Natural biosynthesis, pharmacological applications, and sustainable biotechnological production of ornamental plant-derived anthocyanin: beyond colorants and aesthetics.

Flowers have long been admired for their aesthetic qualities and have even found their way to be included in the human diet. Among the many chemical compounds found in flowers, anthocyanins stand out for their versatile applications in the food, cosmetic, and nutraceutical industries. The biosynthetic pathway of anthocyanins has been thoroughly studied in certain flower species, leading to the detection of key regulatory genes that can be controlled to enhance the production of anthocyanins via biotechnological methods. Nevertheless, the quantity and form of anthocyanins found in natural sources differ, both qualitatively and quantitatively, depending on the ornamental plant species. For this reason, research on in vitro plant cultures has been conducted for years in an attempt to comprehend how these essential substances are produced. Different biotechnological systems, like in vitro plant cell, organ, and tissue cultures, and transgenic approaches, have been employed to produce anthocyanins under controlled conditions. However, multiple factors influence the production of anthocyanins and create challenges during large-scale production. Metabolic engineering techniques have also been utilized for anthocyanin production in microorganisms and recombinant plants. Although these techniques are primarily tested at lab- and pilot-scale, limited studies have focused on scaling up the production. This review analyses the chemistry and biosynthesis of anthocyanin along with the factors that influence the biosynthetic pathway. Further emphasis has been given on strategies for conventional and non-conventional anthocyanin production along with their quantification, addressing the prevailing challenges, and exploring ways to ameliorate the production using the in vitro plant cell and tissue culture systems and metabolic engineering to open up new possibilities for the cosmetic, pharmaceutical, and food industries.

Morpho-histology of co-occurrence of somatic embryos, shoots, and inflorescences within a callus of Limonium 'Misty Blue'.

This is the first attempt to report the co-occurrence of somatic embryos, shoots, and inflorescences and their sequential development from stem cell niches of an individual callus mass through morpho-histological study of any angiosperm. In the presence of a proper auxin/cytokinin combination, precambial stem cells from the middle layer of a compact callus, which was derived from the thin cell layer of the inflorescence rachis of Limonium, expressed the highest level of totipotency and pluripotency and simultaneously developed somatic embryos, shoots, and inflorescences. This study also proposed the concept of programmed cell death during bipolar somatic embryo and unipolar shoot bud pattern formation. The unique feature of this research was the stepwise histological description of in vitro racemose inflorescence development. Remarkably, during the initiation of inflorescence development, either a unipolar structure with open vascular elements or an independent bipolar structure with closed vascular elements were observed. The protocol predicted the production of 6.6 ± 0.24 and 7.4 ± 0.24 somatic embryos and shoots, respectively, from 400 mg of callus, which again multiplied, rooted, and acclimatised. The plants' ploidy level and genetic fidelity were assessed randomly before acclimatisation by flow cytometry and inter simple sequence repeats (ISSR) marker analysis. Finally, the survivability and flower quality of the regenerated plants were evaluated in the field.

Developments in biotechnological tools and techniques for production of reserpine.

In the quest for novel medications, researchers have kept on studying nature to unearth beneficial plant species with medicinal qualities that may cure various diseases and disorders. These medicinal plants produce different bioactive secondary metabolites with immense therapeutic importance. One such valuable secondary metabolite, reserpine (C33H40N2O9), has been used for centuries to cure various ailments like hypertension, cardiovascular diseases, neurological diseases, breast cancer, and human promyelocytic leukaemia. Rauvolfia spp. (family Apocynaceae) is an essential reservoir of this reserpine. The current review thoroughly covers different non-conventional or in vitro-mediated biotechnological methods adopted for pilot-scale as well as large-scale production of reserpine from Rauvolfia spp., including techniques like multiple shoot culture, callus culture, cell suspension culture, precursor feeding, elicitation, synthetic seed production, scale-up via bioreactor, and hairy root culture. This review further analyses the unexplored and cutting-edge biotechnological tools and techniques to alleviate reserpine production. KEY POINTS: • Reserpine, a vital indole alkaloid from Rauvolfia spp., has been used for centuries to cure several ailments. • Overview of biosynthetic pathways and biotechnological applications for enhanced production of reserpine. • Probes the research gaps and proposes novel alternative techniques to meet the pharmaceutical industry's need for reserpine while reducing the over-exploitation of natural resources.

Colchicine-mediated in vitro polyploidization in gerbera hybrid.

