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Main conclusion: Association analysis identified 77 marker–trait associations (MTAs) for PUE traits, of which 10 were high-confidence MTAs. Candidate-gene mining and in-silico expression analysis identified 13 putative candidate genes for PUE traits. Bread wheat (Triticum aestivum L.) is a major cereal crop affected by phosphorus (P) deficiency, which affects root characteristics, plant biomass, and other attributes related to P-use efficiency (PUE). Understanding the genetic mechanisms of PUE traits helps in developing bread wheat cultivars that perform well in low-P environments. With this objective, we evaluated a bread wheat panel comprising 304 accessions for 14 PUE traits with high-throughput phenotyping under low-P and optimum-P treatments and observed a significant genetic variation among germplasm lines for studied traits. Genome-wide association study (GWAS) using 14,025 high-quality single-nucleotide polymorphisms identified 77 marker–trait associations (MTAs), of which 10 were chosen as high-confidence MTAs as they had > 10% phenotypic variation with logarithm of odds (LOD) scores of more than five. Candidate-gene (CG) mining from high-confidence MTAs identified 180 unique gene models, of which 78 were differentially expressed (DEGs) with at least twofold change in expression under low-P over optimum-P. Of the 78-DEGs, 13 were thought to be putative CGs as they exhibited functional relevance to PUE traits. These CGs mainly encode for important proteins and their products involved in regulating root system architecture, P uptake, transport, and utilization. Promoter analysis from 1500 bp upstream of gene start site for 13 putative CGs revealed the presence of light responsive, salicylic-acid responsive, gibberellic-acid (GA)-responsive, auxin-responsive, and cold responsive cis-regulatory elements. High-confidence MTAs and putative CGs identified in this study can be employed in breeding programs to improve PUE traits in bread wheat. [ABSTRACT FROM AUTHOR]

Main conclusion: Expression profiling of NF-Y transcription factors during dehydration and salt stress in finger millet genotypes contrastingly differing in tolerance levels identifies candidate genes for further characterization and functional studies. The Nuclear Factor-Y (NF-Y) transcription factors are known for imparting abiotic stress tolerance in different plant species. However, there is no information on the role of this transcription factor family in naturally drought-tolerant crop finger millet (Eleusine coracana L.). Therefore, interpretation of expression profiles against drought and salinity stress may provide valuable insights into specific and/or overlapping expression patterns of Eleusine coracana Nuclear Factor-Y (EcNF-Y) genes. Given this, we identified 59 NF-Y (18 NF-YA, 23 NF-YB, and 18 NF-YC) encoding genes and designated them EcNF-Y genes. Expression profiling of these genes was performed in two finger millet genotypes, PES400 (dehydration and salt stress tolerant) and VR708 (dehydration and salt stress sensitive), subjected to PEG-induced dehydration and salt (NaCl) stresses at different time intervals (0, 6, and 12 h). The qRT-PCR expression analysis reveals that the six EcNF-Y genes namely EcNF-YA1, EcNF-YA5, EcNF-YA16, EcNF-YB6, EcNF-YB10, and EcNF-YC2 might be associated with tolerance to both dehydration and salinity stress in early stress condition (6 h), suggesting the involvement of these genes in multiple stress responses in tolerant genotype. In contrast, the transcript abundance of finger millet EcNF-YA5 genes was also observed in the sensitive genotype VR708 under late stress conditions (12 h) of both dehydration and salinity stress. Therefore, the EcNF-YA5 gene might be important for adaptation to salinity and dehydration stress in sensitive finger millet genotypes. Therefore, this gene could be considered as a susceptibility determinant, which can be edited to impart tolerance. The phylogenetic analyses revealed that finger millet NF-Y genes share strong evolutionary and functional relationship to NF-Ys governing response to abiotic stresses in rice, sorghum, maize, and wheat. This is the first report of expression profiling of EcNF-Ys genes identified from the finger millet genome and reveals potential candidate for enhancing dehydration and salt tolerance. [ABSTRACT FROM AUTHOR]

Key message: A total of 104 foxtail millet accessions were evaluated for 11 nutrients in three environments and 67 high-confidence marker–trait associations (MTAs) were identified. Six SNPs showed pleiotropic effect and associated with two or more nutrients, whereas 24 candidate genes were identified for 28 MTAs involving seven traits. Millets are known for their better nutritional profiles compared to major cereals. Foxtail millet (Setaria italica) is rich in nutrients essential to circumvent malnutrition and hidden hunger. However, the genetic determinants underlying this trait remain elusive. In this context, we evaluated 104 diverse foxtail millet accessions in three different environments (E1, E2, and E3) for 11 nutrients and genotyped with 30K SNPs. The genome-wide association study showed 67 high-confidence (Bonferroni-corrected) marker–trait associations (MTAs) for the nutrients except for phosphorus. Six pleiotropic SNPs were also identified, which were associated with two or more nutrients. Around 24 candidate genes (CGs) were identified for 28 MTAs involving seven nutrients. A total of 17 associated SNPs were present within the gene region, and five (5) were mapped in the exon of the CGs. Significant SNPs, desirable alleles and CGs identified in the present study will be useful in breeding programmes for trait improvement. [ABSTRACT FROM AUTHOR]

