Suprabuddha Kundu

Synthetic seed production of medicinal plants: a review on influence of explants, encapsulation agent and matrix

The present review illustrates the implementation of synthetic seed technology for mass propagation and short-term storage of several medicinal plants, popularly grown throughout the world. Biotechnology-based research with special reference to in vitro plant cell and tissue culture intervention created a new outlook in terms of mass propagation, germplasm storage and cryoconservation, production of secondary metabolites as well as genetic transformation. Synthetic seed technology involving alginate encapsulation of in vitro or in vivo generated explants proved to be a competent system to deal with multiplication, storage and exchange of seedless medicinal plants having traits of choice that are intricate to propagate via conventional approach. Nevertheless, optimization of production, storage and exchange of synthetic seeds are influenced by several factors. Manipulation of those factors such as explant selection, encapsulating agent and matrix determined the success of synthetic seed technology in medicinal plants. The present review elucidates an outline of past progress, present status and future prospects of synthetic seed technology intervention in medicinal plants with special emphasis on the factors which determine the success of this technology.

Cryopreservation of Forest Tree Seeds: A Mini-Review

Since forest trees form the basis of forest ecosystem, their prolong subsistence is crucial for various flora and fauna. The foremost challenges to sustain the forest ecosystem comprise of the declining forest tree population accompanied with structural changes due to afforestation and exploitation of forest area, environment changes, pests, pollution, and introgressive hybridization. For ex situ conservation approach, in vitro techniques encompass basic role for conserving tree genetic resources, predominantly where natural propagules like recalcitrant seed might not be appropriate for long-term conservation. The practice includes restricted growth techniques, conventional micropropagation, production and storage of synthetic seeds, and cryopreservation. Even though these practices have been applied chiefly to herbaceous species, but recently, woody species were also focused upon. Key conceptions, challenges and techniques for forest tree seed conservation are discussed briefly in this review with special emphasis on some successful cryopreservation approaches for long-term storage.

Artificial polyploidy in medicinal plants: Advancement in the last two decades and impending prospects

Medicinal plants are in huge demand since the consumption is widespread and ever-increasing globally. The conventional breeding programs are generally environmental dependent; prone to different biotic and abiotic stresses as well as the secondary metabolite content is too low to harvest. In this context, developing polyploid individuals artificially would be a remarkable approach to increase vigor and attain this objective. Polyploids often exhibit some morphological features that are different or greater in forms than their diploid progenies. Polyploidization can be induced by quite a few antimitotic agents. The most frequently used antimitotic chemicals are colchicine, trifluralin, and oryzalin. The whole method of induced chromosome doubling consists of a series of steps, including an induction phase, regrowth phase, and a confirmation technique to evaluate the rate of achievement. The induction phase depends on different factors, such as explant types, antimitotic agents, its different concentrations, and exposure durations. To evaluate the accomplishment of polyploidization, morphological or anatomical observations are recorded as a rapid method. However, chromosome count and flow cytometry are the most eminent method for absolute confirmation. Despite significant prospects of polyploidization, there has been very little research on medicinal plants. The current review gives an overview of the different parameters of in vitro chromosome doubling, the history of the technique, and progress made over the last two decades.

Neoteric trends in tissue culture-mediated biotechnology of Indian ipecac [Tylophora indica (Burm. f.) Merrill]

Tylophora indica (Burm. f.) Merrill, an ethno-pharmacologically important perennial climber of Asclepiadaceae, is commonly known as Antamul or Indian ipecac. It is essentially accredited for its medicinal properties owing to its wide range of alkaloids in the form of bioactive secondary metabolites, such as tylophorine, tylophorinine, and tylophorinidine. Accelerated mass propagation of Tylophora is challenging because of its reduced seed germination frequency that consequently headed the pursuit for efficient protocols on in vitro propagation for the large-scale regeneration, conservation as well as sustainable supply of quality propagules. Ample tissue culture-mediated biotechnological investigations have been carried out on this medicinal plant till date and several micropropagation protocols have been standardized as well. The present review compares between several typical methods as well as factors, involving on direct and indirect organogenesis of Tylophora along with various up-to-date and modified techniques such as somatic embryogenesis, protoplast culture, synthetic seed production, genetic transformation, and in vitro interventions for the secondary metabolite production that have been reported in last two decades. This compilation will allow assessing the achievements and trends of Tylophora research so far, as well as will advance the research more rapidly, since many aspects, basic and applied, have yet to be explored.

In vitro biotechnological approaches on Vanilla planifolia Andrews: advancements and opportunities

In vitro biotechnological advancement of Vanilla plays a major role in germplasm conservation, genetic engineering, accelerated clonal multiplication and production of disease-free plants with enviable aromatic properties. Several attempts have been taken place for the establishment of efficient in vitro protocol for Vanilla in the past few decades. Optimization of various conditions during different phases of micropropagation, for instance development of in vitro aseptic cultures, multiple shoot regeneration, rooting and acclimatization of the plantlets are discussed in this review. In addition to basic micropropagation techniques, various other in vitro biotechnological applications such as clonal fidelity assessment, genetic transformation, synthetic seed technology and cryopreservation are also highlighted. Apart from the existing data, applied aspects like embryo rescue, mutation breeding, genetic engineering, protoplast fusion, somaclonal variation, in vitro enhancement of vanillin production through cell suspension culture, hairy root culture or bioreactors and cryopreservation need to be investigated further. Overall, the current review gives a synopsis on progress and prospect of in vitro culture of Vanilla.

