Showing papers in "Agricultural Reviews in 2013"

Effect of mulching on crop production under rainfed condition - a review

Abstract: Mulching is an agricultural and horticultural technique in which the use of organic is involved. This technique is very useful in protecting the roots of the plants from heat, cold. Mulch is used to cover soil surface around the plants to create congenial condition for the growth. This may include temperature moderation, reduce salinity and weed control. It exerts decisive effects on earliness, yield and quality of the crop. Mulching is also applicable to most field crops. However, it is preferred in fruit orchard, flower and vegetable production, nurseries and forest where frequent cultivation is not required for raising the crops. Black plastic mulch is most commonly used in agriculture. Clear plastic mulch is used in some areas due to its increased soil warming characteristics. Research has shown that white or aluminum reflective mulch also repels aphids which spread some virus diseases in vine crops such as squash. So, mulching can be effective change in increasing horticultural crop production in water scarcity regions.

Entomopathogenic nematodes - A review

Abstract: The entomopathogenic nematodes possessing balanced biological control attributes belong to genera Steinernema and Heterorhabditis and are having mutualistic association with bacteria of the genus Xenorhabdus for Steinernematidae and Photorhabdus for Heterorhabditidae. Entomopathogenic nematodes being highly lethal to many important insect-pests, are safe to nontarget organisms and working with their symbiotic bacteria kill the insects within 24–28 hours as compared to days and weeks required for insect killing in other biological control agents. Their infective juveniles (IJs) have been reported to tolerate short-term exposure to many chemical and biological insecticides, fungicides, herbicides, fertilizers and growth regulators, hence providing an opportunity of tank-mixing and application together. Entomopathogenic nematodes are also reported to be compatible with a number of agrochemicals and their use can offer a cost-effective alternative to pest control. Only twelve species out of nearly eighty identified Steinernematids and Heterorhabditis nematode species have been commercialized. The EPNs have the great potential to be used in integrated pest management systems and work done have been reviewed in this article to facilitate the students and researchers to have an overview of the work done and proceed further to undertake the advanced research in different aspects related to entomopathogenic nematodes.

Impact of climatic factors on crop production -A review

Abstract: Agriculture always faces the risks due to various reasons. Among that climatic risks are the most important one as there are unavoidable and unexpected. Increased temperature, changed precipitation conditions and increased CO2 content in the atmosphere are the major climatic factors affecting crop production. Rise in atmospheric temperature will lead to loss of soil moisture and will increase the crop demand for water. The amount and availability of water stored in the soil will be affected by changes in both the precipitation and seasonal and annual evapotranspiration regimes. Changes in atmospheric carbon dioxide concentration can cause uncertainty in crop yields. Solar radiation also has considerable effect on photosynthesis and crop yield. The effect of interrelationship between the climatic factors like temperature, rainfall, solar radiation, CO2 concentration, etc and crop yield need to be understood to take necessary adaptation measures to maintain the crop production. This paper presents an overview of the impacts of various climatic factors on crop production.

Regulation of somatic embryogenesis in crops: A review

Abstract: ‘Somatic embryogenesis’ is a process whereby somatic cells differentiate into somatic embryos. It is regulated by several factors, including phytohormones, proteins, transcription factors, and other related substances during different stages of development. Somatic cells are not terminally differentiated and therefore regain totipotency to initiate embryo development. Although this phenomenon is well known, the detail mechanism of how hormones specify cell fate during in vitro organogenesis is still mysterious. To uncover this mechanism, several studies have been done using biochemical, biological and molecular approaches with embryo-defective mutants or somatic embryogenesis. Recent progress in plant molecular and developmental biology now allows us to establish new pathways for the transition of somatic cells to the embryogenic state. Hormone signaling plays an important role in the cell differentiation during different stages of embryogenesis. During somatic embryo induction, there is differential gene expression resulting in synthesis of new mRNAs and proteins. An array of genes activated or differentially expressed during somatic embryogenesis have been isolated. Few transcription factors have been identified from embryo-defective mutants and some regulatory factors (phenolic compounds and peptidyl growth factors) were detected from culture medium during somatic embryogenesis. In future, research on characterization of development-specific genes during somatic embryogenesis may elucidate a deeper insight in understanding the mechanisms involved during differentiation of somatic cells and phenotypic expression. This review summarizes current understanding of the cellular and molecular aspects of SE and various regulating factors affecting it.

Studies on pre and post-harvest treatments for extending shelf life in onion - a review.