Foxtail millet (Setaria italica L.) has emerged as a model system to understand its adaptation to environmental stresses in the past decade. However, studies on understanding the molecular mechanism underlying the adaptation to dehydration stress and the regulatory network involved in the process remain elusive. In the present study, RNA-seq was performed during dehydration stress in the tolerant (IC4) and sensitive (IC41) cultivars at different time points (0, 6, and 12 h). A total of 2467 and 3318 differentially expressed genes (DEGs) were identified in IC4, and 2535 and 5572 in IC41 at 6 h and 12 h compared to control (0 h), respectively. Gene ontology (GO) analysis revealed that the DEGs were enriched in water transport, response to water deprivation, oxidative stress, amino acid and sugar transport, lipid biosynthesis, and regulation of stomatal opening. Pathway analysis suggested a significant modulation of genes involved in the metabolism of glutathione and tryptophan and biosynthesis of flavonoid, ascorbate, arginine, and proline in IC4 compared to IC41. Genes encoding for DIVARICATA, SBP family protein (teosinte glume architecture 1), and SRS family proteins (LATERAL ROOT PRIMORDIUM 1 and SHI-RELATED SEQUENCE 1) were found to be exclusively upregulated in IC4 during dehydration stress. Gene co-expression networks constructed based on the expression data showed the key modules and hubs that play critical roles during dehydration stress. Altogether, the present study has identified key genes, pathways, and regulatory modules that would serve as a base for further studies to gain insights into the dehydration-responsive molecular circuitry in foxtail millet. [ABSTRACT FROM AUTHOR]

High temperature-induced crop failures are prominent nowadays in major staples, including rice, wheat, and maize; however, crops such as foxtail millet (Setaria italica) are resilient to temperature stress. In this study, a novel small heat shock protein of foxtail millet, SisHSP21.9, is identified and characterized for its role in conferring tolerance to high-temperature stress. SisHSP21.9 is a panicoid-specific gene, which is highly upregulated during high-temperature in leaves, and the protein is localized in the chloroplast. Its expression is directly regulated by heat shock factor, SiHSFA2e, during temperature stress. Further, overexpression of SiHSP21.9 in rice enhanced the survival of transgenics during high-temperature stress (> 80% survival frequency), and the transgenic lines showed improved plant architecture and overall grain yield. Compared to WT plants, transgenic lines maintained optimal photosynthesis rates with higher photosystem efficiencies at high temperatures, and this is conferred through protecting the components of photosystems, chlorophyll-binding proteins, and chloroplast-localized functional proteins by SisHSP21.9. Prolonged high-temperature stress showed minimal damage to chloroplast proteins resulting in comparatively lower yield loss (35–37%) in transgenic lines. Altogether, the study suggests that SisHSP21.9 is a potential candidate for designing thermotolerant crops for climate-resilient agriculture; however, further research is needed because tolerance to abiotic stresses is polygenic. [ABSTRACT FROM AUTHOR]

Adverse environmental conditions greatly influence crop production every year and threaten food security. Plants have a range of signaling networks to combat these stresses, in which several stress-responsive genes and regulatory proteins function together. One such important family of proteins, the Stress Associated Protein (SAP) family, has been identified as a novel regulator of multiple stresses. The SAPs possess a characteristic N-terminal A20 zinc-finger domain combined with either AN1 or C2H2 at the C-terminus. SAPs provide tolerance against various abiotic stresses, including cold, salt, drought, heavy metal, and wounding. The majority of SAPs are stress-inducible and have a function in conferring stress tolerance in transgenics. The role of SAPs in regulating biotic stress responses is a newly emerging field among researchers. SAPs interact with many other proteins to execute their functions; however, the detailed mechanism of these interactions needs to be elucidated. In this context, the present review provides a detailed view of the evolution and functions of SAPs in plants. The involvement in crosstalk between abiotic and biotic stress signaling pathways makes SAPs ideal targets to develop crops with tolerance against multiple stresses without any yield penalty. Altogether, we provide current knowledge on SAPs for investigating their role in stress response, which can further be exploited to develop climate-resilient crops through transgene-based, breeding-mediated, or genome-editing approaches. [ABSTRACT FROM AUTHOR]

Background: Maruca vitrata is one of the potential insect pests that cause devastating losses to legume cultivation worldwide. Gene functional studies facilitate dissecting the molecular mechanisms underlying the infection process and enable devising appropriate molecular strategies to control this insect pest. Expression profiling using quantitative real-time PCR (qRT-PCR) provides insights into the functional characterization of target genes; however, ideal reference genes should be deployed in such studies to nullify the background variation and improve the accuracy of target gene expression. An ideal reference gene should have a stable expression across developmental stages, biological conditions, tissues, or experimental conditions. Methods and results: Given this, the stability of eight candidate reference genes was evaluated in M. vitrata at different developmental stages, diets, and sexes by qRT-PCR method, and the data was analyzed using four independent algorithms, namely GeNorm, NormFinder, BestKeeper, and ΔCt, and one comprehensive algorithm, RefFinder. Conclusion: The analysis showed that RP49 and RPL13 were the best suitable reference genes for studying target gene expression at different developmental stages. Further, the study identified RP49 and RPL24, and GAPDH and RPL24 as the ideal reference genes in M. vitrata fed with different diets and sexes, respectively. The reference genes reported in the present study will ensure the accuracy of target gene expression, and thus, will serve as an important resource for gene functional studies in M. vitrata. [ABSTRACT FROM AUTHOR]

