Prospects of improving flooding tolerance in lowland rice varieties by conventional breeding and genetic engineering

Flooding is a recurrent phenomenon in several lowland rice-growing areas in India and elsewhere. Even though rice is a reasonably flooding-tolerant crop, the annual loss incurred by farmers due to floods is large. There are excellent traditional rice types with high level flooding tolerance. Combining high level flooding tolerance to high grain yield through conventional breeding has been successful to a limited extent so far but there are enormous opportunities for the same. There are also hopes that flooding tolerance can be genetically engineered in rice using a transgenic approach. We take a look on the prospects for improvement of rice to flooding stress through conventional breeding and through plant genetic engineering

Production of high temperature tolerant transgenic plants through manipulation of membrane lipids

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Adaptive Testing and Performance Analysis Using Naive Bayes Classifier

AbstractThe highlight of this paper is to demonstrate the concept of adaptive tests which are an efficient way to produce the desired result as compared to the traditional static tests. The algorithm learns to adapt to the user's knowledge, and thus, calculates the true ability of the user. Our test system also provides the user with his performance review in specific categories, thereby giving him an understanding of his current knowledge for the same. Thus, our model can improve the user‟s efficacy over a prolonged period of time

Binary cloning vectors for efficient genetic transformation of rice plants

The availability of effective vector systems is a prerequisite for genetic manipulation of plants through recombinant DNA technology. We report here construction of a series of binary vectors that have cauliflower mosaic virus 35S promoter-driven genes encoding either resistance to hygromycin or phosphinothricin for selection of the transformants, and high strength constitutive promoters of either ubiquitin1 or actin1 genes for efficient expression of the transgenes. The efficacy of the constructs is tested in stably transformed Pusa Basmati 1 rice plants through β-glucuronidase reporter gene activity. Availability of vectors with variable promoters and selectable marker genes provides flexibility in stacking two genes. The vectors constructed in this study are suitable for both particle gun and Agrobacterium-based transformation protocols

Identification and characterization of miRNAome in root, stem, leaf and tuber developmental stages of potato (Solanum tuberosum L.) by high-throughput sequencing

BACKGROUND: MicroRNAs (miRNAs) are ubiquitous components of endogenous plant transcriptome. miRNAs are small, single-stranded and ~21 nt long RNAs which regulate gene expression at the post-transcriptional level and are known to play essential roles in various aspects of plant development and growth. Previously, a number of miRNAs have been identified in potato through in silico analysis and deep sequencing approach. However, identification of miRNAs through deep sequencing approach was limited to a few tissue types and developmental stages. This study reports the identification and characterization of potato miRNAs in three different vegetative tissues and four stages of tuber development by high throughput sequencing. RESULTS: Small RNA libraries were constructed from leaf, stem, root and four early developmental stages of tuberization and subjected to deep sequencing, followed by bioinformatics analysis. A total of 89 conserved miRNAs (belonging to 33 families), 147 potato-specific miRNAs (with star sequence) and 112 candidate potato-specific miRNAs (without star sequence) were identified. The digital expression profiling based on TPM (Transcripts Per Million) and qRT-PCR analysis of conserved and potato-specific miRNAs revealed that some of the miRNAs showed tissue specific expression (leaf, stem and root) while a few demonstrated tuberization stage-specific expressions. Targets were predicted for identified conserved and potato-specific miRNAs, and predicted targets of four conserved miRNAs, miR160, miR164, miR172 and miR171, which are ARF16 (Auxin Response Factor 16), NAM (NO APICAL MERISTEM), RAP1 (Relative to APETALA2 1) and HAM (HAIRY MERISTEM) respectively, were experimentally validated using 5′ RLM-RACE (RNA ligase mediated rapid amplification of cDNA ends). Gene ontology (GO) analysis for potato-specific miRNAs was also performed to predict their potential biological functions. CONCLUSIONS: We report a comprehensive study of potato miRNAs at genome-wide level by high-throughput sequencing and demonstrate that these miRNAs have tissue and/or developmental stage-specific expression profile. Also, predicted targets of conserved miRNAs were experimentally confirmed for the first time in potato. Our findings indicate the existence of extensive and complex small RNA population in this crop and suggest their important role in pathways involved in diverse biological processes, including tuber development

Evaluating rice germplasm for iron and zinc concentration in brown rice and seed dimensions