An efficient in vitro protocol for high-frequency polyploidization for the first time in gerbera hybrid (BGC-2019-01) was developed in the present study. Two-week-old in vitro-developed shoots (tips) were treated individually with 0.1%, 0.25% and 0.5% (w/v) colchicine solutions for 4, 6, 8, and 12 h. The colchicine-treated shoot tips were then inoculated on Murashige and Skoog (MS) medium fortified with 1.5 mg/l meta-Topolin for multiple shoot proliferation and later transferred into 1.5 mg/l indole-3-acetic acid-fortified MS medium for rooting of shoots. The ploidy levels of the colchicine-treated and regenerated plantlets along with the non-treated ones were confirmed via flow cytometry analysis and metaphasic chromosome count. The highest frequency of tetraploid plantlets (50%) were obtained when shoot tips were treated with 0.1% colchicine for 4 h. Morphological observations revealed that induced tetraploid plantlets exhibited delayed fresh shoot initiation, fewer but longer shoots, as well as fewer but broader leaves. Likewise, the study of stomata revealed that in comparison to their diploid counterparts, the tetraploid plantlets exhibited less frequent yet significantly larger stomata, and higher number of chloroplasts. The tetraploids were recorded with significantly higher chlorophyll, carotenoid, and anthocyanin content during the photosynthetic pigment analyses. During ex vitro acclimatization and field growth, the tetraploid plants exhibited delayed proliferation but with higher vigor and thickened broad leaves. The genetic uniformity among the diploid and the tetraploid plants was confirmed using conserved DNA-derived polymorphism (CDDP), directed amplification of minisatellite-region DNA (DAMD), inter simple sequence repeats (ISSR), and start codon targeted (SCoT) polymorphism marker systems. The tetraploids developed in the present study would be of immense importance for the genetic improvement of gerbera as far as its ornamental values are concerned.

Advancements and prospectives of sugar beet (Beta vulgaris L.) biotechnology.

Sugar beet (Beta vulgaris L.) is the second largest sugar-producing crop (following sugarcane), accounting around 40% of total global sugar output. It has been reckoned with huge contribution in sugar, ethanol, and fodder industries. Since sugar beet is recalcitrant in nature, to address the multifaceted difficulties associated with its conventional propagation, several biotechnological tools and techniques aiming with in vitro-based mass regeneration-cum-genetic enhancement are becoming popular. The implementation of effective methodology for in vitro regeneration from ex vitro explant sources becomes the necessity for successful commercial-scale clonal propagation and genetic modification. Substantial research achievements have been made in the past few decades in connection to the optimization of in vitro protocols for direct and callus-mediated regeneration, homozygous line production, somatic hybridization, and genetic transformation of sugar beet. The current review summarizes several reported findings on various physio-chemical factors responsible for direct, indirect organogenesis, somatic embryogenesis, protoplast culture, haploid culture, acclimatization accountable for plantlet mass multiplication, assessing the genetic integrity of in vitro-cultured plantlets, and, finally, successful transgenic approaches to remediate biotic and abiotic stresses. Furthermore, this study highlights undiscovered regions, research gaps, and major bottlenecks that might be considered in developing significant innovative ideas related to sugar beet biotechnology in the near future. KEY POINTS: • Sugar beet, the second largest sugar producer, is a major contributor in sugar, ethanol, and fodder industries. • Current review comprehensively evaluates diverse factors influencing the success of in vitro biotechnological interventions. • This review further highlights the research gaps and offers way outs to attain comprehensive genetic improvement.

Biotechnology of banana (Musa spp.): multi-dimensional progress and prospect of in vitro-mediated system.

Banana (Musa spp.), commonly known as 'Adam fig' and 'Fruit of wise man', is a commercial herbaceous tropical fruit, which governs its antiquity from ancient periods in the Indian and African subcontinent. All parts of the plant, i.e. stem, leaf, root, inflorescence, peel, fruit, and flower, have significant medicinal and nutritional values. Owing to its multitude of uses, it is known as 'Kalpavriksha' (plant of virtues). To combat multi-faceted issues related to traditional propagation, in vitro-based regeneration-cum-genetic improvement approaches become the trend of the hour. The present review illustrates various physico-chemical factors that are responsible for successful in vitro regeneration and acclimatization, protoplast culture, anther and microspore culture, cryopreservation and synthetic seed production, genetic transformation, mutagenesis, and nanotechnological and omics approaches. The key intent of this article is to present an insight on in vitro biotechnological research advances in the past decade, to identify the research gaps, unexplored areas, and major shortcomings associated with banana biotechnology and to highlight the potential approaches to mitigate them. Eventually, this review made salient conclusions and recommendations paving the way forward for the banana researchers to develop innovative ideas in order to enhance the propagation frequency and to ensure the genetic improvement of banana. KEY POINTS: • This review addresses biotechnological interventions in Banana (Musa spp.) for enhanced propagation and quality improvement. • Highlights factors influencing in vitro regeneration, conservation, and genetic transformation. • Provides novel ideas to harness the qualitative and quantitative genetic improvement.

