Bijaya Pant

Developmental stage-dependent differential gene expression of superoxide dismutase isoenzymes and their localization and physical interaction network in rice ( Oryza sativa L.)

Superoxide dismutase (SOD) isoenzymes are essential for scavenging excess reactive oxygen species in living organisms. So far, expression pattern of SOD isoenzymes genes along leaf development plus their sub-cellular localization and physical interaction network have not yet been clearly elucidated. Using multiple bioinformatics tools, we predicted the sub-cellular localizations of SOD isoforms and described their physical interactions in rice. Using in silico approaches, we obtained several evidences for existence of seven SOD genes and a SOD copper chaperone gene. Their transcripts were differentially expressed along with different developmental stage of rice leaf. Finally, we performed quantitative real time-polymerase chain reaction (qRT-PCR) to validate in silico differential expression pattern of SOD genes experimentally. Expression of two cytosolic cCuZn-SODs was high during the whole vegetative stage. Two plastidic Fe-SODs were found and their expression levels were very low and started to increase from the late vegetative stage. Their expression patterns were very similar to each other, indicating the formation of heterodimer. However, their expression patterns are different from those for ArabidopsisFe-SODs. The expression of pCuZn-SOD was very high in the early developmental stage, but qRT-PCR results were different, which remains for further study. From the results on the differential expression of SOD genes, we can understand the role of each SOD gene and even predict their role under certain circumstances based on in silico analysis.

In vitro germination and propagation of a threatened medicinal orchid, Cymbidium aloifolium (L.) Sw. through artificial seed

ABSTRACT Objective To study the in vitro germination and plantlet regeneration from artificial seeds of Cymbidium aloifolium (C. aloifolium), a highly threatened medicinal orchid of Nepal. Methods Artificial seeds were produced in vitro by encapsulation of protocorms with 4% sodium alginate and 0.2 mol/L calcium chloride solution. In vitro germination and plantlet regeneration of the artificial seeds were tested by culturing them on different strength of Murashige and Skoog (MS) liquid media (0.25, 0.5 and 1.0) and MS liquid medium supplemented with 0.5 mg/L benzyl amino purine and 0.5 mg/L naphthalene acetic acid. Freshly produced artificial seeds were stored up to 28 d at 4 oC. In order to check the viability, storage artificial seeds were treated with five different sterilization techniques (T1, T2, T3, T4, T5) and inoculated on full strength (1.0) of MS liquid medium after each 7 d of interval upto 28th days. Results The highest percentage of germination (100%) of artificial seed was obtained on quarter (0.25), half (0.5) and full (1.0) strength of MS liquid medium. Experimentally, full strength of MS liquid medium was more effective for earlier seedling development of C. aloifolium. Artificial seeds were successfully stored at 4 oC till 28th days. Treatments T1 and T2 showed 97.5% viability of storage artificial seeds and hence considered as the most effective sterilization techniques to recover the plant from storage artificial seeds. Plantlets developed from artificial seeds were successfully acclimatized in potting mixture containing cocopeat, litter and sphagnum moss with 85% survival rate. Conclusions The present study revealed that artificial seeds are the good alternative explants for in vitro mass propagation and short term conservation of C. aloifolium.

Application of Plant Cell and Tissue Culture for the Production of Phytochemicals in Medicinal Plants

Approximately 80% of the world inhabitants depend on the medicinal plants in the form of traditional formulations for their primary health care system well as in the treatment of a number of diseases since the ancient time. Many commercially used drugs have come from the information of indigenous knowledge of plants and their folk uses. Linking of the indigenous knowledge of medicinal plants to modern research activities provides a new reliable approach, for the discovery of novel drugs much more effectively than with random collection. Increase in population and increasing demand of plant products along with illegal trade are causing depletion of medicinal plants and many are threatened in natural habitat. Plant tissue culture technique has proved potential alternative for the production of desirable bioactive components from plants, to produce the enough amounts of plant material that is needed and for the conservation of threatened species. Different plant tissue culture systems have been extensively studied to improve and enhance the production of plant chemicals in various medicinal plants.

Production of virus-free orchid Cymbidium aloifolium (L.) Sw. by various tissue culture techniques.

Orchids are affected by many viruses resulting in poor growth, yield and quality, and an overall decline in population. Cymbidium mosaic virus (CymMV) is one of the common orchid viruses found in Cymbidium species but it infects different orchid genera. In this study Cymbidium aloifolium was propagated in vitro using MS medium at different strength (1.0, ½, and ¼) with or without 0.5 mg/l BAP (6-benzylaminopurine) and 0.5 mg/l NAA (Naphthalene acetic acid). To provide disease-free planting material, source plant for in vitro propagation needs to be screened for pathogenic viruses. In the present study, in vivo-grown source (mother) plants and tissue culture-derived plants of C. aloifolium were tested for CymMV virus using Double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA). All the tissue cultured plants were found to be 100% virus-free whereas the in vivo grown source plants were highly affected by CymMV virus (83.33%). The virus-free in vitro plantlets were multiplied in large scale and then acclimatized on earthen pot containing a mixture of cocopeat, litter and clay in the ratio of 3:2:1. Eighty five percent of acclimatized plantlets survived making this method an efficient mass production system for high quality virus-free C. aloifolium for commercial floriculture and germplasm preservation.

