Genome-wide SNP discovery and genotyping delineates potential QTLs underlying major yield-attributing traits in buckwheat.

Buckwheat (Fagopyrum spp.) is an important nutritional and nutraceutical-rich pseudo-cereal crop. Despite its obvious potential as a functional food, buckwheat has not been fully harnessed due to its low yield, self-incompatibility, increased seed cracking, limited seed set, lodging, and frost susceptibility. The inadequate availability of genomics resources in buckwheat is one of the major reasons for this. In the present study, genome-wide association mapping (GWAS) was conducted to identify loci associated with various morphological and yield-related traits in buckwheat. High throughput genotyping by sequencing led to the identification of 34,978 single nucleotide polymorphisms that were distributed across eight chromosomes. Population structure analysis grouped the genotypes into three sub-populations. The genotypes were also characterized for various qualitative and quantitative traits at two diverse locations, the analysis of which revealed a significant difference in the mean values. The association analysis revealed a total of 71 significant marker-trait associations across eight chromosomes. The candidate genes were identified near 100 Kb of quantitative trait loci (QTLs), providing insights into several metabolic and biosynthetic pathways. The integration of phenology and GWAS in the present study is useful to uncover the consistent genomic regions, related markers associated with various yield-related traits, and potential candidate genes having implications for being utilized in molecular breeding for the improvement of economically important traits in buckwheat. Moreover, the identified QTLs will assist in tracking the desirable alleles of target genes within the buckwheat breeding populations/germplasm.

Explicating genetic architecture governing nutritional quality in pigmented rice.

Rice is one of the most important staple plant foods that provide a major source of calories and nutrients for tackling the global hunger index especially in developing countries. In terms of nutritional profile, pigmented rice grains are favoured for their nutritional and health benefits. The pigmented rice varieties are rich sources of flavonoids, anthocyanin and proanthocyanidin that can be readily incorporated into diets to help address various lifestyle diseases. However, the cultivation of pigmented rice is limited due to low productivity and unfavourable cooking qualities. With the advances in genome sequencing, molecular breeding, gene expression analysis and multi-omics approaches, various attempts have been made to explore the genetic architecture of rice grain pigmentation. In this review, we have compiled the current state of knowledge of the genetic architecture and nutritional value of pigmentation in rice based upon the available experimental evidence. Future research areas that can help to deepen our understanding and help in harnessing the economic and health benefits of pigmented rice are also explored.

Metabolic-GWAS provides insights into genetic architecture of seed metabolome in buckwheat.

BACKGROUND: Buckwheat (Fagopyrum spp.), belonging to the Polygonaceae family, is an ancient pseudo-cereal with high nutritional and nutraceutical properties. Buckwheat proteins are gluten-free and show balanced amino acid and micronutrient profiles, with higher content of health-promoting bioactive flavonoids that make it a golden crop of the future. Plant metabolome is increasingly gaining importance as a crucial component to understand the connection between plant physiology and environment and as a potential link between the genome and phenome. However, the genetic architecture governing the metabolome and thus, the phenome is not well understood. Here, we aim to obtain a deeper insight into the genetic architecture of seed metabolome in buckwheat by integrating high throughput metabolomics and genotyping-by-sequencing applying an array of bioinformatics tools for data analysis. RESULTS: High throughput metabolomic analysis identified 24 metabolites in seed endosperm of 130 diverse buckwheat genotypes. The genotyping-by-sequencing (GBS) of these genotypes revealed 3,728,028 SNPs. The Genome Association and Prediction Integrated Tool (GAPIT) assisted in the identification of 27 SNPs/QTLs linked to 18 metabolites. Candidate genes were identified near 100 Kb of QTLs, providing insights into several metabolic and biosynthetic pathways. CONCLUSIONS: We established the metabolome inventory of 130 germplasm lines of buckwheat, identified QTLs through marker trait association and positions of potential candidate genes. This will pave the way for future dissection of complex economic traits in buckwheat.

Elucidating the process of SNPs identification in non-reference genome crops.

