Publications of NIPGR Scientists
Permanent URI for this communityhttps://ndkr-library.nipgr.ac.in/handle/123456789/1
Browse
6 results
Search Results
Item A comprehensive Vis-NIRS equation for rapid quantification of seed glucosinolate content and composition across diverse Brassica oilseed chemotypes(Elsevier B.V., 2021) Gohain, Bornali; Kumar, Pawan; Malhotra, Bhanu; Augustine, Rehna; Pradhan, Akshay K.; Bisht, Naveen C.The globally cultivated Brassica crops contain high deliverable concentrations of health-promoting glucosinolates. Development of a Visible-Near InfraRed Spectroscopy (Vis-NIRS) calibration to profile different glucosinolate components from 641 diverse Brassica juncea chemotypes was attempted in this study. Principal component analysis of HPLC-determined glucosinolates established the distinctiveness of four B. juncea populations used. Subsequently, modified partial least square regression based population-specific and combined Vis-NIRS models were developed, wherein the combined model exhibited higher coefficient of determination (R2; 0.81–0.97) for eight glucosinolates and higher ratio of prediction determination (RPD; 2.42–5.35) for seven glucosinolates in B. juncea populations. Furthermore, range error ratio (RER > 4) for twelve and RER > 10 for eight glucosinolates make the combined model acceptable for screening and quality control. The model also provided excellent prediction for aliphatic glucosinolates in four oilseed Brassica species. Overall, our work highlights the potential of Vis-NIR spectroscopy in estimating glucosinolate content in the economically important Brassica oilseeds.Item Molecular basis of the evolution of methylthioalkylmalate synthase and diversity of methionine-derived glucosinolates(American Society of Plant Biologists, 2019) Kumar, Roshan; Lee, Soon Goo; Augustine, Rehna; Reichelt, Micheal; Vassão, Daniel G.; Palavalli, Manoj H.; Allen, Aron; Gershenzon, Jonathan; Jez, Joseph M.; Bisht, Naveen C.Methylthioalkylmalate synthase catalyzes the committed step in the side-chain elongation of methionine-derived aliphatic glucosinolates and likely evolved from the isopropylmalate synthases of leucine biosynthesis. The globally cultivated Brassica species possess diverse aliphatic glucosinolates important for plant defense and animal nutrition; however, the molecular basis for the evolution of methylthioalkylmalate synthase and its generation of natural product diversity in Brassica is poorly understood. Here we show that Brassica genomes encode multiple methylthioalkylmalate synthase that have differences in expression profiles and 2-oxo substrate preference that account for diversity of aliphatic glucosinolates across Brassica accessions. The 2.1 Å resolution x-ray crystal structure of B. juncea methylthioalkylmalate synthase identifies key active site residues responsible for controlling specificity for different 2-oxo substrates and the determinants of side-chain length in aliphatic glucosinolates. Overall, these results provide the evolutionary and biochemical foundation for diversification of glucosinolates profiles across globally-cultivated Brassica species, which could be used with ongoing breeding strategies towards manipulation of beneficial glucosinolates compounds for animal health and plant protection.Item Targeted silencing of genes in polyploids: lessons learned from Brassica juncea-glucosinolate system(Springer Nature, 2019) Augustine, Rehna; Bisht, Naveen C.Key message Intron-spliced hairpin RNAi construct targeting the exonic region of BjuMYB28 driven by the native promoter is the best suited strategy for developing viable low glucosinolate lines in polyploid Brassica juncea. Abstract Targeted silencing of specific homolog(s) of a multigene family in polyploids through RNA interference (RNAi) is a challenging effort. Indian oilseed mustard (Brassica juncea), a natural allotetraploid, is expected to have 4–6 copies of every Arabidopsis gene ortholog. In the current study, we have attempted to establish the best gene silencing system suitable for BjuMYB28, a transcription factor gene, with the objective of developing low seed glucosinolate lines in B. juncea. After comparing multiple combinations of BjuMYB28 gene homologs, promoters, target regions (exon and 3′ UTR) and silencing strategies (RNAi and antisense), we suggest that the intron-spliced hairpin RNAi construct targeting the specific exonic region of the BjuMYB28 gene under the control of native promoter, whose peak activity synchronises with the highest glucosinolate