Comparative Analysis of UntargetedMetabolomics in Tolerant and Sensitive Genotypes of Common Bean (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.) Seeds Exposed to Terminal Drought Stress

Many environmental stresses can affect the accumulation of metabolites in plants, including drought. In the present study, we found a great deal of variability in the seed metabolic profiles of the tolerant (Matterhorn, SB-DT2 and SB-DT3) common bean genotypes in comparison to the sensitive genotypes (Sawtooth, Merlot and Stampede) using ultrahigh performance liquid chromatographytandem mass spectrometry (UPLC-MS). The genotypes were grown in the field and subjected to drought stress after flowering (terminal drought stress). We aimed to investigate the accumulation of genotype-specific metabolites and related pathways under terminal drought stress by comparing tolerant and sensitive genotypes within a race. A total of 26 potential metabolites were identified across genotype comparisons. Significant metabolic pathways, including monobactam biosynthesis, flavone and flavonol biosynthesis, pentose phosphate pathway, C5-branched dibasic acid metabolism, cysteine and methionine metabolism, vitamin B6 metabolism and flavonoid biosynthesis, were derived from the enriched metabolites. Many of these metabolic pathways were specific and varied with genotype comparisons. SB-DT2 vs. stampede revealed more significant metabolites and metabolic pathways compared to Matterhorn vs. Sawtooth and SB-DT3 vs. Merlot under terminal drought stress. Our study provides useful information regarding the metabolite profiles of seeds and their related pathways in comparisons of tolerant and sensitive common bean genotypes under terminal drought conditions. Further research, including transcriptomic and proteomic analyses, may contribute to a better understanding of molecular mechanisms and nutritional differences among seeds of common bean genotypes grown under terminal drought conditions

Identification of expressed resistance gene-like sequences by data mining in 454-derived transcriptomic sequences of common bean (Phaseolus vulgaris L.)

<p>Abstract</p> <p>Background</p> <p>Common bean (<it>Phaseolus vulgaris </it>L.) is one of the most important legumes in the world. Several diseases severely reduce bean production and quality; therefore, it is very important to better understand disease resistance in common bean in order to prevent these losses. More than 70 resistance (<it>R</it>) genes which confer resistance against various pathogens have been cloned from diverse plant species. Most <it>R </it>genes share highly conserved domains which facilitates the identification of new candidate <it>R </it>genes from the same species or other species. The goals of this study were to isolate expressed <it>R </it>gene-like sequences (RGLs) from 454-derived transcriptomic sequences and expressed sequence tags (ESTs) of common bean, and to develop RGL-tagged molecular markers.</p> <p>Results</p> <p>A data-mining approach was used to identify tentative <it>P. vulgaris R </it>gene-like sequences from approximately 1.69 million 454-derived sequences and 116,716 ESTs deposited in GenBank. A total of 365 non-redundant sequences were identified and named as common bean (<it>P. vulgaris </it>= Pv) resistance gene-like sequences (PvRGLs). Among the identified PvRGLs, about 60% (218 PvRGLs) were from 454-derived sequences. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirmed that PvRGLs were actually expressed in the leaves of common bean. Upon comparison to <it>P. vulgaris </it>genomic sequences, 105 (28.77%) of the 365 tentative PvRGLs could be integrated into the existing common bean physical map. Based on the syntenic blocks between common bean and soybean, 237 (64.93%) PvRGLs were anchored on the <it>P. vulgaris </it>genetic map and will need to be mapped to determine order. In addition, 11 sequence-tagged-site (STS) and 19 cleaved amplified polymorphic sequence (CAPS) molecular markers were developed for 25 unique PvRGLs.</p> <p>Conclusions</p> <p>In total, 365 PvRGLs were successfully identified from 454-derived transcriptomic sequences and ESTs available in GenBank and about 65% of PvRGLs were integrated into the common bean genetic map. A total of 30 RGL-tagged markers were developed for 25 unique PvRGLs, including 11 STS and 19 CAPS markers. The expressed PvRGLs identified in this study provide a large sequence resource for development of RGL-tagged markers that could be used further for genetic mapping of disease resistant candidate genes and quantitative trait locus/loci (QTLs). This work also represents an additional method for identifying expressed RGLs from next generation sequencing data.</p

Comparative Transcriptome Analysis of Tolerant and Sensitive Genotypes of Common Bean (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.) in Response to Terminal Drought Stress

We conducted a genome-wide transcriptomic analysis of three drought tolerant and sensitive genotypes of common bean to examine their transcriptional responses to terminal drought stress. We then conducted pairwise comparisons between the root and leaf transcriptomes from the resulting tissue based on combined transcriptomic data from the tolerant and sensitive genotypes. Our transcriptomic data revealed that 491 (6.4%) DEGs (differentially expressed genes) were upregulated in tolerant genotypes, whereas they were downregulated in sensitive genotypes; likewise, 396 (5.1%) DEGs upregulated in sensitive genotypes were downregulated in tolerant genotypes. Several transcription factors, heat shock proteins, and chaperones were identified in the study. Several DEGs in drought DB (data Base) overlapped between genotypes. The GO (gene ontology) terms for biological processes showed upregulation of DEGs in tolerant genotypes for sulfate and drug transmembrane transport when compared to sensitive genotypes. A GO term for cellular components enriched with upregulated DEGs for the apoplast in tolerant genotypes. These results substantiated the temporal pattern of root growth (elongation and initiation of root growth), and ABA-mediated drought response in tolerant genotypes. KEGG (kyoto encyclopedia of genes and genomes) analysis revealed an upregulation of MAPK (mitogen activated protein kinase) signaling pathways and plant hormone signaling pathways in tolerant genotypes. As a result of this study, it will be possible to uncover the molecular mechanisms of drought tolerance in response to terminal drought stress in the field. Further, genome-wide transcriptomic analysis of both tolerant and sensitive genotypes will assist us in identifying potential genes that may contribute to improving drought tolerance in the common bean