Drought tolerance improvement in Solanum lycopersicum: an insight into "OMICS" approaches and genome editing.

Solanum lycopersicum (tomato) is an internationally acclaimed vegetable crop that is grown worldwide. However, drought stress is one of the most critical challenges for tomato production, and it is a crucial task for agricultural biotechnology to produce drought-resistant cultivars. Although breeders have done a lot of work on the tomato to boost quality and quantity of production and enhance resistance to biotic and abiotic stresses, conventional tomato breeding approaches have been limited to improving drought tolerance because of the intricacy of drought traits. Many efforts have been made to better understand the mechanisms involved in adaptation and tolerance to drought stress in tomatoes throughout the years. "Omics" techniques, such as genomics, transcriptomics, proteomics, and metabolomics in combination with modern sequencing technologies, have tremendously aided the discovery of drought-responsive genes. In addition, the availability of biotechnological tools, such as plant transformation and the recently developed genome editing system for tomatoes, has opened up wider opportunities for validating the function of drought-responsive genes and the generation of drought-tolerant varieties. This review highlighted the recent progresses for tomatoes improvement against drought stress through "omics" and "multi-omics" technologies including genetic engineering. We have also discussed the roles of non-coding RNAs and genome editing techniques for drought stress tolerance improvement in tomatoes.

Agri-biotechnology of coriander (Coriandrum sativum L.): an inclusive appraisal.

Bountiful expression of bioactivity of phytochemicals obtained from spice crops like coriander gifts them the label of being natural antioxidants. It is well-accepted and time-tested towards contributing to human wellbeing. The accomplishment of coriander production is fundamentally influenced by genetic, agroclimatic, and agronomic factors. Despite the fact that there are very restricted options to manage the first two factors, the third one is apparently imperative to arbitrate as far as the elevated yield and enhanced quality are concerned. On the other hand, an indomitable, object-oriented, controlled agrotechnological and biotechnological intervention can also contribute towards better yield and quality of coriander. There are several accounts of the successful use of such technologies in order to genetically improve the qualitative and quantitative indicators of coriander. However, often these areas are not comprehensively explored and utilized. In that context, the present review highlights the botanical features, origin and distribution, multi-dimensional importance, pre- and post-harvest crop management, phytochemical production, and germplasm conservation, including the in vitro-based regeneration methods along with molecular marker-based biotechnological and omics approaches attempted in coriander until date. In addition, the possibility of the yet-to-be-explored agri-biotechnological methods and their potential for genetic improvement of this crop has also been reviewed in this appraisal. KEY POINTS: • Coriander, used both as an herb and spice, is popular in the pharmaceutical and culinary industries. • The current review provides insight into agrotechnological and biotechnological interventions for better yield and quality. • Provides novel ideas to harness the comprehensive qualitative and quantitative genetic improvement based on the potential use of promising biotechnological tools and techniques.

Picloram-induced enhanced callus-mediated regeneration, acclimatization, and genetic clonality assessment of gerbera.

BACKGROUND: Gerbera jamesonii Bolus ex Hooker f. (African daisy) is listed among the top five most important ornamental plants in the global floricultural industry. To satisfy its demand, the floriculture industry relies on reproducible and effective propagation protocol while retaining the genetic uniformity of G. jamesonii. The present study, for the first time, reports the potential of picloram for enhanced induction of organogenic calli from leaves of G. jamesonii and its high-frequency indirect regeneration. RESULTS: The fastest induction of calli with maximum fresh and dry weight was recorded in the Murashige and Skoog (MS) semisolid medium supplemented with 1 mg/l picloram. In addition, callus induction was observed in 2,4-dichlorophenoxy acetic acid- and α-napthaleneaceticacid-supplemented media but with delayed response and reduced fresh and dry weight. The proliferated calli were transferred to shoot induction media containing MS salt and 0.5-1 mg/l N6-benzylaminopurine, kinetin, or thidiazuron. A mean number of ~6 shoots per callus were developed after 5 days of culture in the MS medium supplemented with 1 mg/l kinetin, with a mean length of 5.2 cm. Successful rooting of shoots was achieved in the MS medium fortified with 1.5 mg/l indole-3-acetic acid, wherein the earliest root initiation (~5 days), as well as the maximum number (~9) and length (~4.8 cm) of roots, were recorded. Complete plantlets were primarily acclimatized in sand before being transferred to a mixed substrate (of soil, sand, tea leaf waste, and cow urine) that secured >90% survival and further growth of the plantlets. Eventually, clonal fidelity of the in vitro regenerants assessed via inter-simple sequence repeats (ISSR) primers exhibited a monomorphic banding patterns that suggested genetic integrity within the plantlets as well as with their mother plant. CONCLUSIONS: The results of the present study should be of interest for commercial propagation and mutagenesis- as well as genetic transformation-related research.