accumulation phase of the plant, is the best suited strategy for developing viable low glucosinolate lines in polyploid B. juncea.Item Regulation of glucosinolate metabolism: From model plant Arabidopsis thaliana to Brassica crops(Springer, 2017) Augustine, Rehna; Bisht, Naveen C.Brassicaceae are blessed with secondary metabolites called glucosinolates which form the defense arsenal of these plants. Glucosinolates and its degradation products are also proved to be beneficial in agriculture and human health even though some are known to be detrimental. The type of glucosinolates and its content displays huge diversity across different species. The glucosinolate diversity is primarily genetically controlled. The profile of glucosinolates also varies depending on the growth stages and external environment of the plant. The environmental factors include type of pest/pathogen attack, nutrient status of the plant, and other abiotic stress factors. The glucosinolate pathway is also linked to other major metabolic and signaling pathways resulting in a complex mechanism of regulation. Even though the regulatory mechanism is not completely understood, the current chapter integrates the knowledge available from the model plant Arabidopsis and related Brassica crops.Item Biotic elicitors and mechanical damage modulate glucosinolate accumulation by co-ordinated interplay of glucosinolate biosynthesis regulators in polyploid Brassica juncea(Elsevier B.V., 2015) Augustine, Rehna; Bisht, Naveen C.Glucosinolates are nitrogen and sulfur containing secondary metabolites found mainly in the Brassicaceae. They function as plant defense compounds against a broad spectrum of pathogens and pests. Since these molecules form part of the plant defense mechanism, glucosinolate biosynthesis may be modulated by environmental signals leading to activation of a biological stress response. In the current study, we have mimicked such conditions by exogenously applying biotic elicitors such as methyl jasmonate, salicylic acid, glucose and mechanical injury in Brassica juncea seedling over a time course experiment. We found that total glucosinolates over-accumulated under these stress conditions with maximum accumulation observed 24h post treatment. Indole glucosinolates like 1-methoxy-indol-3-ylmethyl and its precursor indol-3-methyl glucosinolates showed a more significant induction compared to aliphatic glucosinolates thereby suggesting a prominent role of indole glucosinolates during plant defense response in B. juncea seedlings. In contrast, the higher amounts of aliphatic glucosinolates were less regulated by the tested biotic elicitors in B. juncea. Expression profiling of multiple homologs of key transcriptional regulators of glucosinolate biosynthesis further showed that a complex interplay of these regulators exists in polyploid B. juncea where they exert co-ordinated and overlapping effects toward altering glucosinolate accumulation. This study has a significant role toward understanding and augmenting plant defense mechanisms in B. juncea, a globally important oilseed crop of genus Brassica.Item Translational genomics in Brassica crops: challenges, progress, and future prospects(Springer, 2014) Augustine, Rehna; Arya, Gulab C.; Nambiar, Deepti M.; Kumar, Roshan; Bisht, Naveen C.The last two decades have been a period of rapid advancement in our understanding of plant biology and its related developmental processes. This advancement has been facilitated by the adoption of plant models for most of the economically important plant families, as well as the development of enriched genetic, genomic, transcriptomic and metabolomic resources. In recent years, sequencing projects on major crops have further enhanced our understanding of their genomic structure, evolution, gene functions, and, most importantly, this knowledge has been utilized for crop improvement. The Brassicaceae family contains several important research and agricultural species, including the model plant Arabidopsis thaliana and economically important Brassica crops that are of great importance to human health and agriculture. Exploiting heterosis for yield enhancement, increasing tolerance against biotic and abiotic factors, and improving nutritional value remain the priorities in Brassica crop improvement. This review summarizes the potential of recently adopted genetic and genomic resources, as well as the basic knowledge obtained from studying the closest model plant A. thaliana, to accelerate the crop improvement programs in Brassica crops.