Advances in the next generation sequencing technologies, genome reduction techniques and bioinformatics tools have given a big impetus to the identification of genome-wide single nucleotide polymorphisms (SNPs) in crops. NGS technologies can make available a large amount of sequence data in a short span of time. The huge data requires detailed bioinformatics analysis steps, including preprocessing, mapping, and identification of sequence variants. A plethora of available software meant for sequence analysis is used for different sequence analysis steps. However, SNPs identification is far more challenging for orphaned crops or non-reference genome crops. The current article reports different steps for in silico SNPs identification in a sequential manner and proposes some mapping approaches using CLC Genomics software that could provide an alternative method for SNPs identification in orphan crops having no reference genome. The three mapping approaches: Common reference map from progenitor genomes (CRMPG), step-wise use of progenitor genomes (SWPG) and de novo assembly of sequence read (DASR) were validated with the dd-RAD sequenced data of two genotypes from Brassica juncea.Communicated by Ramaswamy H. Sarma.

Insight Into Microbes and Plants Ability for Bioremediation of Heavy Metals.

Contamination of ground and surface water, soil, and air by harmful and carcinogenic chemicals is one of the most prevalent problems in the modern industrialized world. Heavy metal toxicity has demonstrated to be paramount hazardous and there are various risks associated with it. In addition, these heavy metals have adverse effects on human health and plant physiology. The field of bioremediation has undergone an impactful revolution in recent years due to an exponential increase in various issues related to soil and water pollution. Bioremediation is an advanced and efficient technology, which involves the use of biological means such as microorganisms and plants to degrade heavy metal contaminants. Among the millions of microbes present in the ecosystem, the highest metal adsorption ability is possessed by species belonging to genus Penicillium, Streptomyces, Bacillus, Rhizopus, Chlorella, Ascophyllum, Sargassum, and Aspergillus. Among different plant species, Allium, Eucalyptus, Helianthus, and Hibiscus are the main heavy metal absorbers. The present review concentrates on the research in the bioremediation of important heavy metals through the use of plants and microbes.

C-terminally encoded peptides (CEPs) are potential mediators of abiotic stress response in plants.

Intracellular signaling is a critical determinant of the normal growth and development of plants. Signaling peptides, also known as peptide hormones, along with classical phytohormones, are the significant players of plant intracellular signaling. C-terminally encoded peptide (CEP), a 15-amino acid post-translationally peptide identified in Arabidopsis, plays a pivotal role in lateral root formation, nodulation, and act as long-distance root to shoot signaling molecule in N-starvation conditions. Expression of CEP gene members in Arabidopsis is perturbed by nitrogen starvation; however, not much is known regarding their role in other abiotic stress conditions. To gain a comprehensive insight into CEP biology, we identified CEP genes across diverse plant genera (Glycine max, Sorghum bicolor, Brassica rapa, Zea mays, and Oryza sativa) using bioinformatics tools. In silico promoter analysis revealed that CEP gene promoters show an abundance of abiotic stress-responsive elements suggesting a possible role of CEPs in abiotic stress signaling. Spatial and temporal expression patterns of CEP via RNA seq and microarray revealed that various CEP genes are transcriptionally regulated in response to abiotic stresses. Validation of rice CEP genes expression by qRT-PCR showed that OsCEP1, OsCEP8, OsCEP9, and OsCEP10 were highly upregulated in response to different abiotic stress conditions. Our findings suggest these CEP genes might be important mediators of the abiotic stress response and warrant further overexpression/knockout studies to delineate their precise role in abiotic stress response.

Elucidating micro RNAs role in different plant-pathogen interactions.

