Development of Normalized Cdna Library from Fusarium Wilt Infected Roots of a Tolerant Banana Genotype 'Calcutta-4' Musa acuminata ssp. burmannicoides

Management of the most devasting disease, Fusarium wilt of banana, caused by the fungus Fusarium oxysporum f. sp., cubense, is a challenge to the plant pathologist and the banana grower. Currently, genomics is providing the way for understanding plant defense mechanism, having acquired an important place in crop improvement. To identify the relevant genes and to understand the defense mechanism induced during Fusarium wilt infection, a normalized cDNA library was constructed from infected root samples of a tolerant banana genotype, Musa acuminata spp. burmannicoides 'Calcutta-4', by duplex specific nuclease (DSN) based normalization, using the SMART (switching mechanism at 5' end of RNA transcript) full-length cDNA construction method. Sequencing and analysis of 600 clones revealed 392 non-redundant clones. In all, of 88% of the sequences were annotated using Musa genome database, and the remaining 12% were identified as novel loci not annotated. We observed several resistance genes, ROS scavenging genes and genes involved in ubiquitin-proteosome pathway in this study. These genes may have a possible role against Foc infection. These sequences would enrich the EST data developed against specific stress, which is an indispensable tool for predicting functional genes and understanding the defense mechanism

Duplex Stainless Steels: Effect of Reversion Heat Treatment

Duplex stainless steels present good corrosion resistant and mechanical properties hence they are being used in various pressure boundary components of nuclear power plants such as primary coolant pipes, valves and pump bodies because of the presence of the dual microstructure which consists of equal amounts of austenite and α-ferrite phases. The ratio of austenite and α-ferrite phases mainly depends on the chemical composition. However, when DSS are subjected to the service temperature range of about 300–500°C they undergo embrittlement due to spinodal decomposition of highly alloyed ferrite matrix into iron rich (α) phase and chromium rich (α′) phase. The embrittlement significantly affects impact toughness, tensile strength, ductility, fracture toughness and fatigue behavior limiting the industrial applicability of this steel to temperatures below 280°C. In this chapter, the basic overview of duplex stainless steels and the effect of reversion heat treatment on the thermally embrittled duplex steel is discussed

Spin Decoherence from Hamiltonian dynamics in Quantum Dots

The dynamics of a spin-1/2 particle coupled to a nuclear spin bath through an isotropic Heisenberg interaction is studied, as a model for the spin decoherence in quantum dots. The time-dependent polarization of the central spin is calculated as a function of the bath-spin distribution and the polarizations of the initial bath state. For short times, the polarization of the central spin shows a gaussian decay, and at later times it revives displaying nonmonotonic time dependence. The decoherence time scale dep ends on moments of the bath-spin distribuition, and also on the polarization strengths in various bath-spin channels. The bath polarizations have a tendency to increase the decoherence time scale. The effective dynamics of the central spin polarization is shown to be describ ed by a master equation with non-markovian features.Comment: 11 pages, 6 figures Accepted for publication in Phys.Rev

War of hormones over resource allocation to seeds: strategies and counter-strategies of offspring and maternal parent

It is suggested that maternal parent and offspring have conflicting interests over the extent of resource allocation to developing seeds. While maternal parent would be selected to allocate her resources optimally among her offspring, the latter would be selected to demand more. In animals, offspring are known to demand additional resources either visibly (through intense vocal calls) or subtly through the production of hormones. In plants though parent offspring conflict over resource allocation has been invoked, the mechanism through which the parent and offspring interact in regulating resource allocation into developing seeds is not yet clear. In this paper, we propose that the strategies and counter-strategies of the offspring and mother during the development of seeds might be manifested through the production of appropriate growth hormones. Accordingly, we predict (i) hormones that mobilize resources into seeds (e.g. auxins and gibberellic acid) shall be synthesized exclusively by the offspring tissue and (ii) hormones that inhibit resource flow in to seeds (e.g. abscisic acid) be produced exclusively by the maternal tissue. We show that these predictions are supported by existing literature on the temporal dynamics and source of production of growth hormones during seed development. Finally, we suggest that such analysis viewing the production of different hormones during early seed development, as strategies and counter-strategies of mother and offspring tissue, helps ofer a meaningful interpretation of the otherwise complex dynamics of hormone fluxes

