Antioxidant actions of thymol, carvacrol, 6-gingerol, zingerone and hydroxytyrosol

Plant tissue culture has become one of the fundamental tools of plant science research. It is extensively employed in the production, conservation and improvement of plant resources. The presence of somaclonal variation in populations derived from tissue culture is affecting the use of tissue culture negatively and has remained a major problem. Conversely, it is a source of new desirable clones/variants with better agronomic traits. In this review, we summarize the possible causes, detection methods and desirability of variants. Somaclonal variation is one of the most researched and reviewed topics. Hence, we restricted ourselves to outlining various examples which may be used as important references for researchers who intend to identify and/or characterize somaclonal variants while using tissue culture for research and production. Emphasis is placed on the negative effects of somaclonal variation. However, this review also includes examples of some useful variants generated as a result of somaclonal variation.

Somaclonal variation in plants: causes and detection methods

In vitro manipulation and propagation of medicinal plants

Coarse and fine regulation of wheat yield components in response to genotype and environment

India is the second largest producer of wheat in the world, with production hovering around 68–75 million tons for past few years. The latest estimated demand for wheat production for the year 2020 is approximately 87.5 million tons, or about 13 million tons more than the record production of 75 million tons harvested in crop season 1999–2000. Since 2000, India has struggled to match that record production figure and thus faces a critical challenge in maintaining food security in the face of its growing population. The current major challenges facing future wheat production in India are increasing heat stress; dwindling water supplies for irrigation; a growing threat of new virulence of diseases such as wheat rusts (yellow, brown, and black) and leaf blight; continuous adoption of rice-wheat systems on around 11 million hectares; changes in urbanization patterns, and demand for better quality wheat. In addition, the threat posed by the new stem rust race Ug99 can not be underestimated. The wide gap (around 2.5 t/ha) between the potential and harvested yield in the eastern Gangetic Plains also cries out for solutions. Addressing issues related to different stresses will require harnessing genes discovered in landraces and wild relatives following conventional as well as non-conventional approaches. For effective technology delivery in areas that suffer from poor linkages with farmers, participatory research needs to be strengthened. The future germplasm requirements from a dependable collaborator such as CIMMYT are largely being dictated by the above factors.

Wheat improvement in India: present status, emerging challenges and future prospects

A mass in vitro propagation system for Bacopa monniera (L) Wettst (Scrophulariaceae), a medicinally important plant, has been developed A range of cytokinins have been investigated for multiple shoot induction with node, internode and leaf explants Of the four cytokinins (6-benzyladenine, thidiazuron, kinetin and 2-isopentenyladenine) tested thidiazuron (68 μM) and 6-benzyladenine (89 μM) proved superior to other treatments Optimum adventitious shoot buds induction occurred at 68 μM thidiazuron where an average of 93 shoot buds were produced in leaf explants after 7 weeks of incubation However, subculture of leaf explants on medium containing 22 μM benzyladenine yielded a higher number (1291) of adventitious shoot buds by the end of third subculture The percentage shoot multiplication (100%) as well as the number of shoots per explant remained the high during the first 3 subculture cycles, facilitating their simultaneous harvest for rooting In vitro derived shoots were elongated on growth regulator-free MS medium and exhibited better rooting response on medium containing 49 μM IBA After a hardening phase of 3 weeks, there was an almost 100% transplantation success in the field

Comparative studies of cytokinins on in vitro propagation of Bacopa monniera

A number of factors that are known to influence genetic transformation were evaluated to optimizeAgrobacterium-mediated transformation of hypocotyl explants of cauliflower variety Pusa Snowball K-1. The binary vector p35SGUSINT mobilized intoAgrobacterium strain GV2260 was used for transformation and transient GUS expression was used as the basis for identifying the most appropriate conditions for transformation. Explant age, preculture period, bacterial strain and density were found to be critical determinants of transformation efficiency. Using the optimized protocol, the syntheticcryIA(b) gene was mobilized into cauliflower. Molecular analyses of transgenics established the integration and expression of the transgene. Insect bioassays indicated the effectiveness of the transgene against infestation by diamondback moth (Plutella xylostella) larvae.

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Agrobacterium-mediated transformation of cauliflower: optimization of protocol and development of Bt-transgenic cauliflower.

A protocol is described for rapid and large-scale in vitro clonal propagation of the valuable medicinal herb Centella asiatica (L) by enhanced axillary bud proliferation in nodal segments isolated from mature plants Although bud break was dependent on BA supply, the synergistic combination of 222 μM BA and 268 μM NAA induced the optimum frequency (91%) of shoot formation as well as shoot number (4 to 5 shoots per node) Subculturing of nodal segments harvested from the in vitro derived axenic shoots on the multiplication medium enabled continuous production of healthy shoots with similar frequency MS medium supplemented with 67 μM BA and 288 μM IAA was found most suitable for shoot elongation Rooting was highest (90%) on full-strength MS medium containing 246 μM IBA Micropropagated plants established in garden soil were uniform and identical to the donor plant with respect to growth characteristics This micropropagation procedure could be useful for raising a stock of genetically homogenous plant material for field cultivation

Micropropagation of Centella asiatica (L.), a valuable medicinal herb

A mass in vitro propagation system devoid of growth regulators for Bacopa monniera (L.) Wettst., a traditional Indian medicinal plant, has been developed. Direct shoot bud regeneration was induced by culturing internode and leaf explants on Murashige and Skoog's (MS) medium supplemented with an antibiotic (trimethoprim) or a fungicide (bavistin). Bavistin showed a marked cytokinin-like activity, as evident from high number of shoot buds induced in node, internode and leaf explants. Optimum adventitious shoot buds induction occurred at 300 mg/l bavistin from internode explants. In vitro regenerated shoots were elongated and rooted before transferred to field with 85% survival. The regeneration protocol developed in this study illustrates the usefulness of additives for mass propagation and germplasm conservation of B. monniera.

Shoot bud regeneration from different explants of Bacopa monniera (L.) Wettst. by trimethoprim and bavistin

Tissue cultures from mature seeds of Vicia hajastana Grossh (2n = 10) were maintained in liquid B5 medium with 4.5 × 10−6 M 2,4-D. Initially the cultures had a very low frequency of diploid cells, ...

B. D. Singh

Papers

Comparative studies of cytokinins on in vitro propagation of Bacopa monniera

Agrobacterium-mediated transformation of cauliflower: optimization of protocol and development of Bt-transgenic cauliflower.

Micropropagation of Centella asiatica (L.), a valuable medicinal herb

Shoot bud regeneration from different explants of Bacopa monniera (L.) Wettst. by trimethoprim and bavistin

Selection pressure in cell populations of vicia hajastana cultured in vitro