Tissue culture-based genetic improvement of fava bean (Vicia faba L.): analysis on previous achievements and future perspectives.

Fava bean is an extremely important legume and serves immense potential to function as an ingredient as pulse proteins in human diet. Bearing the proficiency of yielding magnanimous amount of functional and nutritional ingredients, this bean deserves to replace any other leguminous crop too. The instability of fava bean in its yield makes breeding for crop improvement difficult, and its high susceptibility to a number of abiotic and biotic stresses additionally results in unstable yields. The self-incompatibility leads to the formation of a limited genetic pool and shows a slow progress in breeding. The plant is highly recalcitrant, making it an onerous task to micropropagate or regenerate fava beans under in vitro conditions. Another fly in the ointment is the release of phenolic compounds by the plant. There are several endeavours that have been made to establish in vitro regeneration, protoplast culture, and genetic transformation and to genetically improve this plant. Nonetheless there are a number of promising cutting-edge technologies that are yet to be harnessed in order to ensure its comprehensive and sustainable genetic improvement. The in vitro-based technologies of this legume and its untraveled path in the plant tissue culture-mediated approaches can assist further genetic manipulation of this plant species in a smoother manner and at an exponential rate. Creation of a single review comprising all the updates and genetic advancements in fava bean is an absolute necessity of the hour. Thus, the importance of this review remains at the peak as it covers a vast range of information, starting from the basic description to the utmost modern stages of advancement in the selected crop. Overall interpretation of the review is aimed at encouraging readers to focus on almost all possible dimensions of international research, already executed, and is being executed in fava bean, thereby helping to understand the demand and advantages of the crop, even at the molecular level.Key points• Fava bean, commonly known as "poor man's meat", is a protein-rich legume with multiple nutritional and pharmacological benefits.• Its highly recalcitrant response makes in vitro interventions quite challenging for its genetic improvement.• This review delves into biotechnological interventions for its advancements to date and highlights major hurdles and potential research solutions to ensure comprehensive genetic improvement.

Induced autopolyploidy-a promising approach for enhanced biosynthesis of plant secondary metabolites: an insight.

BACKGROUND: Induced polyploidy serves as an efficient approach in extricating genetic potential of cells. During polyploidization, multiple sets of chromosomes are derived from the same organism resulting in the development of an autopolyploid. Alterations owing to artificially induced polyploidy level significantly influence internal homeostatic condition of resultant cells. MAIN TEXT: Induced autopolyploidy transpires as a result of an increase in the size of genome without any change in elementary genetic material. Such autopolyploidy, artificially induced via application of antimitotic agents, brings about a lot of beneficial changes in plants, coupled with very few detrimental effects. Induced autopolyploids exhibit superior adaptability, endurance to biotic and abiotic stresses, longer reproductive period and enzyme diversity coupled with enhanced rate of photosynthesis and gene action in comparison to their diploid counterparts. However, reduced rate of transpiration and growth, delay in flowering are some of the demerits of autopolyploids. Inspite of these slight unfavourable outcomes, induced autopolyploidization has been utilized in an array of instances wherein genetic improvement of plant species is concerned, since this technique usually boosts the biomass of concerned economic parts of a plant. In other way, it is also evident that multiplication of genome bestows enhanced production of secondary metabolites, which has contributed to a significant commercial value addition especially for plants with medicinal importance, in particular. CONCLUSION: This review makes an attempt to explore the system and success of antimitotic agents vis-à-vis artificial autopolyploidization, interfered with the biosynthesis-cum-production of secondary metabolites having cutting-edge pharmaceutical importance.

Advances in biotechnology of Emblica officinalis Gaertn. syn. Phyllanthus emblica L.: a nutraceuticals-rich fruit tree with multifaceted ethnomedicinal uses.