Mango Breeding in India - Past and Future

The mango (Mangifera indica L.) is one of the most important tropical fruits of India in which improvement has been attempted since the early 20th Century. The species, M. indica, having originated in India, has a large diversity within the country. Extensive surveys have located several wild species of importance, many of them figuring in the IUCN Red List. Conservation and evaluation of these species, as well as the large seedling diversity, needs attention as these could be a source for important traits. Strategies of in situ, ex situ and 'onfarm' conservation should from a priority at this juncture. Hybridization has resulted in several hybrids. Widening of genetic base in polyembryonic varieties and identification of zygotic embryos through markers is the need of the hour for utilization in breeding programmes. Although several of these have not become popular, they can be very well used as pre-breeding lines. Use of molecular markers for selection will greatly reduce time taken for developing improved varieties. Strategies other than hybridization, viz., selection among open-pollinated progenies, should be adopted for identifying better recombinants, as, a large number of progenies are available in this method

Marker-Trait Association for Fruit Characters in Mango (Mangifera indica L.) Cultivars

In the present study, putative marker-trait associations were identified within a core collection of mango cultivars by simple-sequence-repeat marker based association study. A panel of 48 mango varieties which represented the core collection of the South-West region of India, were characterized at the molecular level using 31 simple sequence repeat markers. Morphological characterization included important fruit characteristics viz., fruit weight, total soluble solids (TSS), pulp content and acidity. The study on population structure revealed two sub-groups in the core collection. Association analysis, computed by General Linear Model (GLM), using TASSEL resulted in the identification of seven markers being associated with the trait titrable acidity where as one marker each of the traits fruit weight and TSS. These traitspecific markers were highly significant at p<0.05 and explained a good amount of phenotypic variation by exhibiting substantial R2 values ranging from 0.71 to 0.86 for acidity, 0.61 for TSS and 0.59 for fruit weight. This is the first report on marker-trait associations (MTA) in mango

Mining of miRNAs using Next Generation Sequencing (NGS) data generated for Okra (Abelmoschus esculentus)

MicroRNAs (miRNAs) are small, highly conserved non-coding RNA molecules involved in theregulation of gene expression in eukaryotes. Gene expression involves post-transcriptionalgene regulation by miRNAs. miRNAs are formed from precursor RNA molecules that fold intoa stem loop secondary structure. The mature miRNA is one end of the precursor miRNA,defined by the cut from ‘Drosha’ on either the 5’ or 3’ arm. In this study, we have used abioinformatics approach to identify miRNAs in 3,361 contigs obtained from partial genomesequence data of Abelmoschus esculentus (okra) sequenced by NGS technology. Using C-miiand psRNA Target tools, we identified two miRNAs and their target RNAs for which a regulatorymiRNA binding has been verified. Their targets consisted of transcription factors involved ingrowth and development, gene regulation and metabolism. Phylogenetic analysis of the newlyidentified miRNA family has been done to compare their level of conservation with respect tothe other members of the plant kingdom

Genome wide analysis of heat responsive microRNAs in banana during acquired thermo tolerance

MicroRNAs are a class of small regulatory RNAs in plants, which play vital roles during various abiotic and abiotic stress conditions including plant processes. In this present study, we examined the expression of miRNAs and their predicted target expression levels during heat stress in banana. Out of 235 miRNA found in Musa, 40 miRNA showed homology to heat responsive miRNAs from other plants. Further, 14 targets for miRNA were predicted that are potentially regulated by their cognate miRNAs and were monitored under three stages of stress viz, induction, induction + lethal alone using qPCR analysis. The results suggest that generally, there is a negative relationship in the expression patterns of miRNA and their predicted cognate targets - HSP70, HSP90, SAP, DNAj genes. These were highly up regulated and their respective miRNAs showed lower expression. This is the first report in banana, which demonstrated that during induction stress, various thermo-protective genes are activated at initial stages of stress to achieve thermotolerance through altered miRNA expression. The results will help in broadening our understanding acquired thermotolerance and their regulation by miRNAs in plants

Hot QCD equations of state and RHIC

We show how hot QCD equations of states can be adapted to make definite predictions for quark-gluon plasma at RHIC. We consider equations of state up to $O(g^5)$ and $O[g^6(ln(1/g)+\delta)]$. Our method involves the extraction of equilibrium distribution functions for gluons and quarks from these equations of state by capturing the the interaction effects entirely in the effective chemical potentials. We further utilize these distribution functions to study the screening length in hot QCD and dissociation phenomenon of heavy quarkonia states by combining this understanding with the semi-classical transport theory.Comment: Based on poster presented during quark matter-2008(4-10 Feb 2008) Jaipur India; 4 Pages, 2 eps fig