Proteins regulate cellular and biological processes in all living organisms. More than 80% of the proteins interact with one another to perform their respective functions; therefore, studying the protein–protein-interaction has gained attention in functional characterization studies. Bimolecular fluorescence complement (BiFC) assay is widely adopted to determine the physical interaction of two proteins in vivo. Here, we developed a simple, yet effective BiFC assay for protein–protein-interaction using transient Agrobacterium-mediated-transformation of onion epidermal cells by taking case study of Rice-P-box-Binding-Factor (RPBF) and rice-seed-specific-bZIP (RISBZ) in vivo interaction. Our result revealed that both the proteins, i.e., RISBZ and RPBF, interacted in the nucleus and cytosol. These two transcription factors are known for their coordinate/synergistic regulation of seed-protein content via concurrent binding to the promoter region of the seed storage protein (SSP) encoding genes. We further validated our results with BiFC assay in Nicotiana by agroinfiltration method, which exhibited similar results as Agrobacterium-mediated-transformation of onion epidermal cells. We also examined the subcellular localization of RISBZ and RPBF to assess the efficacy of the protocol. The subcellular localization and BiFC assay presented here is quite easy-to-follow, reliable, and reproducible, which can be completed within 2–3 days without using costly instruments and technologies that demand a high skill set. [ABSTRACT FROM AUTHOR]

Key message: Improving the nutritional content of graminaceous crops is imperative to ensure nutritional security, wherein omics approaches play pivotal roles in dissecting this complex trait and contributing to trait improvement. Micronutrients regulate the metabolic processes to ensure the normal functioning of the biological system in all living organisms. Micronutrient deficiency, thereby, can be detrimental that can result in serious health issues. Grains of graminaceous crops serve as an important source of micronutrients to the human population; however, the rise in hidden hunger and malnutrition indicates an insufficiency in meeting the nutritional requirements. Improving the elemental composition and nutritional value of the graminaceous crops using conventional and biotechnological approaches is imperative to address this issue. Identifying the genetic determinants underlying the micronutrient biosynthesis and accumulation is the first step toward achieving this goal. Genetic and genomic dissection of this complex trait has been accomplished in major cereals, and several genes, alleles, and QTLs underlying grain micronutrient content were identified and characterized. However, no comprehensive study has been reported on minor cereals such as small millets, which are rich in micronutrients and other bioactive compounds. A comparative narrative on the reports available in major and minor Graminaceae species will illustrate the knowledge gained from studying the micronutrient traits in major cereals and provides a roadmap for dissecting this trait in other minor species, including millets. In this context, this review explains the progress made in studying micronutrient traits in major cereals and millets using omics approaches. Moreover, it provides insights into deploying integrated omics approaches and strategies for genetic improvement in micronutrient traits in graminaceous crops. [ABSTRACT FROM AUTHOR]

Ecofriendly approaches to control plant diseases using biopolymers are gaining momentum due to their non-toxic nature to the environment. The present study elucidates the potency of a sulfated polysaccharide, κ-carrageenan, obtained from the red seaweed Kappaphycus alvarezii, as an inducer of antioxidant defense and also chloroplast proteome against leaf spot disease in tomato. к-carrageenan (0.3%) treatment was very effective in reducing disease scores in tomato plants. Fluorescent microscopy of tomato leaves stained with Uvitex 2B (a chitin specific stain) revealed that foliar application of κ-carrageenan (0.3%) reduced colonization of the pathogen Septoria lycopersici. In addition, κ-carrageenan pretreatment followed by pathogen infection recorded a higher accumulation of calcium oxalate crystals. The treatment of κ-carrageenan resulted in the induction of H2O2 and superoxide anion compared to control or S. lycopersici-infected plants. The tomato leaves treated with κ-carrageenan showed higher activity of peroxidase enzyme. Furthermore, chloroplast proteome analysis by 2D-PAGE of control, S. lycopersici-infected, κ-carrageenan-treated, and к-carrageenan treatment followed by S. lycopersici-infected leaves of tomato showed differential expression of 31 proteins, of which 11 proteins were upregulated including acid phosphatase 1-like, C- terminal processing peptidase, GATA transcription factor 5, Calvin cycle protein CP12-1, Photosystem I reaction center subunit PSAK, and subunit of cytochrome B6-F complex iron-sulfur centers. These results indicated that κ-carrageenan could be a promising inducer of antioxidant defense and modulator of chloroplast proteome in tomato plants. [ABSTRACT FROM AUTHOR]

