medium with 0.5, 1, 2, 3, and 4 mg L-1 NAA and 0.5, 1, 2, 3, and 4 mg L-1 BA and, after 15 weeks, the bulblets length and diameter were measured. The highest intensity of callus was obtained on 4 mg L-1 NAA or 8 mg L-1 NAA with 1 mg L-1 BA. The highest number of regenerated bulblets was detected with 6 mg L-1 NAA and 2 mg L-1 BA. The highest diameter of bulblets occurred on four mgL-1 NAA (9.4 mm), while the lowest was observed on 0.5 mg L-1 BA (1.83 mm). The analysis of genetic variation using ISSR revealed that there was no somaclonal variation among the regenerated plants from BA and low level of NAA, but there was a significant somaclonal variation at high concentrations of NAA.

Development of the first axillary in vitro shoot multiplication protocol for coconut palms

The coconut palm or “tree of life” is one of nature’s most useful plants and the demand for its fruit is increasing. However, coconut production is threatened by ageing plantations, pests and diseases. Currently, the palm is exclusively propagated via seeds, limiting the amount of planting material. A novel micropropagation method is presented, based on axillary shoot formation. Apical meristems of in vitro coconut seedlings are cultured onto Y3 medium containing 1 µM TDZ. This induces the apical meristem to proliferate through axillary shoots in ~ 27% of the initiated explants. These axillary shoots are seen as white clumps of proliferating tissue and can be multiplied at a large scale or regenerated into rooted in vitro plantlets. This innovative micropropagation method will enable the production of disease-free, high quality in vitro plantlets, which will solve the worldwide scarcity of coconut planting material.

Novel Methodology for Delivering Putrescine into the Apple Explants Using Hormone Anchored Nanotube

Multi wall carbon nanotubes have been successfully exploited as growth regulator for manipulation of plant development. Also, nanoparticles are gradually involved in target delivery systems as the carrier of hormones. Polyamines and their derivations play crucial roles in plant growth and development. Take the mentioned subjects into consideration, putrescine anchored carbon nanotube which had been labeled with fluorescein was synthetized in this study. A set of physiological and morphological parameters were assessed in an attempt to examine the usage potential of de novo synthetized nanotube in terms of plant in-vitro culture. For this purpose, the nanotube was applied onto the in-vitro plantlets of Malus niedzwetzkyana in three concentrations (0, 50 and 100 mg/l). Localization of the nanotube in the plantlets was accomplished using fluorescence microscopy. Bio-imaging of tissues indicated the existence of nanotube in nearly all studied organs. Application of the nanotube at both concentrations (50 and 100 mg/l) increased the rate of leaf formation and speeding up the plastochron. Also, proliferation of the plantlets was enhanced using the nanotube. The levels of the photosynthetic pigments, including chlorophyll a, b and carotenoids increased following application of the nanotube. Glutathione peroxidase activity was significantly affected by the nanotube. However, polyphenol oxidase and peroxidase were not influenced by the nanotube. Stomatal density was increased by treatment of the plantlets with the nanotube. Representing geometrical transformation of shape as a thin plate spline revealed that the nanotube effectively increased longitudinally of stomata and changes their aspect ratio.

In vitro propagation of Nanorrhinum ramosissimum (Wall.) Betsche: A traditionally important medicinal plant

An efficient micropropagation protocol facilitates successful conservation and improvement of Nanorrhinum ramosissimum (Wall.) Betsche by biotechnological means. Shoot tip explants exhibited optimal organogenic response when inoculated on half-strength(1/2) Murashige and Skoog (MS) medium supplemented with kinetin (KN) and indole-3-acetic acid (IAA) (0.5 mg/L each). Shoot organogenesis was further enhanced when the multiplication medium was fortified with dextrose (1%) (2.6 shoots/explant; 7.9 cm shoot length). The regenerated shoots formed roots; however, the best rooting frequency (87%) was achieved on half-strength MS medium containing only IAA (0.5 mg/L). Four-week-old in vitro plantlets were acclimatized with 95% survival under greenhouse conditions. The regeneration protocol developed in this study can be utilized for germplasm conservation of this elite traditional medicinal plant.