A MATLAB program for quick estimation of characteristics of piezoresistive pressure sensors

Piezoresistive pressure sensors are one of the most popular types of sensors used for pressure sensing. These sensors consist of a diaphragm and piezoresistors. The characteristics of the pressure sensor can be modelled using analytical expressions for thin plates and the theory of piezoresistance to obtain a quick guideline and estimation of critical parameters of pressure sensor such as linearity and sensitivity, before detailed finite element method analysis. In the present work, a MATLAB® based program has been developed for determining the deflection of diaphragm, x- and y- directed stresses of the diaphragm, the relative change in resistance at the piezoresistor locations and eventually the sensitivity and linearity of the sensor. Finally, the use of the program is demonstrated through a case study.Piezoresistive pressure sensors are one of the most popular types of sensors used for pressure sensing. These sensors consist of a diaphragm and piezoresistors. The characteristics of the pressure sensor can be modelled using analytical expressions for thin plates and the theory of piezoresistance to obtain a quick guideline and estimation of critical parameters of pressure sensor such as linearity and sensitivity, before detailed finite element method analysis. In the present work, a MATLAB® based program has been developed for determining the deflection of diaphragm, x- and y- directed stresses of the diaphragm, the relative change in resistance at the piezoresistor locations and eventually the sensitivity and linearity of the sensor. Finally, the use of the program is demonstrated through a case study.

An Overview on Orchid Endophytes

Orchids, one of the most beautiful and diverse plant species in the nature, are a bit of a mystery for their seeds lack endosperm and they must depend on endophytes for germination, growth and adaptation. Naturalists and even the general public are drawn to orchids for their ornamental, medicinal and food value. In their keenness to harvest them, collectors have rendered many orchid species threatened or even endangered. Recent research into orchids, which are mycohetetrophic plants, has focused on isolation and identification of the mycorrhizal and non-mycorrhizal endophytes that directly or indirectly contribute to the growth and development of orchids as well as the production of valuable secondary metabolites. This article considers both the role such endophytes play and explains how such symbiotic partner scan be used in the plant tissue culture technique to help conserve and even commercialize various species of orchid.

In vitro Mass Propagation of an Epiphytic Orchid, Cymbidium aloifolium (L.) Sw., through Protocorm Culture

Aim: To develop a protocol for in vitro propagation of Cymbidium aloifolium, a threatened orchid highly used for medicinal purpose through protocorm culture. Place and Duration of Study: Tissue culture Laboratory, Plant Biotechnology Unit, Department of Botany, Tribhuvan University, Kirtipur, Nepal, between November 2013 to December 2014. Methodology: Small, green and globular protocorms with 0.1-0.3 cm diameter were subjected to grow individually on solidified Murashige and Skoog (MS) basal medium and MS medium supplemented with various concentration of plant growth regulators, 6-Benzylaminopurine (BAP, 0.5; 1; 1.5; 2 mg/l) or α-Naphthalene Acetic Acid (NAA, 0.5; 1 mg/l) or their combination. Six replicates were used for each concentration. The data for development of shoot and root from each protocorm culture were recorded in every two weeks for upto six month. Results: Almost all conditions favoured multiplication but MS medium fortified with BAP (1 mg/l) and NAA (1 mg/l) resulted in maximum induction of rootless healthy shoots with an average value of 8-9 shoots per culture. On this medium, shoot multiplication was initiated after 9 weeks of culture Original Research Article Regmi et al.; BJI, 19(1): 1-6, 2017; Article no.BJI.34891 2 whereas MS medium fortified with BAP (2 mg/l) and NAA (0.5 mg/l) was found to be most effective condition for the shoot multiplication along with well developed roots. Conclusion: MS medium supplemented with high concentration of BAP and low concentration of NAA was found to be efficient for maximum multiplication of shoot and root. The in vitro developed healthy rooted plantlets of C. aloifolium were successfully acclimatized in green house on potting mixture containing cocopeat and moss in the ratio of 2:1. On this condition, nearly 70% of the plantlets were successfully survived. Hence, this protocol might be useful for mass propagation and ex situ conservation of this orchid through protocorm culture.

Comparative study of characteristics of polysilicon pressure sensor with different diaphragm sizes and piezoresistor configurations

In this work, the fabrication and characterization of eight different polysilicon piezoresistive pressure sensors are reported. The sensors are fabricated simultaneously by putting the different designs on the same mask set and the sensitivity and non-linearity characteristics are plotted. The output responses of the different sensors are reported at three temperatures (–5, 25 and 55 °C). Out of the eight sensors with different diaphragm sizes and piezoresistor configurations, the sensor with diaphragm edge length of 1,280 µm and 2x1 configuration is found to have optimum characteristics, with good non-linearity and acceptable sensitivity. For this sensor, a sensitivity of 3.83–4.26 mV/Bar and non-linearity of <0.38 % are obtained in the pressure range of 0–30 Bar.In this work, the fabrication and characterization of eight different polysilicon piezoresistive pressure sensors are reported. The sensors are fabricated simultaneously by putting the different designs on the same mask set and the sensitivity and non-linearity characteristics are plotted. The output responses of the different sensors are reported at three temperatures (–5, 25 and 55 °C). Out of the eight sensors with different diaphragm sizes and piezoresistor configurations, the sensor with diaphragm edge length of 1,280 µm and 2x1 configuration is found to have optimum characteristics, with good non-linearity and acceptable sensitivity. For this sensor, a sensitivity of 3.83–4.26 mV/Bar and non-linearity of <0.38 % are obtained in the pressure range of 0–30 Bar.