Phytohormones are ubiquitously involved in plant biological processes and regulate cellular signaling pertaining to unheralded environmental cues, such as salinity, drought, extreme temperature and nutrient deprivation. The association of phytohormones to nearly all the fundamental biological processes epitomizes the phytohormone syndicate as a candidate target for consideration during engineering stress endurance in agronomically important crops. The drought stress response is essentially driven by phytohormones and their intricate network of crosstalk, which leads to transcriptional reprogramming. This review is focused on the pivotal role of phytohormones in water deficit responses, including their manipulation for mitigating the effect of the stressor. We have also discussed the inherent complexity of existing crosstalk accrued among them during the progression of drought stress, which instigates the tolerance response. Therefore, in this review, we have highlighted the role and regulatory aspects of various phytohormones, namely abscisic acid, auxin, gibberellic acid, cytokinin, brassinosteroid, jasmonic acid, salicylic acid, ethylene and strigolactone, with emphasis on drought stress tolerance. [ABSTRACT FROM AUTHOR]

Key message: Analysis of autophagy-related genes in tomato shows the involvement of SlATG18f in leaf curl disease tolerance and a CAPS marker developed from this gene demonstrates its usefulness in marker-assisted selection. Autophagy is a highly conserved catabolic process regulating cellular homeostasis and adaptation to different biotic and abiotic stress. Several autophagy-related proteins (ATGs) are reported to be involved in autophagic processes, and considering their importance in regulating growth and stress adaptation, these proteins have been identified and characterized in several plant species. However, there is no information available on the role of autophagy-related proteins regulating the tolerance of tomato to tomato leaf curl disease (ToLCD). Given this, the present genome-wide study identified thirty ATG-encoding genes (SlATG) in tomato, followed by their functional characterization. Expression profiling of the SlATG genes in contrasting tomato cultivars subjected to virus infection showed a 4.5-fold upregulation of SlATG18f in the tolerant cultivar. Further, virus-induced gene silencing of SlATG18f in the tolerant cultivar conferred disease susceptibility, which suggested the role of this gene in Tomato leaf curl New Delhi virus tolerance. Comparison of the gene sequence of both tolerant and susceptible cultivars along with the 5′ upstream regions identified an SNP (A/T) at -2916 upstream of the start codon. A cleaved amplified polymorphic sequence (CAPS) marker was developed targeting this region, which showed a significant association with the tolerance characteristics in the tomato germplasm (R2 = 0.1787). Altogether, the study identified a potential gene that could be used to develop ToLCNDV tolerant tomato cultivars using transgene-based or marker-assisted breeding-based approaches. [ABSTRACT FROM AUTHOR]

Elicitor-induced defense response against potential plant pathogens has been widely reported in several crop plants; however, transcriptome dynamics underlying such defense response remains elusive. Our previous study identified and characterized a novel elicitor, κ-carrageenan, from Kappaphycus alvarezii, a marine red seaweed. Our preliminary studies have shown that the elicitor-treatment enhances the tolerance of a susceptible tomato cultivar to Septoria lycopersici (causative agent of leaf spot disease). To gain further insights into the genes regulated during elicitor treatment followed by pathogen infection, we have performed RNA-Seq experiments under different treatments, namely, control (untreated and uninfected), elicitor treatment, pathogen infection alone, and elicitor treatment followed by pathogen infection. To validate the results, forty-three genes belonging to five different classes, namely, ROS activating and detoxifying enzyme encoding genes, DEAD-box RNA helicase genes, autophagy-related genes, cysteine proteases, and pathogenesis-related genes, were chosen. Expression profiling of each gene was performed using qRT-PCR, and the data was correlated with the RNA-seq data. Altogether, the study has pinpointed a repertoire of genes that could be potential candidates for further functional characterization to provide insights into novel elicitor-induced fungal defense and develop transgenic lines resistant to foliar diseases. [ABSTRACT FROM AUTHOR]

Main conclusion: Present review describes the molecular tools and strategies deployed in the trait discovery and improvement of major crops. The prospects and challenges associated with these approaches are discussed. Crop improvement relies on modulating the genes and genomic regions underlying key traits, either directly or indirectly. Direct approaches include overexpression, RNA interference, genome editing, etc., while breeding majorly constitutes the indirect approach. With the advent of latest tools and technologies, these strategies could hasten the improvement of crop species. Next-generation sequencing, high-throughput genotyping, precision editing, use of space technology for accelerated growth, etc. had provided a new dimension to crop improvement programmes that work towards delivering better varieties to cope up with the challenges. Also, studies have widened from understanding the response of plants to single stress to combined stress, which provides insights into the molecular mechanisms regulating tolerance to more than one stress at a given point of time. Altogether, next-generation genetics and genomics had made tremendous progress in delivering improved varieties; however, the scope still exists to expand its horizon to other species that remain underutilized. In this context, the present review systematically analyses the different genomics approaches that are deployed for trait discovery and improvement in major species that could serve as a roadmap for executing similar strategies in other crop species. The application, pros, and cons, and scope for improvement of each approach have been discussed with examples, and altogether, the review provides comprehensive coverage on the advances in genomics to meet the ever-growing demands for agricultural produce. [ABSTRACT FROM AUTHOR]