Cryopreservation of Medicinal Herbs: Major Breakthroughs, Hurdles and Future

Throughout the advancement of human civilization, medicinal plants have contributed an immense role. The resources for traditional medicines and most of the modern medicines are obtained from medicinal plants. With the ever-increasing requirement for secondary metabolites, the medicinal plants are exploited all over the world, leading to the threat of their extinction. To combat the situation, there is an urgent need to establish a plan for their long-term conservation. Storage under in vitro cultures, though advantageous, is costly and susceptible to microbial contamination and somaclonal variation. The most competent and economical technique for long-term conservation is cryopreservation (in liquid nitrogen at −196 °C). Traditional techniques of cryopreservation were relied on freeze-induced dehydration and applied for conserving shoot apices and undifferentiated in vitro cultures of cold-tolerant medicinal plant species. However, ice crystal formation usually occurs inside the cell, which is detrimental to cellular structure integrity. As a result, vitrification-mediated new cryopreservation techniques were efficiently employed with all types of the explant. Besides, only small number of medicinal plants could be cryopreserved for their germplasm conservation, and continued efforts to establish cryopreservation protocols for a large array of medicinal plant species are needed. The objective of the present book chapter is to appraise the work carried out in the last one decade employing the diverse cryopreservation methods for the conservation of medicinal plants.

Thidiazuron-Induced Protocorm-Like Bodies in Orchid: Progress and Prospects

Thidiazuron (N-phenyl-N′-l,2,3-thidiazol-5-ylurea, TDZ) is a substituted phenylurea chemical compound that was initially produced for mechanical harvesting of cotton bolls. Since recent past, it has become well known as a successful plant growth regulator (PGR) in plant cell, tissue and organ culture. The unique property of TDZ mimicking both auxin and cytokinin stimulates organogenic and callogenic growth of explants. In this chapter, numerous of such potentials are discussed, considering the recently published reports on characterization of TDZ-induced orchid protocorm-like bodies (PLBs) and their subsequent conversion. The summarized results clearly exhibit that TDZ significantly influences diverse culture responses starting from induction of PLB from a wide array of explants, rate of shoot formation, shoot number per explant and the time duration needed for PLB formation compared to other PGRs. A very low concentration (<1 μM ) of TDZ is much effective in comparison to many other PGRs; though TDZ may hold back shoot elongation after culturing for long duration in the same medium. The unwanted side effect of TDZ is that the fasciated shoots are formed occasionally in some orchid species after prolonged culture. Besides the minor disapproval, the high proliferative activity and positive response to organogenesis, TDZ has evolved to be the most active cytokinin-like PGR for in vitro regeneration of orchid species.

Fundamental Facets of Somatic Embryogenesis and Its Applications for Advancement of Peanut Biotechnology

Peanut (Arachis hypogaea Linn.) is one of the most vital crops providing predominant supply of protein, vitamins and fats, along with other necessary nutrients. Various factors, responsible for induction, maintenance, multiplication of the embryogenic cultures, as well as maturation and conversion of somatic embryos (SEs) into complete plants have been discussed in this review. In order to find the present trends and thriving methodologies for the development of somatic embryogenesis, a lot of emphasis has been given to the economically important species. It has been reported that from young meristematic tissues like immature embryos and leaves of legumes, SE can be induced comparatively in a easier way. However, there are multiple constraints that limit the usage of somatic embryogenesis-based biotechnological applications on legumes, such as low rate of embryo formation, reduced germination, inadequate conversion into plantlets and somaclonal variation. These hindrances, nonetheless, may significantly be diminished in future, since the effective plant growth regulators with specific morphogenic targets are becoming available for experimental purposes. Existing reports reveal that somatic embryogenic systems, having superior germination and regeneration ability shall have direct usage in large-scale propagation and several other crop improvement features. With increasing knowledge of different morphogenic processes, involving differentiation of zygotic embryos, it is possible that improvement of this technology having practical efficacy may be applicable for the important peanut genotypes.

Conserving Biodiversity of a Potent Anticancer Plant, Catharanthus roseus Through In Vitro Biotechnological Intercessions: Substantial Progress and Imminent Prospects

In vitro interventions are exceedingly advantageous for large-scale propagation and conservation of plant biodiversity, involving endangered plant species as well as elite genotypes that produce commercial products. The importance of Catharanthus roseus in the treatment of several kinds of cancers such as skin cancer, breast cancer, lymph cancer, leukemia, and Hodgkin’s disease warrants persistent attention for the biotechnological improvement of this plant. Therefore, the present chapter provides an overview of the state of knowledge on the current use of biotechnological tools applied on propagation, genetic enhancement and conservation of C. roseus besides its implications to improve the plant in the future. Explants from this clonally propagated species can be easily harvested under field conditions using in vitro approaches. In vitro micropropagation methods affirm the accelerated duplication of disease-free material. Medium-term conservation can be attained by slow growth of plant material leading to the increased time interval between subsequent cultures. Synthetic seeds are also considered for short- to mid-term conservation and germplasm exchange. For long-term conservation, cryopreservation (in liquid nitrogen at −196 °C) permits storing of C. roseus germplasms for extended periods exclusive of any clonal variation. Besides micropropagation and conservation, the enhancement of secondary metabolites through hairy root culture and cell suspension culture and the use of molecular markers to detect somaclonal variation in C. roseus are also highlighted in this chapter.