Mass Propagation of Nauclea diderrichii (de Willd. & Th. Dur) Merr. Seedlings through Tissue Culture Technique

Nauclea diderrichii is a tree species of economic importance. However, its plantation establishment is limited by inadequate seedling production. Hence, there is ample scope of tissue culture for its mass propagation. Its in vitro plantlets development as affected by media strengths indicated that 100 % seed germination was obtained in full MS basal medium while the least (3.35 %) was from quarter-strength at 8 Weeks after inoculation (WAI). The effects of BAP and NAA assessed on the growth of its sub-cultured plantlets showed that highest number of leaves (17) and adventitious shoots (3) were obtained from MS basal medium supplemented with 0.1 mg/l BAP only. Whereas, highest shoot length (3.61 cm) and average number of roots (5/plantlet) were obtained from the same medium without hormone(s) at 8 WAI. Further sub-culturing into MS with 0.05 mg/l NAA resulted into plantlets having optimum shoot and massive root growth ready for acclimatization in 6 WAI. The plantlets were successfully acclimatized using coconuthusk/ topsoil mixture with 90 % survival. Plant Tissue Cult. & Biotech. 31(1): 51-60, 2021 (June)

Shoot Multiplication and Callus Induction of Labisia pumila var. alata as Influenced by Different Plant Growth Regulators Treatments and Its Polyphenolic Activities Compared with the Wild Plant

This study aims to investigate whether the in vitro-cultured L. pumila var. alata has higher antioxidant activity than its wild plant. An 8-week-old L. pumila var. alata nodal segment and leaf explants were cultured onto Murashige and Skoog (MS) medium supplemented with various cytokinins (zeatin, kinetin, and 6-benzylaminopurine (BAP)) for shoot multiplication and auxins (2,4-dichlorophenoxyacetic acid (2,4-D) and picloram) for callus induction, respectively. The results showed that 2 mg/L zeatin produced the optimal results for shoot and leaf development, and 0.5 mg/L 2,4-D produced the highest callus induction results (60%). After this, 0.5 mg/L 2,4-D was combined with 0.25 mg/L cytokinins and supplemented to the MS medium. The optimal results for callus induction (100%) with yellowish to greenish and compact texture were obtained using 0.5 mg/L 2,4-D combined with 0.25 mg/L zeatin. Leaves obtained from in vitro plantlets and wild plants as well as callus were extracted and analyzed for their antioxidant activities (DPPH and FRAP methods) and polyphenolic properties (total flavonoid and total phenolic content). When compared with leaf extracts of in vitro plantlets and wild plants of L. pumila var. alata, the callus extract displayed significantly higher antioxidant activities and total phenolic and flavonoid content. Hence, callus culture potentially can be adapted for antioxidant and polyphenolic production to satisfy pharmaceutical and nutraceutical needs while conserving wild L. pumila var. alata.

Expression Level of Mature miR172 in Wild Type and StSUT4-Silenced Plants of Solanum tuberosum Is Sucrose-Dependent

In potato plants, the phloem-mobile miR172 is involved in the sugar-dependent transmission of flower and tuber inducing signal transduction pathways and a clear link between solute transport and the induction of flowering and tuberization was demonstrated. The sucrose transporter StSUT4 seems to play an important role in the photoperiod-dependent triggering of both developmental processes, flowering and tuberization, and the phenotype of StSUT4-inhibited potato plants is reminiscent to miR172 overexpressing plants. The first aim of this study was the determination of the level of miR172 in sink and source leaves of StSUT4-silenced as well as StSUT4-overexpressing plants in comparison to Solanum tuberosum ssp. Andigena wild type plants. The second aim was to investigate the effect of sugars on the level of miRNA172 in whole cut leaves, as well as in whole in vitro plantlets that were supplemented with exogenous sugars. Experiments clearly show a sucrose-dependent induction of the level of mature miR172 in short time as well as long time experiments. A sucrose-dependent accumulation of miR172 was also measured in mature leaves of StSUT4-silenced plants where sucrose export is delayed and sucrose accumulates at the end of the light period.