The exponential spread of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emphasizes the immediate need for effective antiviral drugs and vaccines that could control and prevent the spread of this pandemic. Several new and repurposed drugs are being tested for their effectiveness in the treatment regime, and the development of vaccines is underway. The availability of genome sequence information of the virus and the identification of potential targets to neutralize and eradicate the infection have enabled the search for novel as well as existing molecules to perform the desired function. However, the application of plants in the development of potential biomolecules, such as antibiotics and vaccines, is limited. Traditional medicines involving plant-based formulations have proven successful in boosting immunity and providing tolerance to virus infections. Still, in-depth studies are not available to explore the bioactive compounds of plant origin and their mechanism of action. Given this, the current opinion article conveys our thoughts and perspectives on the promising usage of plant-based biomolecules in circumventing SARS-CoV-2, and how these molecules can work synergistically with other potential drugs for treating SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Aquaporins are versatile proteins involved in several biological as well as molecular functions, and they have been extensively studied in various plant systems. Increasing evidences indicate their role in biotic and abiotic stresses, and therefore, studying these proteins in a naturally stress-tolerant crop would provide further insights into the roles of this important protein family. Given this, the present study was performed in foxtail millet (Setaria italica), a model plant for studying biofuel, stress tolerance, and C4 photosynthetic traits. The study identified 12 plasma membrane intrinsic proteins (PIPs), 11 tonoplast intrinsic proteins (TIPs), 13 NOD26-like intrinsic proteins (NIPs), and 3 small basic intrinsic proteins (SIPs) in foxtail millet. The identified proteins and their corresponding genes were characterized using in silico approaches such as chromosomal localization, analysis of gene and protein properties, phylogenetic analysis, promoter analysis, and RNA-seq-derived expression profiling. The candidate genes identified through these analyses were studied for their expression in response to abiotic stresses (dehydration, salinity, and heat) as well as hormone treatments (abscisic acid, methyl jasmonate, and salicylic acid) in two contrasting cultivars of foxtail millet. The study showed that SiPIP3;1 and SiSIP1;1 were differentially expressed in both the cultivars in response to stress and hormone treatments. Overexpression of these genes in a heterologous yeast system also demonstrated that the transgenic cells were able to tolerate dehydration as well as salt stress which suggests the involvement of these proteins in the tolerance mechanism. Overall, the present study provides insights into structure and organization of the aquaporin gene family in foxtail millet and highlights the potential candidate genes for further functional characterizations. [ABSTRACT FROM AUTHOR]

Post-translational modifications namely ubiquitination, phosphorylation, methylation and acetylation play distinct roles in regulating the growth and development of plants. Among these, the ubiquitination regulates the abundance, activities, subcellular compartmentalization and trafficking of regulatory proteins involved in diverse developmental as well as stress-responsive processes. The ubiquitin-proteasome system (UPS) involves five essential components namely ubiquitin, ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), ubiquitin ligase (E3) and the intact 26S proteasome. The E3 ubiquitin ligase is the major component of UPS that recognizes and tethers poly-ubiquitins on the target proteins. Owing to its specificity of substrate recognition, the E3 ubiquitin ligase contributes not only to the proteome plasticity of the cell but also regulates the plant's response to environmental cues. In this context, the review summarizes the components involved in UPS and elaborates the role of E3 ubiquitin ligase in biotic and abiotic stress responses. [ABSTRACT FROM AUTHOR]

Armadillo repeat family is well-characterized in several plant species for their involvement in multiple regulatory processes including growth, development, and stress response. We have previously shown a three-fold higher expression of ARM protein-encoding in tomato cultivar tolerant to tomato leaf curl New Delhi virus (ToLCNDV) compared to susceptible cultivar upon virus infection. This suggests the putative involvement of ARM proteins in defense response against virus infection; however, no comprehensive investigation has been performed to address this inference. In the present study, we have identified a total of 46 ARM-repeat proteins (SlARMs), and 41 U-box-containing proteins (SlPUBs) in tomato. These proteins and their corresponding genes were studied for their physicochemical properties, gene structure, domain architecture, chromosomal localization, phylogeny, and cis-regulatory elements in the upstream promoter region. Expression profiling of candidate genes in response to ToLCNDV infection in contrasting tomato cultivars showed significant upregulation of SlARM18 in the tolerant cultivar. Virus-induced gene silencing of SlARM18 in the tolerant tomato cultivar conferred susceptibility, which suggests the involvement of this gene in resistance mechanism. Further studies are underway to functionally characterize SlARM18 to delineate its precise role in defense mechanism. [ABSTRACT FROM AUTHOR]