The lack of micronutrients such as Fe and Zn in staple food crops is a widespread nutrition and health problem in developing countries. Biofortification is one of the sustainable approaches, for improving the Fe and Zn content and their bioavailability in rice grain. Screening germplasm for Fe and Zn content is the initial step of biofortification. We analyzed brown rice of 126 accessions of rice genotypes for Fe and Zn concentration. Iron concentration ranged from 6.2 ppm to 71.6 ppm and zinc from 26.2 ppm to 67.3 ppm. Zn concentration and grain elongation (-0.25) was significantly correlated. The wild accessions had the highest Fe and Zn. Thus, wild species are a good source for biofortification of popular rice cultivars using conventional, acceptable, non transgenic methods. Â

Experimentation in biology of plant abiotic stress responses

During the course of growth under natural field conditions, crop plants are exposed to a number of different abiotic stresses (such as water stress, temperature stress, salt stress, flooding stress, chemical stress and oxidative stress). These stresses exert adverse effects on metabolism, growth and yield of the crops. The intensity of the abiotic stresses is on the rise, implying that various possible solutions for mitigating the damage caused by such stresses must be combined for future increase in crop production. At the level of plant genetics, there are indications that it may be possible to improve plants against such stress factors. However, the practical success in this regard depends on how well we understand the biochemistry. physiology and molecular biology of the plant abiotic stress responses. The cellular response of plants to abiotic stresses is of complex nature involving simultaneous interplay of several mechanisms. Although there is a great deal of progress in cataloguing the biochemical reactions that are associated with plant abiotic stress responses, precise understanding of the defense reactions leading to acquisition of stress tolerance remains a challenge. A number of different experimental systems including lower and higher plants as well as microbes have been analyzed for examining the plant abiotic stress responses. The molecular analysis of the stress response has been carried out at the level of stress proteins, stress genes, stress promoters, trans-acting factors that bind to stress promoters and signal transduction components involved in mediation of stress responses. The functional relevance of the stress - associated genes is being tested in different trans-systems including yeast as well as higher plant species. In this article, we discuss selective features of experimentation in biology of plant abiotic stress responses

Japanese Encephalitis Outbreak, India, 2005

An outbreak of viral encephalitis occurred in Gorakhpur, India, from July through November 2005. The etiologic agent was confirmed to be Japanese encephalitis virus by analyzing 326 acute-phase clinical specimens for virus-specific antibodies and viral RNA and by virus isolation. Phylogenetic analysis showed that these isolates belonged to genogroup 3

Pigeonpea

Pigeonpea is one of the major grain legumes grown in the tropics and subtropics of the world that forms a significant component of the diet due to its high protein content. Most of the differences in potential and realized yields in pigeonpea have been attributed to several biotic and abiotic constraints; besides the low productivity potential of marginal lands, where this crop is commonly grown. Of the various constraints limiting pigeonpea production, insect pests cause substantial damages. Conventional breeding efforts in pigeonpea crop improvement have been successful in producing improved seed quality and reduction of crop maturity duration. Nevertheless, genetic improvement of pigeonpea has been restricted due to the nonavailability of better genetic resources and strong sexual barriers between the cultivated and wild species. The recent developments in plant genetic engineering have provided immense potential in overcoming some of these constraints, thereby, offering opportunities for its successful integration with conventional crop improvement strategies. This chapter describes the pigeonpea crop, various constraints to its productivity, recent developments in its breeding, and emerging transgenic innovations that could play a significant role in the improvement of pigeonpea crop. We also highlight the current status of pigeonpea transgenics and related biosafety and IPR issues for the successful application of this technology in the near future

Plant Hsp100 proteins: structure, function and regulation

Hsp100/Clp family of proteins has been characterized to appreciable details in Escherichia coli, Saccharomyces cerevisiae and other such simpler biological species. In plants, yeast Hsp104-related protein was first identified in Oryza sativa. cDNA and genomic DNA clones encoding Hsp100 have been isolated and characterized from several plant species thus far. Detailed amino acid sequence analysis has revealed that Hsp100 members contain several conserved signatures. The signature sequences of various motifs of plant Hsp100 members are redefined by reducing the redundancy in this study. Based on in silico analysis, we find that a nucleotide sequence homologous to Phaseolus lunatus chloroplastic hsp100 is present in Arabidopsis genome. Yeast Hsp104 is implicated in the disaggregation of heat-inactivated proteins, thereby protecting cells during heat shock. Plant Hsp100 proteins have been shown to be functionally analogous to yeast Hsp104 by complementation studies. Hsp100 is proven to be critical for the acquisition of thermotolerance as shown by transgenic and mutation based analyses. There are indications that plant Hsp100 proteins interact and recruit components of translational machinery to specific mRNAs in order to enhance their translation. Studies on Arabidopsis thaliana, O. sativa and Zea mays reveal that besides heat stress, Hsp100 proteins are also developmentally regulated