Development of a compressed FCN architecture for semantic segmentation using Particle Swarm Optimization.

Researchers have adapted the conventional deep learning classification networks to generate Fully Conventional Networks (FCN) for carrying out accurate semantic segmentation. However, such models are expensive both in terms of storage and inference time and not readily employable on edge devices. In this paper, a compressed version of VGG16-based Fully Convolution Network (FCN) has been developed using Particle Swarm Optimization. It has been shown that the developed model can offer tremendous saving in storage space and also faster inference time, and can be implemented on edge devices. The efficacy of the proposed approach has been tested using potato late blight leaf images from publicly available PlantVillage dataset, street scene image dataset and lungs X-Ray dataset and it has been shown that it approaches the accuracies offered by standard FCN even after 851× compression.

Population dynamics of Citrus tristeza virus (CTV) in single aphid-transmitted sub-isolates of the South African GFMS12 isolate.

Grapefruit trees in South Africa have been cross protected against severe stem pitting genotypes of Citrus tristeza virus (CTV) since the 1920s using a mild strain initially called 'Nartia' but later referred to as grapefruit mild strain 12 (GFMS12). In the current study, the GFMS12 isolate was used as the source for single aphid transmissions (SAT) using Toxoptera citricida, commonly called the brown citrus aphid (BrCA). The BrCA-transmitted CTV sub-isolates were analyzed by the heteroduplex mobility assay (HMA), serological assays, genetic marker analysis (GMA), and selected sub-isolates were biologically indexed. Reverse transcription PCR of genomic regions was conducted using universal primers followed by cloning the PCR products, HMA and sequence analysis; nine genotypes of CTV were identified in the complex of GFMS12, including both severe and mild genotypes. A single BrCA transmitted up to six CTV genotypes simultaneously in one sub-isolate. The HMA was found to be a rapid, reliable tool for the identification of genotypes and can be useful in the development of CTV management strategies and budwood certification programs.

Advances in Nanotechnology as a Potential Alternative for Plant Viral Disease Management.

Plant viruses cause enormous losses in agricultural production accounting for about 47% of the total overall crop losses caused by plant pathogens. More than 50% of the emerging plant diseases are reported to be caused by viruses, which are inevitable or unmanageable. Therefore, it is essential to devise novel and effective management strategies to combat the losses caused by the plant virus in economically important crops. Nanotechnology presents a new tendency against the increasing challenges in the diagnosis and management of plant viruses as well as plant health. The application of nanotechnology in plant virology, known as nanophytovirology, includes disease diagnostics, drug delivery, genetic transformation, therapeutants, plant defense induction, and bio-stimulation; however, it is still in the nascent stage. The unique physicochemical properties of particles in the nanoscale allow greater interaction and it may knock out the virus particles. Thus, it opens up a novel arena for the management of plant viral diseases. The main objective of this review is to focus on the mounting collection of tools and techniques involved in the viral disease diagnosis and management and to elucidate their mode of action along with toxicological concerns.

A multiplex polymerase chain reaction for the simultaneous detection of the virus and satellite components associated with cotton leaf curl begomovirus disease complex.

Cotton leaf curl disease (CLCuD) is caused by a complex of several whiteflies (Bemisia tabaci Genn.)-transmitted begomovirus species, Cotton leaf curl Multan virus (CLCuMuV), Cotton leaf curl Kokhran virus (CLCuKoV) and Cotton leaf curl Alabad virus (CLCuAlV) by individual of mixed infection, associated with Cotton leaf curl Multan betasatellite (CLCuMB) and several alphasatellites. The disease causes major economic losses in cotton in the Indian subcontinent. For monitoring of epidemiology and development of management strategies of CLCuD, a quick, sensitive and effective method capable of detecting all the begomovirus, betasatellite and alphasatellite components associated with CLCuD is required. With this objective, a multiplex polymerase chain reaction (mPCR) assay was developed for the simultaneous detection of these three viral components associated with CLCuD of cotton. Primers for each component were designed based on the retrieved reference sequences from the GenBank. Each pair of primers, designed for each of the respective component, was evaluated for its sensitivity and specificity in both the component-specific simplex polymerase chain reaction (sPCR) and mPCR assay. This report identified three viral component-specific pairs of primers which, in all combinations, amplified simultaneously the CP gene (780 nts) of the begomovirus, the ßC1gene (375 nts) of the betasatellite and the Rep gene (452 nts) of the alphasatellite associated with CLCuD in the mPCR assays. The amplified products specific to each component produced by these assays were identified based on their amplicon sizes, and the identities of the viral components amplified were confirmed by cloning and sequencing the amplicons obtained in the mPCR. The mPCR assay was validated using naturally CLCuD-affected cotton plants of the fields. This assay will be useful for rapid detection of CLCuD-associated begomovirus, betasatellite and alphasatellite DNA in field samples, extensive resistance screening in resistance breeding programme, and also monitoring epidemiology for detection of virus and its components when symptoms are mild or absent in the plant.

Distribution, genetic diversity and recombination analysis of Citrus tristeza virus of India.

Citrus tristeza virus (CTV) isolates representing all the citrus-growing geographical zones of India were analyzed for nucleotide sequence of the 5'ORF1a fragments of the partial LProI domain and for the coat protein (CP) gene. The nucleotide sequences were compared with previously reported Indian and CTV genotypes from GenBank. The Indian isolates had 80-99 % sequence identity for the 5'ORF1a and 89-99 % identity for the CP genes. In phylogenetic tree analysis, all the Indian and previously reported isolates segregated into eight clades or groups for the 5'ORF1a region. Indian CTV isolates were clustered in all the clades, four of which, D13, K5, BAN-1, and B165, consisted of only Indian isolates. Phylogenetic tree analysis of the CP genes resulted in seven clades. Indian CTV isolates clustered in six of them, and clades I and VI consisted of only Indian isolates. In the phylogenetic tree the Indian CTV isolates clustered in different groups regardless their geographical origin. Diversities in CTV isolates within individual citrus farms were highlighted. Because incongruent phylogenetic relationships were observed for both of the genomic regions, 5'ORF1a and CP gene, recombination analysis was performed using program RDP3. This analysis detected potential recombination events among the CTV isolates which involved exchange of sequences between divergent CTV variants. The SplitsTree analysis showed evidence of phylogenetic conflicts in evolutionary relationships among CTV isolates.

Molecular characterization of Citrus tristeza virus isolates from the Northeastern Himalayan region of India.

Citrus tristeza virus (CTV) isolates from the Darjeeling hills of the Northeastern Himalayan region of India were characterized by biological indexing, multiple molecular marker (MMM) analysis, heteroduplex mobility assay (HMA) and sequence analysis. Variability was studied using the CP gene and a 5' ORF1a fragment of the CTV genome. HMA and sequence analysis of the 5' ORF1a fragment classified Darjeeling isolates into two groups, whereas CP gene analysis provided evidence for three different groups. Darjeeling CTV isolates shared nucleotide sequence identities of 89-97 and 91-92% in the 5' ORF1a fragment and CP gene, respectively, suggesting extensive diversity among CTV isolates from this Indian region.