Key message: Genome-wide methylation analysis of foxtail millet cultivars contrastingly differing in salinity tolerance revealed DNA demethylation events occurring in tolerant cultivar under salinity stress, eventually modulating the expression of stress-responsive genes. Abstract: Reduced productivity and significant yield loss are the adverse effects of environmental conditions on physiological and biochemical pathways in crop plants. In this context, understanding the epigenetic machinery underlying the tolerance traits in a naturally stress tolerant crop is imperative. Foxtail millet ( Setaria italica) is known for its better tolerance to abiotic stresses compared to other cereal crops. In the present study, methylation-sensitive amplified polymorphism (MSAP) technique was used to quantify the salt-induced methylation changes in two foxtail millet cultivars contrastingly differing in their tolerance levels to salt stress. The study highlighted that the DNA methylation level was significantly reduced in tolerant cultivar compared to sensitive cultivar. A total of 86 polymorphic MSAP fragments were identified, sequenced and functionally annotated. These fragments showed sequence similarity to several genes including ABC transporter, WRKY transcription factor, serine threonine-protein phosphatase, disease resistance, oxidoreductases, cell wall-related enzymes and retrotransposon and transposase like proteins, suggesting salt stress-induced methylation in these genes. Among these, four genes were chosen for expression profiling which showed differential expression pattern between both cultivars of foxtail millet. Altogether, the study infers that salinity stress induces genome-wide DNA demethylation, which in turn, modulates expression of corresponding genes. [ABSTRACT FROM AUTHOR]

Post-transcriptional control of gene expression is achieved through RNA interference where the activities of Dicer-like (DCL), Argonautes (AGO) and RNA-dependent RNA polymerases (RDRs) are significant. Hence, considering the importance of DCL, AGO and RDRs, a comprehensive genome-wide analysis was performed in foxtail millet. The study identified 8 DCL, 19 AGO and 11 RDR genes. Phylogenetic and domain analysis provided interesting information on the evolutionary and structural aspects of these proteins. The orthologs of Setaria italica DCL ( SiDCL), AGO ( SiAGO) and RDRs ( SiRDRs) were identified in sorghum, maize and rice, and the evolutionary relationships among the orthologous gene pairs were investigated. Promoter analysis of SiDCL, SiAGO and SiRDR genes revealed the presence of unique and common cis-acting elements at the upstream of respective gene sequences, which serves as binding sites for several developmental and stress-related transcription factors. In silico expression profiling using RNA-sequence data showed tissue-specific expression patterns of these genes in foxtail millet. Candidate genes representing each sub-family were chosen for expression analysis through quantitative real-time PCR (qRT-PCR) under salinity, dehydration and hormonal treatments. It revealed the differential expression pattern of candidate genes at different time points of stresses. This is the first report on genome-wide analysis of SiDCL, SiAGO and SiRDR gene families in foxtail millet, which provides basic genomic information and insights into the putative roles of these genes in abiotic stresses. The present study will serve as a base for further functional characterization of these gene families in foxtail millet and related grass species. [ABSTRACT FROM AUTHOR]

Key message: Recent advances in Setaria genomics appear promising for genetic improvement of cereals and biofuel crops towards providing multiple securities to the steadily increasing global population. Abstract: The prominent attributes of foxtail millet ( Setaria italica, cultivated) and green foxtail ( S. viridis, wild) including small genome size, short life-cycle, in-breeding nature, genetic close-relatedness to several cereals, millets and bioenergy grasses, and potential abiotic stress tolerance have accentuated these two Setaria species as novel model system for studying C photosynthesis, stress biology and biofuel traits. Considering this, studies have been performed on structural and functional genomics of these plants to develop genetic and genomic resources, and to delineate the physiology and molecular biology of stress tolerance, for the improvement of millets, cereals and bioenergy grasses. The release of foxtail millet genome sequence has provided a new dimension to Setaria genomics, resulting in large-scale development of genetic and genomic tools, construction of informative databases, and genome-wide association and functional genomic studies. In this context, this review discusses the advancements made in Setaria genomics, which have generated a considerable knowledge that could be used for the improvement of millets, cereals and biofuel crops. Further, this review also shows the nutritional potential of foxtail millet in providing health benefits to global population and provides a preliminary information on introgressing the nutritional properties in graminaceous species through molecular breeding and transgene-based approaches. [ABSTRACT FROM AUTHOR]

DNA markers are important in molecular breeding, and, hence, considering its prominence, a variety of DNA-based molecular markers have been explored and developed for expediting crop improvement programs. microRNA (miRNA)-based molecular marker is a type of functional markers exploited predominantly in animal sciences, but reported in very few plants. Considering the efficacy, stability and transferability potential of the miRNA-based markers, the present study was conducted to develop these markers in the model crop foxtail millet. The pre-miRNA sequences of foxtail millet and other related grasses including rice, maize, wheat, sorghum and Brachypodium were retrieved and aligned for identifying the conserved regions. One hundred and seventy-six primer pairs were designed for these consensus sequences, and all these 176 miRNA-based markers were mapped onto foxtail millet genome. Of the 176 markers, 66 were chosen for further experimentations based on representing the nine chromosomes of foxtail millet and presence of highly conserved regions. All the 66 markers showed 100 % amplification in five cultivars of foxtail millet. Moreover, all the markers showed a higher level of cross-genera transferability potential with an average of ~67 % in millets and non-millet species. This is the first report on the development of novel miRNA-based markers in foxtail millet. Promisingly, these markers would serve as novel genotyping tool for various molecular breeding approaches aiming at crop improvement in millets and non-millet species. [ABSTRACT FROM AUTHOR]