Abstract: In India, presently about 35 to 40 per cent of the onion is estimated to be lost as postharvest losses during various operations including handling and storage. Pre-harvest sprays of growth regulators viz., cycocel, ethylene compounds and fungicides play a crucial role in enhancement of shelf life in onion. The curing techniques like neck cut in onion bulbs and exposure to onion bulbs in gamma radiation for storage are proved to be useful techniques in delaying sprouting and their subsequent deterioration resulting in improved shelf life. Packaging and storage techniques also influence the shelf life of onion bulbs during storage. There is a sequence of physiological and biochemical changes occur in onion bulbs during above post harvest handling operations. The literature pertaining to the above aspects during post harvest handling and storage of onion and garlic bulbs are reviewed in this paper.

BLACK ROT- A DEVASTATING DISEASE OF CRUCIFERS: A Review

Abstract: Crucifers are popular temperate vegetables and occupy important place among vegetables in India as well as in the world. India is the second largest producer of crucifers in the world. These crops are affected by many diseases during the growing period which reduce the yield as well as the quality of the produce. Amongst all the diseases, black rot caused by Xanthomonas campestris pv. campestris (Pam.) Dowson is the most destructive one causing heavy losses. The disease affects primarily above ground parts of the plant at any stage of growth and causes high losses, in yield and quality especially in tropical and subtropical regions during the rainy season. All vegetables in the cruciferous family, including broccoli, brussels sprouts, cabbage, cauliflower, chinese cabbage, kale, mustard, radish, rutabaga, and turnip are susceptible to black rot. Many cruciferous weeds such as Shepherd’s Purse, wild mustard, and yellow rocket are also known to be hosts of this pathogen. The pathogen is seed borne and also survives in the infected plant debris as well as cruciferous weed hosts. The disease can be managed through cultural practices, resistant hosts, seed treatment with hot water and antibiotics, fungicides, biological control as well as chemical control methods.

Quality parameter requirement and standards for malt barley-A review

Abstract: Barley is fourth largest cereal crop of the world. It contributes nearly 7 per cent to the global cereal production. The major industrial use (20-25 per cent) of barley is for malting purposes in India. The annual requirement of barley for malting purposes is on continuous rise in recent years. Malt is used for brewing, distillation, baby foods, confectionaries, cocoa-malt based drinks and medicinal syrups etc. The availability of barley for malting is not a problem, but whatever barley is available is of very poor quality and not meeting the minimum standards of malting quality. The present discussion outlines the different grain and malt parameters, which are desired for better malt recovery and quality of the malt, needed for various products. This can be of help to the researchers, industry, raw material supplier and farmers.

Weed management in rapeseed-mustard - a review

Abstract: Rapeseed-mustard is an important group of edible oilseed crops in India Technological advancement in rapeseed-mustard production has resulted in increased productivity But many biotic stresses such as weeds cause severe yield losses up to 45% in rapeseed-mustard They reduce crop productivity and quality by competing with crop plants for available nutrients, water, land and light resources and also influence the agro-ecosystem A variety of weeds affects these crops but the extent of damage in terms of yield and resources is location specific Many of the weeds are specific to crop and/ or location, Orobanche aegytptica is becoming great menace in rainfed areas of Rajasthan, Madhya Pradesh and Haryana, whereas, Chenopodium, Asphodelus, Melilotus and Trianthema spp cause serious yield losses in other areas Unlike other oilseed crops, mustard suffers more from weed competition in early growth stages especially between 20-40 days after sowing The weed management in mustard is done by both cultural and herbicidal approaches Different dinitroaniline herbicides are commonly used to eliminate weed species and most of these are effective against only narrow range of weed species Thus, integration of herbicide at critical growth stages with one or two hand weeding at proper time for improving the weed suppressing effect of crop gives significant improvement in crop yield Economic analysis revealed that fluchloralin and pendimethalin alone or in combination with hand weeding at 30 days after sowing was the most economical

Host plant resistance to insect pests of grain legumes - a review.

Abstract: Grain legumes are important source of dietary protein in tropical region and insect pests cause considerable damage to these crops. Development of resistant varieties in legume crops is an important component in integrated pest management strategies. Though insecticides are effective against sucking pests and pod borer complex, development of insecticide resistance, residues in short duration crop produces and environment hazards demand alternative eco safe method of management. The chapter reviews the development and studies on host plant resistance in major grain legumes against pod borer complex Maruca vitrata, Helicoverpa armigera, etc. and major sucking pests. The mechanisms of resistance, factors responsible for the resistance are discussed in this paper.

