Evidence of salicylic acid pathway with EDS1 and PAD4 proteins by molecular dynamics simulation for grape improvement

Biotic stress is a major cause of heavy loss in grape productivity. In order to develop biotic stress-resistant grape varieties, the key defense genes along with its pathway have to be deciphered. In angiosperm plants, lipase-like protein phytoalexin deficient 4 (PAD4) is well known to be essential for systemic resistance against biotic stress. PAD4 functions together with its interacting partner protein enhanced disease susceptibility 1 (EDS1) to promote salicylic acid (SA)-dependent and SA-independent defense pathway. Existence and structure of key protein of systemic resistance EDS1 and PAD4 are not known in grapes. Before SA pathway studies are taken in grape, molecular evidence of EDS1: PAD4 complex is to be established. To establish this, EDS1 protein sequence was retrieved from NCBI and homologous PAD4 protein was generated using Arabidopsis thaliana as template and conserved domains were confirmed. In this study, computational methods were used to model EDS1 and PAD4 and simulated the interactions of EDS1 and PAD4. Since no structural details of the proteins were available, homology modeling was employed to construct three-dimensional structures. Further, molecular dynamic simulations were performed to study the dynamic behavior of the EDS1 and PAD4. The modeled proteins were validated and subjected to molecular docking analysis. Molecular evidence of stable complex of EDS1:PAD4 in grape supporting SA defense pathway in response to biotic stress is reported in this study. If SA defense pathway genes are explored, then markers of genes involved can play pivotal role in grape variety development especially against biotic stress leading to higher productivity.     

Biotic stress resistance in agriculture through antimicrobial peptides

Antimicrobial peptides (AMPs) are the hosts' defense molecules against microbial pathogens and gaining extensive research attention worldwide. These have been reported to play vital role of host innate immunity in response to microbial challenges. AMPs can be used as a natural antibiotic as an alternative of their chemical counterpart for protection of plants/animals against diseases. There are a number of sources of AMPs including prokaryotic and eukaryotic organisms and are present, both in vertebrates and invertebrates. AMPs can be classified as cationic or anionic, based on net charges. Large number of databases and tools are available in the public domain which can be used for development of new genetically modified disease resistant varieties/breeds for agricultural production. The results of the biotechnological research as well as genetic engineering related to AMPs have shown high potential for reduction of economic losses of agricultural produce due to pathogens. In this article, an attempt has been made to introduce the role of AMPs in relation to plants and animals. Their functional and structural characteristics have been described in terms of its role in agriculture. Different sources of AMPs and importance of these sources has been reviewed in terms of its availability. This article also reviews the bioinformatics resources including different database tools and algorithms available in public domain. References of promising biotechnology research in relation to AMPs, prospects of AMPs for further development of genetically modified varieties/breeds are highlighted. AMPs are valuable resource for students, researchers, educators and medical and industrial personnel.     

Genomic analysis of polycarpellary rice (Oryza sativa L.) through whole genome resequencing

There is a natural floral organ mutant of rice (var. Jugal) where the florets, popularly known as spikelet bear multiple carpels and produce multiple kernels in most of its grain. In our earlier work a detailed study has been done on its morpho-anatomical structure with allelic diversity and expression study of the major genetic loci associated with floral organ development. In present study high throughput whole genome sequencing was done which generated about of 3.7 million base pair genomic data for downstream analysis. The reads were about 101 bases long and mapped to the Oryza sativa var. Nipponbare as reference genome. Genome wide variant analysis detected 1,096,419 variants which included 943,033 SNPs and 153,386 InDels. A total of 24,920 non-synonymous SNPs were identified for 11,529 identified genes. Chromosome-wise distribution of uniquely mapped reads onto reference genome showed that maximum reads were mapped to 1st chromosome and least to 9th chromosome. 10th chromosome showed highest density of variations (about 325.6 per 100 kb genome sequence). Detailed sequence analysis of 23 floral organ developmental genes detected 419 potent variants where DL (Drooping Leaf) and OSH1 (Oryza sativa Homeobox1) genes showed highest number (32) of variants; whereas, MADS21 (Minichromosome Agamous Deficient Serum Factor 21) gene have lowest number (5) of variants. The information generated in this study will enrich the genomics of floral organ development in indica rice and cereal crops in general.