Foxtail millet has recently been regarded as a model crop for studying the systems biology of millets and bioenergy grass species. For expediting the functional genomic studies in this model crop as well as in the related millets and bioenergy grasses, we have developed a comprehensive transcription factor database. Our foxtail millet transcription factors database (FmTFDb: ) encompasses 2,297 putative TFs in 55 families along with its sequence features, chromosomal locations, tissue-specific gene expression data, gene ontology (GO) assignment, and phylogeny. FmTFDb is intended to provide the users an unrestricted public access in retrieving and visualizing the individual members of a TF family through a set of query interfaces and analysis tools, including the BLAST search, annotation query interfaces, and tools to identify enriched GO terms and to visualize physical maps. This FmTFDb will serve as a promising central resource for researchers as well as breeders who are dedicated towards crop improvement of millets and bioenergy grasses. [ABSTRACT FROM AUTHOR]

CH type of zinc finger transcription factors (TFs) play crucial roles in plant stress response and hormone signal transduction. Hence considering its importance, genome-wide investigation and characterization of CH zinc finger proteins were performed in Arabidopsis, rice and poplar but no such study was conducted in foxtail millet which is a C Panicoid model crop well known for its abiotic stress tolerance. The present study identified 124 CH-type zinc finger TFs in foxtail millet ( SiC2H2) and physically mapped them onto the genome. The gene duplication analysis revealed that SiC2H2s primarily expanded in the genome through tandem duplication. The phylogenetic tree classified these TFs into five groups (I-V). Further, miRNAs targeting SiC2H2 transcripts in foxtail millet were identified. Heat map demonstrated differential and tissue-specific expression patterns of these SiC2H2 genes. Comparative physical mapping between foxtail millet SiC2H2 genes and its orthologs of sorghum, maize and rice revealed the evolutionary relationships of CH type of zinc finger TFs. The duplication and divergence data provided novel insight into the evolutionary aspects of these TFs in foxtail millet and related grass species. Expression profiling of candidate SiC2H2 genes in response to salinity, dehydration and cold stress showed differential expression pattern of these genes at different time points of stresses. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA)-guided post-transcriptional regulation is an important mechanism of gene regulation during multiple biological processes including response to abiotic stresses. Foxtail millet is a model crop, which is genetically closely related to several bioenergy grasses and also known for its potential abiotic stress tolerance. Hence deciphering the role of miRNAs in regulating stress-responsive mechanism would enable imparting durable stress tolerance in both millets and bioenergy grasses. Considering this, a comprehensive genome-wide in silico analysis was performed in foxtail millet which identified 355 mature miRNAs along with their secondary structure as well as corresponding targets. Predicted miRNA targets were found to encode various DNA binding proteins, transcription factors or important functional enzymes, which could be the crucial regulators in plant abiotic stress responses. All the 355 miRNAs were physically mapped onto the foxtail millet genome and in silico tissue-specific expression for these miRNAs were studied. Comparative mapping of the 355 miRNAs between foxtail millet and other related grass species would assist miRNA studies in these genetically closely-related plants. Expression profiling was performed for eight candidate miRNAs under diverse abiotic stresses in foxtail millet, which unravelled the putative involvement of these miRNAs in stress tolerance. With an aim of providing the generated miRNA marker information to the global scientific community, a foxtail millet MiRNA Database (FmMiRNADb: ) has also been constructed. Overall, the present study provides novel insights onto the role of miRNAs in abiotic stress tolerance and would promisingly expedite research on post-transcriptional regulation of stress-related genes in millets and bioenergy grasses. [ABSTRACT FROM AUTHOR]

Key message: Association analyses accounting for population structure and relative kinship identified eight SSR markers ( p < 0.01) showing significant association ( R = 18 %) with nine agronomic traits in foxtail millet. Abstract: Association mapping is an efficient tool for identifying genes regulating complex traits. Although association mapping using genomic simple sequence repeat (SSR) markers has been successfully demonstrated in many agronomically important crops, very few reports are available on marker-trait association analysis in foxtail millet. In the present study, 184 foxtail millet accessions from diverse geographical locations were genotyped using 50 SSR markers representing the nine chromosomes of foxtail millet. The genetic diversity within these accessions was examined using a genetic distance-based and a general model-based clustering method. The model-based analysis using 50 SSR markers identified an underlying population structure comprising five sub-populations which corresponded well with distance-based groupings. The phenotyping of plants was carried out in the field for three consecutive years for 20 yield contributing agronomic traits. The linkage disequilibrium analysis considering population structure and relative kinship identified eight SSR markers ( p < 0.01) on different chromosomes showing significant association ( R = 18 %) with nine agronomic traits. Four of these markers were associated with multiple traits. The integration of genetic and physical map information of eight SSR markers with their functional annotation revealed strong association of two markers encoding for phospholipid acyltransferase and ubiquitin carboxyl-terminal hydrolase located on the same chromosome (5) with flag leaf width and grain yield, respectively. Our findings on association mapping is the first report on Indian foxtail millet germplasm and this could be effectively applied in foxtail millet breeding to further uncover marker-trait associations with a large number of markers. [ABSTRACT FROM AUTHOR]