Bamboo Forest Resources of India and its Role in Food Security - A Review

Abstract: Bamboo, the fastest growing plant, is estimated to cover 8.96 million ha of the total 63.3 million ha forest area of India. The plant is intricately associated with humans from times immemorial. Though popularly known for industrial usage, a lesser known fact of bamboos is the utilization of its juvenile shoots as food that can be consumed fresh, fermented, canned or pickled. Bamboo shoots have high nutritive value containing low fats and cholesterol and high amount of carbohydrate, proteins, minerals and dietary fibres. It holds great promise for utilization as health food because of presence of bioactive compounds which is found to have medicinal properties. Being one of the fastest growing plants, its shoots can be utilized for feeding the ever increasing human population and also because of its nutritional and therapeutic values, the shoots can be used to make up for the dietary deficiencies of nutrients in the diet.

Role of remote sensing and gis in land resource inventory- a review

Abstract: Soil and water are important natural resources needed for the sustained quality of human life and the foundation of agricultural development. Efficient management of these natural resources is the major challenge for the agricultural scientists, planners, administrators and farmers to ensure food, water and also environmental security for the present and future generations. Soil is the essence of life. An intimate knowledge on their characteristics, classification, location, extent and distribution, potentials and problems is a prerequisite for developing rational land use planning. Soil resource inventory provides an insight into the potentialities and limitation of soil for its effective exploitation. Modern tools such as satellite Remote Sensing, Global Positioning System (GPS) and Geographical Information System (GIS) have been providing newer dimensions to monitor and manage soil resources for their effective utilization. Especially remote sensing techniques have reduced our field work to a considerable extent and soil boundaries are more precisely delineated than in conventional methods. Hence it is a highly proven technology that is effective for mapping and characterizing land resources.

Forecasting models for potato late blight management -A review

Abstract: Late blight of potato caused by Phytophthora infestans (Mont.) de Bary, is one of the most serious and devastating disease of potato world over, including India and is an important limiting factor for yield reduction in India. Management of potato late blight has always been a challenge for both scientists as well as growers. For effective management of disease, efforts should made to reduce initial inoculum (in temperate conditions) but main emphasis should be to slow down progress of disease. Hence, there is urgent need to develop some kind of disease forecast/warning service for predicting the time of appearance of disease and optimizing use of fungicides without risking the crop and human health. A disease forecasting model predicts out-break or changes in intensity of one or more diseases on the basis of information about weather, crop, pathogen(s) or some combination of the three. Various forecasting models have been developed and utilized over the years for predicting late blight of potato across the globe. Based on four weather parameters, viz. dew points, night temperature, cloudiness and rainfall to predict initial appearance of late blight in Holland. But such models are not universal in adoption but have impetus for several workers. The implementation of forecasting model for late blight of potato depends upon area specific climatic conditions.

Sustainable rural livelihood security through integrated farming systems -A review

Abstract: This is a very complex and serious problem, when share of agriculture in gross domestic product is declining, average size of land holding is contracting and number of operational holdings is increasing. It is imperative to develop strategies that enable adequate employment and income generation, especially for small and marginal farmers who constitute more than 80 percent of the farming community. Under the gradual shrinking of land holding, horizontal expansion of land based enterprises is not possible. Hence, vertical integration land based enterprises within the socioeconomic environment of the farmers will make farming more profitable and dependable. Therefore, Farming systems approach is a valuable approach to addressing the problems of sustainable economic growth for farming communities in India. Hence, integrated farming systems are viewed as a sustainable alternative to commercial farming systems particularly on marginal lands with the objective of reversing resource degradation and stabilizing farm incomes. The literature on the contribution of integrated farming systems in achieving sustainable rural livelihood security has been reviewed in this paper.

Rice bran oil- Unique gift of nature: A review

Abstract: Rice bran oil (RBO) is popular in several countries such as Japan, India, Korea, China and Indonesia as a cooking oil. It has been shown that RBO is an excellent cooking and salad oil due to its high smoke point and delicate flavor. The nutritional qualities and health effects of rice bran oil are also established. RBO is rich in unsaponifiable fraction, which contains the micronutrients like vitamin E complexes, gamma oryzanol, phytosterols, polyphenols and squalene. It is high in antioxidants namely oryzanol, tocotrienol, tocopherol and squalene with some amount of omega 3 fats. WHO, NIN and ICMR have recommended a near equal ratio of SFA( 27-33%); MUFA( 33-40%); PUFA(27-33%) in a healthy oil. Rice Bran oil is closest to this recommendation having SFA (24%); MUFA (42%); PUFA (34%). Therefore, in recent years, research interest has been growing in RBO processing to obtain good quality oil with low refining loss.