     

Characterization of genetic diversity and population structure in wheat using array based SNP markers

Genetic diversity is crucial for successful adaptation and sustained improvement in crops. India is bestowed with diverse agro-climatic conditions which makes it rich in wheat germplasm adapted to various niches. Germplasm repository consists of local landraces, trait specific genetic stocks including introgressions from wild relatives, exotic collections, released varieties, and improved germplasm. Characterization of genetic diversity is done using morpho-physiological characters as well as by analyzing variations at DNA level. However, there are not many reports on array based high throughput SNP markers having characteristics of genome wide coverage employed in Indian spring wheat germplasm. Amongst wheat SNP arrays, 35K Axiom Wheat Breeder’s Array has the highest SNP polymorphism efficiency suitable for genetic mapping and genetic diversity characterization. Therefore, genotyping was done using 35K in 483 wheat genotypes resulting in 14,650 quality filtered SNPs, that were distributed across the B (~?50%), A (~?39%), and D (~?10%) genomes. The total genetic distance coverage was 4477.85 cM with 3.27 SNP/cM and 0.49 cM/SNP as average marker density and average inter-marker distance, respectively. The PIC ranged from 0.09 to 0.38 with an average of 0.29 across genomes. Population structure and Principal Coordinate Analysis resulted in two subpopulations (SP1 and SP2). The analysis of molecular variance revealed the genetic variation of 2% among and 98% within subpopulations indicating high gene flow between SP1 and SP2. The subpopulation SP2 showed high level of genetic diversity based on genetic diversity indices viz. Shannon’s information index (I)?=?0.648, expected heterozygosity (He)?=?0.456 and unbiased expected heterozygosity (uHe)?=?0.456. To the best of our knowledge, this study is the first to include the largest set of Indian wheat genotypes studied exclusively for genetic diversity. These findings may serve as a potential source for the identification of uncharacterized QTL/gene using genome wide association studies and marker assisted selection in wheat breeding programs.

     

Development of Antimicrobial Peptide Prediction Tool for Aquaculture Industries

Microbial diseases in fish, plant, animal and human are rising constantly; thus, discovery of their antidote is imperative. The use of antibiotic in aquaculture further compounds the problem by development of resistance and consequent consumer health risk by bio-magnification. Antimicrobial peptides (AMPs) have been highly promising as natural alternative to chemical antibiotics. Though AMPs are molecules of innate immune defense of all advance eukaryotic organisms, fish being heavily dependent on their innate immune defense has been a good source of AMPs with much wider applicability. Machine learning-based prediction method using wet laboratory-validated fish AMP can accelerate the AMP discovery using available fish genomic and proteomic data. Earlier AMP prediction servers are based on multi-phyla/species data, and we report here the world’s first AMP prediction server in fishes. It is freely accessible at http://webapp.cabgrid.res.in/fishamp/. A total of 151 AMPs related to fish collected from various databases and published literature were taken for this study. For model development and prediction, N-terminus residues, C-terminus residues and full sequences were considered. Best models were with kernels polynomial-2, linear and radial basis function with accuracy of 97, 99 and 97 %, respectively. We found that performance of support vector machine-based models is superior to artificial neural network. This in silico approach can drastically reduce the time and cost of AMP discovery. This accelerated discovery of lead AMP molecules having potential wider applications in diverse area like fish and human health as substitute of antibiotics, immunomodulator, antitumor, vaccine adjuvant and inactivator, and also for packaged food can be of much importance for industries.     

Correction to: Understanding population structure and detection of QTLs for curding related traits in Indian cauliflower by genotyping by sequencing analysis

Functional & Integrative Genomics -     

Seasonal parasitism and biological characteristics of Habrobracon hebetor (Hymenoptera: Braconidae) – a potential larval ectoparasitoid of Helicoverpa armigera (Lepidoptera: Noctuidae) in a chickpea ecosystem

Seasonal parasitism of Habrobracon hebetor (Say) on Helicoverpa armigera (Hübner) in chickpea was studied for three consecutive years. Parasitism by H. hebetor on larvae of H. armigera reached 12.3%. The parasitoid maintained reproductive activity on H. armigera from February to April coinciding with pod formation and maturation stages of the crop. In laboratory assays, we investigated the suitability of larval instars of H. armigera to the parasitoid H. hebetor. This parasitoid attacked third to sixth instars, though fourth and fifth instar larvae were found most suitable with 100% parasitism and development to adults. Parasitoid developmental time was longest in fifth instar (9.1 days) compared to other instars (8.1–8.9 days). Fifth instar larvae resulted in highest numbers of cocoons and adult emergence. In addition, suitability of seven lepidopteran species to H. hebetor was investigated. Corcyra cephalonica, Galleria mellonella and H. armigera were the most suitable hosts with 100% parasitism and development to adults. It was followed by Maruca vitrata and Autographa nigrisigna with 60–76.7% and 40–70% parasitism and parasitoid developmental success, respectively. Though there was 23.3% parasitism, there was no parasitoid development in Spodoptera litura. No parasitism was recorded in Spilarctia obliqua. Development of H. hebetor was most rapid in C. cephalonica (8.7 days), and longest in G. mellonella (9.3 days). Parasitoids that developed on these hosts resulted in highest numbers of cocoons and adult emergence. The parasitoid could be exploited for the biological control of H. armigera in a chickpea ecosystem.     

Understanding population structure and detection of QTLs for curding-related traits in Indian cauliflower by genotyping by sequencing analysis

Functional & Integrative Genomics - Curd initiation and development are complex traits and highly responsive for different temperature ranges in cauliflower. The present study was aimed to...