Geminiviruses are widely distributed throughout the world and cause devastating yield losses in almost all the economically important crops. In this review, the newly identified roles of various novel plant factors and pathways participating in plant-virus interaction are summarized with a particular focus on the exploitation of various pathways involving ubiquitin/26S proteasome pathway, small RNA pathways, cell division cycle components, and the epigenetic mechanism as defense responses during plant-pathogen interactions. Capturing the information on these pathways for the development of strategies against geminivirus infection is argued to provide the basis for new genetic approaches to resistance. [ABSTRACT FROM AUTHOR]

Reference genes are standards for quantifying gene expression through quantitative real-time PCR (qRT-PCR); however, the variation observed in their expression levels is the major hindrance towards realising their effective use. Hence, a systematic validation of reference genes is required to ensure proper normalization. However, no such study has been conducted in foxtail millet [ Setaria italica (L.)], which has recently emerged as a model crop for genetic and genomic studies. In the present study, 8 commonly used reference genes were evaluated, including 18S ribosomal RNA, elongation factor-1α, Actin2, alpha tubulin, beta tubulin, translation factor, RNA polymerase II and adenine phosphoribosyl transferase. Expression stability of candidate internal control genes was investigated under salinity and dehydration treatments. The results obtained suggested a wide range of Ct values and variable expression of all reference genes. geNorm and NormFinder analysis had revealed that Act2 and RNA POL II are suitable reference genes for salinity stress-related studies and EF- 1α and RNA POL II are appropriate internal controls for dehydration stress-related expression analyses. These qualified reference genes has also been validated for relative quantification of 14- 3- 3 expression analysis which demonstrated their applicability. Thus, this is the first report on selection and validation of superior reference genes for qRT-PCR in foxtail millet under different abiotic stress conditions. [ABSTRACT FROM AUTHOR]

Epigenetics has become one of the hottest topics of research in plant functional genomics since it appears promising in deciphering and imparting stress-adaptive potential in crops and other plant species. Recently, numerous studies have provided new insights into the epigenetic control of stress adaptation. Epigenetic control of stress-induced phenotypic response of plants involves gene regulation. Growing evidence suggest that methylation of DNA in response to stress leads to the variation in phenotype. Transposon mobility, siRNA-mediated methylation and host methyltransferase activation have been implicated in this process. This review presents the current status of epigenetics of plant stress responses with a view to use this knowledge towards engineering plants for stress tolerance. [ABSTRACT FROM AUTHOR]

Plants are invaded by an array of pathogens of which only a few succeed in causing disease. The attack by others is countered by a sophisticated immune system possessed by the plants. The plant immune system is broadly divided into two, viz. microbial-associated molecular-patterns-triggered immunity (MTI) and effector-triggered immunity (ETI). MTI confers basal resistance, while ETI confers durable resistance, often resulting in hypersensitive response. Plants also possess systemic acquired resistance (SAR), which provides long-term defense against a broad-spectrum of pathogens. Salicylic-acid-mediated systemic acquired immunity provokes the defense response throughout the plant system during pathogen infection at a particular site. Trans-generational immune priming allows the plant to heritably shield their progeny towards pathogens previously encountered. Plants circumvent the viral infection through RNA interference phenomena by utilizing small RNAs. This review summarizes the molecular mechanisms of plant immune system, and the latest breakthroughs reported in plant defense. We discuss the plant-pathogen interactions and integrated defense responses in the context of presenting an integral understanding in plant molecular immunity. [ABSTRACT FROM AUTHOR]

Foxtail millet (Setaria italica), the second largest cultivated millet crop after pearl millet, is utilized for food and forage globally. Further, it is also considered as a model crop for studying agronomic, nutritional and biofuel traits. In the present study, a genome-wide association study (GWAS) was performed for ten important agronomic traits in 142 foxtail millet core eco-geographically diverse genotypes using 10 K SNPs developed through GBS-ddRAD approach. Number of SNPs on individual chromosome ranged from 844 (chromosome 5) to 2153 (chromosome 8) with an average SNP frequency of 25.9 per Mb. The pairwise linkage disequilibrium (LD) estimated using the squared-allele frequency correlations was found to decay rapidly with the genetic distance of 177 Kb. However, for individual chromosome, LD decay distance ranged from 76 Kb (chromosome 6) to 357 Kb (chromosome 4). GWAS identified 81 MTAs (marker-trait associations) for ten traits across the genome. High confidence MTAs for three important agronomic traits including FLW (flag leaf width), GY (grain yield) and TGW (thousand-grain weight) were identified. Significant pyramiding effect of identified MTAs further supplemented its importance in breeding programs. Desirable alleles and superior genotypes identified in the present study may prove valuable for foxtail millet improvement through marker-assisted selection. [ABSTRACT FROM AUTHOR]