Factors affecting the sustainability of ICT intervention for agricultural development - a review.

Abstract: The donor agencies are being directly-indirectly implementing ambitious ICT interventions in developing countries with the hope for sustainable impact arising from development oriented ICT interventions. In the past, emphasis had been placed on the supply side rather than the demand side. Hence, the main focus of the interventions has been the implementation the ICT for Development project and creating infrastructure rather than understanding the impact on the society level and integration of inbuilt checks and balances for sustainability of interventions. Here attempt is made to review different factors associated with the sustainability of the ICT intervention for agricultural development. The other aim is to ponder over the achievements and the failures of ICT in the sustainable development march. Thus, the impact measures and factors of sustainability need to undertake in planning and implementation of interventions for its long term functionality.

Integrated weed management-A strategy for sustainable wheat production - A review

Abstract: Wheat is one of the important cereals contributing approximately 30-35 % to total food grain basket of the country. Wheat infested by multifarious weed flora comprising both grassy as well as broad leaf weeds causing yield reduction of 15- 40 % depending upon type and intensity of their infestation. Herbicides continue to be the most powerful, economically effective and reliable way to control weeds in wheat. Over the years, the efficacy of herbicides has started declining and there is possibility of development of cross resistance. An integrated approach, where herbicide plays a pivotal role is the only way ahead for effective weed management. Use of weed free seed, use of well rotten farm yard manure, method of sowing, seed rate, sowing time, varietal selection, amount of fertilizer application, proper herbicide selection, proper dose, time and method of herbicide application, herbicide rotation and mixture, use of adjuvant, mechanical weeding and crop rotation are the major constituents of integrated weed management. Thus, integrated weed management practices should be location and time specific by considering the weeds in a broader ecological and management context.

Papaya Mealybug Paracoccus marginatus Williams & Granara De Willink (Hemiptera: Pseudococcidae), A Current Threat to Agriculture - A Review

Abstract: Papaya mealybug, Paracoccus marginatus assumed the major pest status in India in 2009 because of its severe damage to economically important crops. It has a wide host range of over 60 species of plants. It infested the veins and the midribs of the older leaves, tender leaves and fruits and turns them yellow and later dry up. Heavy mealybug populations produce a copious amount of honey dew, which causes black sooty mould. It reduces the fruit quality and market value of this crop. Females are light greenish yellow in colour whereas an adult male are deep reddish in colour and bears one pair of wing. It takes almost 19-30 days to complete a generation and there is 11 to 13 generation per year. This pest is currently controlled using chemical, biological and cultural control techniques in an integrated pest-management system.

Carbon sequestration for mitigation of climate change - a review.

Abstract: Emission of greenhouse gases has become a matter of major concern; nations are struggling to lower the greenhouse gas emissions because of its adverse effects on life. There is dire need to lower the source size and enlarge the sinks of green house gases. Reducing CO2 concentration in the atmosphere by enhancing the rates of removal of the atmospheric CO2 through carbon sequestration is considered as one of the best climate change mitigation strategy. Carbon sequestration is the issue of international interest due to its potential impact on agriculture and climate change. Oceans, soils, geological formations, mangroves, bogs, agriculture and agro forestry serves carbon sequesters. Although intensive agriculture is a source of carbon emission, it can be converted to sink with proper management. Policies to reduce climate change using natural ecosystems to sequester and store carbon should be accompanied by technological solutions to further reduce the impacts of climate change.

Role of pathogenesis-related proteins in plant disease management -A review

Abstract: The present paper reviews one of the most important defence strategy employed by plants against pathogens. Pathogenesis-related proteins (PR-proteins) are induced in plants in response to attack by microbial or insect pests and certain stress conditions. They have been classified into several groups (PR-1 through PR-17) based on their amino acid sequences and biochemical functions. In many cases, the expression of the PR-proteins either singly or in combination appears to improve resistance to multiple phytopathogens. Transgenics with PR protein encoding genes will have a major role in plant disease management.