Bacteria, fungi, virus and nematode constitute the primary class of pathogens causing plant diseases. Plant-pathogen interactions are crucial for the identification of the host and pathogen and further establishments of a network of interaction that can cross regulate the gene expressions in both sides. After infection, the correct identification of pathogen through various molecular interactions elicit a defense response against the pathogen by alteration of gene expression by the host. Co-evolution of pathogen gives them the ability to counter the virulence response of the host and pathogen can also modulate the host gene expression pattern to make it more susceptible to the infection. Small non-coding RNA molecules (siRNAs and miRNAs) efficiently modulate gene expression at the transcriptional and post-transcriptional level and play a vital role in host defense. The pathogen can also use this double-sided sward in their defense by deregulating the plant immunity via transcriptional control of plant genes utilizing RNA interference or suppressing the host RNA interference response with the help of various RNA silencing suppressor proteins. This mini-review focused on the miRNAs involvement in host defense and how different families of these non-coding regulatory RNAs regulate the defense response against the pathogen.

ddRAD sequencing-based identification of inter-genepool SNPs and association analysis in Brassica juncea.

BACKGROUND: Narrow genetic base, complex allo-tetraploid genome and presence of repetitive elements have led the discovery of single nucleotide polymorphisms (SNPs) in Brassica juncea (AABB; 2n = 4x = 36) at a slower pace. Double digest RAD (ddRAD) - a genome complexity reduction technique followed by NGS was used to generate a total of 23 million paired-end reads from three genotypes each of Indian (Pusa Tarak, RSPR-01 and Urvashi) and Exotic (Donskaja IV, Zem 1 and EC287711) genepools. RESULTS: Sequence data analysis led to the identification of 10,399 SNPs in six genotypes at a read depth of 10x coverage among the genotypes of two genepools. A total of 44 hyper-variable regions (nucleotide variation hotspots) were also found in the genome, of which 93% were found to be a part of coding genes/regions. The functionality of the identified SNPs was estimated by genotyping a subset of SNPs on MassARRAY® platform among a diverse set of B. juncea genotypes. SNP genotyping-based genetic diversity and population studies placed the genotypes into two distinct clusters based mostly on the place of origin. The genotypes were also characterized for six morphological traits, analysis of which revealed a significant difference in the mean values between Indian and Exotic genepools for six traits. The association analysis for six traits identified a total of 45 significant marker-trait associations on 11 chromosomes of A- and B- group of progenitor genomes. CONCLUSIONS: Despite narrow diversity, the ddRAD sequencing was able to identify large number of nucleotide polymorphisms between the two genepools. Association analysis led to the identification of common SNPs/genomic regions associated between flowering and maturity traits, thereby underscoring the possible role of common chromosomal regions-harboring genes controlling flowering and maturity in Brassica juncea.

Plant epigenetic mechanisms: role in abiotic stress and their generational heritability.

Plants have evolved various defense mechanisms including morphological adaptations, cellular pathways, specific signalling molecules and inherent immunity to endure various abiotic stresses during different growth stages. Most of the defense mechanisms are controlled by stress-responsive genes by transcribing and translating specific genes. However, certain modifications of DNA and chromatin along with small RNA-based mechanisms have also been reported to regulate the expression of stress-responsive genes and constitute another line of defense for plants in their struggle against stresses. More recently, studies have suggested that these modifications are heritable to the future generations as well, thereby indicating their possible role in the evolutionary mechanisms related to abiotic stresses.

Oxidative stress induced expression of monodehydroascorbate reductase gene in Eleusine coracana.

Abiotic stresses constitute a serious threats to the world food security as they cause significant economic losses in terms of reduction in crop productivity and also greatly limit the geographical locations where crops can be grown. Exposure to abiotic stress causes over-production of reactive oxygen species, leading to oxidative stress in plants. Induction of oxidative stress is primarily responsible for a variety of detrimental changes in the cellular physiology. However, plants have evolved intricate anti-oxidative defence machinery, for their survival under stress. Plant defence strategies for stress tolerance rely on the expression of anti-oxidative genes required for scavenging the toxic reactive oxygen species. Monodehydroascorbate reductase is one of the key anti-oxidant enzyme responsible for scavenging reactive oxygen species. In the present study, efforts have been made to understand the role of monodehydroascorbate reductase in finger millet under different abiotic stresses (drought, salt and UV radiation). The study establishes a differential link between mdar gene expression and enzyme activity under oxidative stress that is validated under different types of imposed stresses. Alteration in correlation between gene expression and enzyme activities under varying magnitude of oxidative stress is elucidated.