Emblica officinalis Gaertn. syn. Phyllanthus emblica L., universally known as 'Amla' or 'Aonla' or 'Indian gooseberry', is a popular fruit tree belonging to the family Euphorbiaceae and order Geraniales. It is said to be the very first tree that originated on earth, as claimed by age-old Indian mythology. Almost all parts of the tree i.e., root, bark, leaf, flower, fruit and seed are utilized in Ayurvedic and Unani medicinal formulations to improve the overall digestive process, decrease fever, act as a blood purifier, relieve asthma and cough, improve heart health, etc. This tree contains major secondary metabolites like emblicanin-A and emblicanin-B, and also is an affluent source of vitamin-C. Additionally, some other secondary metabolites like tannins, gallic acid, pyrogallol, and pectin are also present in significant amounts. Conventional propagation has been improved via suitable interventions of agrotechnology both in production and protection areas. However, the rate of propagation remains slower; therefore, attempts have been made for biotechnological advancements on E. officinalis. The present review makes an attempt to highlight the botanical description, geographical distribution, ethnopharmacological importance, conventional propagation and protection of this medicinal tree, describing the in vitro-based plant organ and tissue culture methods like direct and indirect organogenesis and somatic embryogenesis along with interventions of molecular marker-based biotechnology and nanotechnology. Further, the prospect of the yet-to-be-explored biotechnological methods for secondary metabolite enhancement like cell suspension, protoplast culture, genetic transformation, etc. and their potential for enhanced emblicanin production have also been discussed in this appraisal.

Hairy root culture technology: applications, constraints and prospect.

Hairy root (HR) culture, a successful biotechnology combining in vitro tissue culture with recombinant DNA machinery, is intended for the genetic improvement of plants. This technology has been put to use since the last three decades for genetic advancement of medicinal and aromatic plants and also to harvest the economical products in the form of secondary metabolites that are significantly important for their ethnobotanical and pharmacological properties. It also provides an efficient way out for the quicker extraction and quantification of the valuable phytochemicals. The current review provides an account of the in vitro HR culture technology and its wide-scale applications in the field of research as well as in pharmaceutical industries. Different facets of HR with respect to the culture establishment, phytochemical production as well as research investigations concerning the areas of gene manipulation, biotransformation of the secondary metabolites, phytoremediation, their industrial utilisations and different problems encountered during the application of this technology have been covered in this appraisal. Eventually, an idea has been provided on HR about the recent trends on the progress of this technology that may open up newer prospects in near future and calls for further research and explorations in this field. KEY POINTS: • Genetic engineering-based HR culture aims towards enhanced secondary metabolite production. • This review explores an insight in the HR technology and its multi-faceted approaches. • Up-to-date ground-breaking research applications and constraints of HR culture are discussed.

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 N 6-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.

Biotechnological Interventions for Ginsenosides Production.

Ginsenosides are secondary metabolites that belong to the triterpenoid or saponin group. These occupy a unique place in the pharmaceutical sector, associated with the manufacturing of medicines and dietary supplements. These valuable secondary metabolites are predominantly used for the treatment of nervous and cardiac ailments. The conventional approaches for ginsenoside extraction are time-consuming and not feasible, and thus it has paved the way for the development of various biotechnological approaches, which would ameliorate the production and extraction process. This review delineates the biotechnological tools, such as conventional tissue culture, cell suspension culture, protoplast culture, polyploidy, in vitro mutagenesis, hairy root culture, that have been largely implemented for the enhanced production of ginsenosides. The use of bioreactors to scale up ginsenoside yield is also presented. The main aim of this review is to address the unexplored aspects and limitations of these biotechnological tools, so that a platform for the utilization of novel approaches can be established to further increase the production of ginsenosides in the near future.

Biotechnological advancements in Catharanthus roseus (L.) G. Don.