In vitro shoot tip grafting in citrus species- a review

Abstract: A retrospective overview of work done on the in vitro shoot tip grafting in citrus in the world was taken up. In vitro shoot tip grafting is the most reliable method to recover free citrus saplings from infected parental source. The technique of in vitro shoot tip grafting is a suitable method for the elimination of graft transmissible diseases in citrus. Preliminary studies showed that certain pathogens are difficult to be eliminate from mother plant like citrus exocortis and stubborn, which might be eliminated by a process of shoot tip grafting in-vitro . Plant obtained by micro-grafting do not have the same problems as nucellar plants such as reversion to the juvenile state, excessive thorniness, vigorous and upright habit of growth, slowness to fruiting, alternate bearing in early years and physical differences in fruit characteristics.

Stress markers in the plasma and milk of murrah buffaloes during summer

Abstract: India has acquired the distinction of being the highest milk producing country in the world since 1998 with an annual growth rate of 4-5 %. The estimated milk production in India is about 110 million tons (2008-09). Buffaloes contribute about 55 % of the total milk production and occupy an important place in the agricultural economy of India due to its better adaptability to harsh climatic conditions, tolerance to tropical diseases and survival under poor crop residue feeding and management practices (Gupta, 1997; Indian Dairyman, 2010). Inspite of this the inherent potential of buffalo productivity can be augmented by appropriate measures to alleviate heat stress. The best way to deal with heat stress is to take the managemental measures to ameliorate its detrimental effects. In the recent time a number of plasma and milk biomarkers have been identified which could be used to find out the stress condition in animals. The present review discusses the various biomarkers and their application to further augment the milk production of buffaloes under tropical climatic conditions.

Biofuel concept: prospects and challenges - a review

Abstract: In recent years, bioenergy has drawn attention as a sustainable energy source because of a combination of growing energy needs, rising oil costs, the pursuit of clean, renewable sources of energy and the desire to boost farm incomes in developed countries. There are currently few players in this field; Brazil and the United States together accounts for more than 90 per cent of global ethanol production, whereas Germany and France accounts for more than 65 per cent of global biodiesel production. However, developing countries with sub-tropical climate like India is having a comparative advantage in growing energy rich biomass. The second generation technologies could enable expansion of the range of feedstock used from the traditional sugarcane, maize and rapeseed to grasses and trees that can thrive in less fertile and more drought prone regions. Potentially adverse impacts from a rapid bioenergy expansion include upward pressure on international food prices, making staple crops less affordable for poor consumers, significant adverse effects on both land and water resources and on biodiversity. The bottleneck for producing biofuels is the supply of feed stocks and the competition of these crops for food, feed or fuel. Mitigation of potentially adverse impacts of aggressive increase in biofuel production requires a renewed focus of crop breeding for productivity improvement in crop plants.

Influence of legume crops and fallows on fertilizer nitrogen requirement and productivity of succeeding maize - a review.

Abstract: Maize being an exhaustive crop demands for higher fertilizer application, especially N fertilizer and the addition of nutrients through fertilizers is, however, far below the crop removal. Exploring low - cost agronomic practices is highly imperative in the present day agriculture to increase farmers profitability and environmental safety. Further, while devising fertilizer N recommendations to a crop it is necessary to consider cropping sequence as a whole rather than that individual crop per se because the need for nutrients by a crop would vary depending upon the preceding crop type and its inputs usage. This review provides an update on the research undertaken on productivity and nitrogen requirement of maize as influenced by preceding cropping practices.

Effect of crop-weed competition in cotton (gossypium hirsutum l.) - review

Abstract: Cotton being a long duration, wide spaced and relatively slow growing crop in early stages, is subjected to a severe weed infestation. Weeds have always been a bottleneck for crop production. Inadequate weed control at appropriate stage is considered as a major constraint for high yield. Cotton was very sensitive to weed competition in the first 60 days of crop growth. The period of weed interference, crop damage and the critical period of crop-weed competition were 30 to 60 days which occupied 50 per cent of the whole cotton growing period. Seed cotton yield loss increased with the increase in the duration of competition and maximum loss was observed due to full season competition. Weed infestation in cotton has been reported to offer severe competition and causing yield reduction to an extent of 40 to 85 per cent. Due to their high competitive ability, weeds compete for resources thereby affecting productivity of cotton. Hence, a brief review is presented on the nature of weed spectrum in cotton, competition between crops and weeds, their effect on growth and yield, quality of cotton.

Status of insect resistance to bacillus thuringiensis, mechanism and management - a review

Abstract: Bacillus thuringiensis, commonly known as Bt, a most promising alternative to synthetic insecticides, has been used as an effective bio-pesticide in agriculture since long time. Two insecticidal protein, Cyt (Cytolysins) and Cry (Crystal a-endotoxin) are the toxic substances responsible for the death of an insect. The durability of this novel insect control technology is questioned as many cases of insect population developing resistance to Bt cry proteins were observed and various mechanisms for resistance to Bt cry proteins were reported. Management of resistance in insect to Bt includes refugia, gene pyramiding and novel toxins.

Scrapie: A neuro degenerative disease in sheep -A review

Abstract: Scrapie is a unique disease whose etiology is through protein infection rather than a biological agent. Genetic polymorphism at 136, 154 and 171 codons provide the susceptibility/ resistance to the disease outbreak. PCR-SSCP has been found to be a robust technique for the identification of genetic variants because of SNP in the ORF (open reading frame) of PrP gene efficiently at low cost, evidenced by novel DNA sequences resulted from the SSCP variants. Prevalence of susceptible alleles at 136, 154 and 171 codons however did not result into the scrapie disease clinical symptoms in indigenous sheep breeds. Polymorphism at other loci in indigenous sheep could have played significant role in prevention of disease symptoms in indigenous sheep. The traditional feeding and management exclusively on range grazing without any concentrate supplementation having any animal protein might be responsible for the protection of animals from scrapie disease infection despite presence of susceptible alleles in the indigenous sheep animals.

Weed Management in Aerobic Rice - A Review

Abstract: Aerobic rice is a new way of cultivating rice that requires less water than lowland rice. Direct sown aerobic rice suffers more due to weed menace as the weeds and rice compete for growth factors together. Achieving higher rice grain yields under aerobic conditions requires better weed management practices. Hence, the aerobic rice should be focused primarily on efficient weed management to make aerobic rice cultivation more efficient in terms of returns on farmer investments and use of water resources. The promising herbicides in aerobic rice were pre-emergence pretilachlor at 0.45 kg/ha on 5 DAS + hand weeding at 45 DAS and post emergence mixture of fenoxaprop + ethoxysulfuron at 45-60 g /ha + 10-18 g/ha.

Induced moulting in layers – a review

Abstract: Poultry industry is playing the biggest role in the industries of the developing countries with respect to the capital generated by this industry as well as the fulfillment of the nutritional requirements. The improvement in the production potential of the existing layer population is more imperative as compared to the size of the flock. In this aspect induced moulting is a valuable as well as economical practice especially for the developing countries. There are many methods to induce the moulting which are under investigation to prove the competency over the other. So, there was a need to compile these extensive studies regarding the induced moulting with relation to different aspects. The review of the literature is always the basic necessity to make further hypothesis. In addition to the different moulting programmes the supplementation of the molted birds with protein and probiotics will also be a provoking idea in order to improve the production potential of the molted layers.

Response of green gram [Vigna radiata (L.) Wilczek] to fertilization through soil and foliage - a review

Abstract: Greater emphasis is now laid on increasing the productivity and thereby the total production of pulses in order to mitigate the protein hunger of growing population of our country. Hence, cultivation of high yielding input responsive varieties of green gram is being recommended. In addition to other management practices such as irrigation and plant protection, green gram responds markedly to plant population level and mineral nutrition especially, when applied in balanced amount and by appropriate methods. However, the response of grengram to fertilizer application varies from place to place and variety to variety. Hence, to have an understanding on the works done on so far the literature pertaining to response of greengram to fertilizer application through soil and foliage is reviewed in this article.

RNA interference technology: implications and applications - a review.

Abstract: RNA interference is a phenomenon in which the introduction of double-stranded RNA (dsRNA) into a diverse range of organisms and cell types causes degradation of the complementary mRNA. ShRNA, siRNA and micro RNA are the three types of small interfering RNA involved in the gene silencing mechanism. This mechanism is triggered by double stranded RNA, which is cleaved by endoribonucleases, Drosha and Dicer to produce short RNA (si RNA) duplexes of 21-25 nt in length. The siRNA is further processed such that one of the two strands, (the passenger strand) is destroyed, while the other strand (the guide strand or antisense strand) complexes with multiple proteins to form the RNA- induced silencing complex (RISC). It is the RISC that mediates sequence specific gene silencing by recognizing the m- RNA containing sequences complimentarily with the guide strand of the siRNA. Keeping in view the importance of this highly specific DNA sequence knock down mechanism and the diverse applications of this technology, this review describes the designing of siRNAs, allele specific RNA interference, inhibition of hepatitis B Virus replication by various RNAi constructs, applications in livestock and agricultural species, si RNA therapy, si RNA delivery systems and the challenges associated with it like immune stimulation and offtargeting effect, which should be obliterated in order to enhance the efficiency of this technology.