Catharanthus roseus (L.) G. Don, also known as Madagascar periwinkle or Sadabahar, is a herbaceous plant belonging to the family Apocynaceae. Being a reservoir for more than 200 alkaloids, it reserves a place for itself in the list of important medicinal plants. Secondary metabolites are present in its leaves (e.g., vindoline, vinblastine, catharanthine, and vincristine) as well as basal stem and roots (e.g., ajmalicine, reserpine, serpentine, horhammericine, tabersonine, leurosine, catharanthine, lochnerine, and vindoline). Two of its alkaloids, vincristine and vinblastine (possessing anticancerous properties), are being used copiously in pharmaceutical industries. Till date, arrays of reports are available on in vitro biotechnological improvements of C. roseus. The present review article concentrates chiefly on various biotechnological advancements based on plant tissue culture techniques of the last three decades, for instance, regeneration via direct and indirect organogenesis, somatic embryogenesis, secondary metabolite production, synthetic seed production, clonal fidelity assessment, polyploidization, genetic transformation, and nanotechnology. It also portrays the importance of various factors influencing the success of in vitro biotechnological interventions in Catharanthus and further addresses several shortcomings that can be further explored to create a platform for upcoming innovative approaches. KEY POINTS: • C. roseus yields anticancerous vincristine and vinblastine used in pharma industry. •In vitro biotechnological interventions prompted major genetic advancements. • This review provides an insight on in vitro-based research achievements till date. • Key bottlenecks and prospective research methodologies have been identified herein.

Role of ethylene crosstalk in seed germination and early seedling development: A review.

Seed germination and early seedling development are two critical phases in plant lifecycle that largely determine crop yield. Phytohormones play an essential role in governing these developmental processes; of these, ethylene (ET; C2H4), the smallest gaseous hormone, plays a major role via crosstalk with other hormones. Typically, the mechanism of hormone (for instance, auxin, cytokinins, ET, and gibberellins) action is determined by cellular context, revealing either synergistic or antagonistic relations. Significant progress has been made, so far, on unveiling ET crosstalk with other hormones and environmental signals, such as light. In particular, stimulatory and inhibitory effects of ET on hypocotyl growth in light and dark, respectively, and its interaction with other hormones provide an ideal model to study the growth-regulatory pathways. In this review, we aim at exploring the mechanisms of multifarious phenomena that occur via ET crosstalk during the germination of seeds (overcoming dormancy), and all through the development of seedlings. Understanding the remarkably complex mechanism of ET crosstalk that emerges from the interaction between hormones and other molecular players to modulate plant growth, remains a challenge in plant developmental biology.

Effects of some gelling agents and their concentrations on conversion of oil palm polyembryoids into plantlets.

Oil palm, a tropical plant with an economic life of 20-25 years, is on high demand since its oil (palm oil) is now considered to be the world's most consumed oil. Despite the high potential for the use of clonal materials, the tissue culture technique for oil palm is difficult and laborious. One of the key steps of the process is the conversion of polyembroids into plantlets. Gelling agent has been implicated to play a role in ensuring the conversion of oil palm polyembryoids into complete plantlets. In the present study, for the first time, we report the effects of two types of common gelling agents, Agar Type 900 and Gelrite®, for enhanced conversion of oil palm polyembryoids into plantlets. Polyembryoids, developed from embryonic calli, were cultured and incubated on Murashige and Skoog semisolid media supplemented with Agar (Type 900) at 8-12 g/l or gellan gum (Gelrite®) 1.5-3.5 g/l. The effects of gelling agents on polyembryoid conversion was assessed based on the percentages of viability, survival, and polyembryoids that swelled, enlarged, and turned green, as well as on the basis of morphological characteristics, viz, number of shoots, leaves, roots, secondary somatic embryos, and callus formation. Based on the results of this study, in comparison to Agar Type 900, the Gelrite® with 3.5 g/l concentration was chosen as an effective gelling agent for conversion of polyembryoids into plantlets, since it resulted in 100% survival with 53.3% completely developed plantlets (multiple shoots with roots). The successful conversion of polyembryoids into plantlets achieved in this study, using the optimized gelling agent could be useful for pre-storage or post-storage conversion in many other plant species as well.

Coleus forskohlii: advancements and prospects of in vitro biotechnology.

Coleus forskohlii syn. Plectranthus barbatus is a popular medicinal plant belonging to the family Lamiaceae and order Lamiales. The leaf and root extracts can be utilized for the treatment of various ailments like bronchitis, asthma, hay fever, angina and abdominal disorders. The major metabolite that is found exclusively in the cork cells of the root in C. forskohlii is forskolin, which is used commercially for the treatment of glaucoma, asthma and several heart ailments. The essential oil extracted from the tubers of the plant also exhibits anti-microbial properties. The present review recounts the existing reports on biotechnological approaches like direct, indirect organogenesis and somatic embryogenesis for mass propagation of plantlets; the amelioration of forskolin production through cell suspension and genetic transformation as well as slow growth storage for germplasm conservation. Additionally, the unexplored arenas and the prospective novel approaches are also addressed in this review that can be utilized in designing new experiments in near future on this plant.