Diversity of Diatom Communities in Delaware Tidal Wetland and Their Relationship to Water Quality

Diatoms are strongly influenced by water quality and serve as indicators of water quality degradation in freshwater systems. Here, sediment and water samples were collected from four sites in Blackbird Creek, DE, a salt marsh characterized as mostly freshwater to low saline brackish (&lt;8ppt). Recent changes in land use resulted in increased agricultural activity, suggesting the need to develop water quality indicators in this region. To test the hypothesis that diatom community composition changes seasonally with variations in water quality parameters, sediment and water samples were collected in 2009 and 2010 for analysis. Water temperature, salinity, pH, and dissolved oxygen were measured as well as water and sediment dissolved nutrient concentrations (nitrate, ammonia, and total and reactive phosphorous). DNA was extracted from sediments and changes in diatom community composition were evaluated by amplification of 18S rRNA gene using diatom-specific primers, followed by Terminal Restriction Fragment Length Polymorphism (TRFLP) analysis. Shannon (H') index for TRFLP profiles ranged from 2.5 to 3.0 and Simpson (Ds) index was 0.9 which infers moderate levels of diatom species richness and high diversity in these study sites. Although there were no water quality parameters that were significantly correlated with diatom community composition as determined by TRFLP patterns, temperature was the most highly correlated (r = 0.203). Dissolved oxygen, salinity, and pH of water also had moderate but insignificant impacts on the diatom community. Further analysis of cloned 18S rRNA sequences revealed the presence of diatom taxa that tolerate wide salinity ranges, and included Navicula, Cyclotella, Thalassiosira and Skeletonema. Entomoneis sp. were also present in the spring and fall seasons. Overall, results in this study demonstrate significant differences in water qualities among the study years but little change in diatom community composition between study sites and seasons, but may serve as a baseline for future studies

Genome-wide profiling of histone modifications (H3K9me2 and H4K12ac) and gene expression in rust (uromyces appendiculatus) inoculated common bean (Phaseolus vulgaris L)

Histone modifications such as methylation and acetylation play a significant role in controlling gene expression in unstressed and stressed plants. Genome-wide analysis of such stress-responsive modifications and genes in non-model crops is limited. We report the genome-wide profiling of histone methylation (H3K9me2) and acetylation (H4K12ac) in common bean (Phaseolus vulgaris L.) under rust (Uromyces appendiculatus) stress using two high-throughput approaches, chromatin immunoprecipitation sequencing (ChIP-Seq) and RNA sequencing (RNA-Seq). ChIP-Seq analysis revealed 1,235 and 556 histone methylation and acetylation responsive genes from common bean leaves treated with the rust pathogen at 0, 12 and 84 hour-after-inoculation (hai), while RNA-Seq analysis identified 145 and 1,763 genes differentially expressed between mock-inoculated and inoculated plants. The combined ChIP-Seq and RNA-Seq analyses identified some key defense responsive genes (calmodulin, cytochrome p450, chitinase, DNA Pol II, and LRR) and transcription factors (WRKY, bZIP, MYB, HSFB3, GRAS, NAC, and NMRA) in bean-rust interaction. Differential methylation and acetylation affected a large proportion of stress-responsive genes including resistant (R) proteins, detoxifying enzymes, and genes involved in ion flux and cell death. The genes identified were functionally classified using Gene Ontology (GO) and EuKaryotic Orthologous Groups (KOGs). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified a putative pathway with ten key genes involved in plant-pathogen interactions. This first report of an integrated analysis of histone modifications and gene expression involved in the bean-rust interaction as reported here provides a comprehensive resource for other epigenomic regulation studies in non-model species under stress

Bioinformatics Tools and Genomic Resources Available in Understanding the Structure and Function of Gossypium

Cotton is economically and evolutionarily important crop for its fiber. In order to improve fiber quality and yield, and to exploit the natural genetic potential inherent in genotypes, understanding genome structure and function of cultivated cotton is important. In order to achieve this, a functional understanding of bioinformatics resources such as databases, software solutions, and analysis tools is required. But currently, there are very few unified reports on bioinformatics tools and even fewer repositories to access cotton genomic information. Also, resourceful developers and bioinformatics scientists actively addressing complex genomic challenges in cotton genomes are much in need. The primary goal of this chapter is to provide a review of such tools and resources for analyzing the structure and function of the cotton genome with preferential emphasis on this complex and economically important plant species. This discourse begins with a description of concurrent advances in high‐throughput genome sequencing and bioinformatics analyses and focuses on four major sections covering bioinformatics tools and resources for analysis of: (1) genomes; (2) transcriptomes; (3) small RNAs; and (4) epigenomes. In each section, recent advances in cotton have been discussed. Cotton genome sequencing and annotation efforts are outlined within these sections. This review discusses the availability of genome information of both diploid and tetraploid species that have impelled cotton genome research into the post‐genomics era, opening new avenues for exploring regulatory mechanisms associated with fine‐tuning of gene expression of fiber‐related genes. Finally, the potential impacts of these rapid advances, especially the challenges in handling and analyzing the large datasets are discussed

Identification and analysis of common bean (Phaseolus vulgaris L.) transcriptomes by massively parallel pyrosequencing

Common bean (Phaseolus vulgaris) is the most important food legume in the world. Although this crop is very important to both the developed and developing world as a means of dietary protein supply, resources available in common bean are limited. Global transcriptome analysis is important to better understand gene expression, genetic variation, and gene structure annotation in addition to other important features. However, the number and description of common bean sequences are very limited, which greatly inhibits genome and transcriptome research. Here we used 454 pyrosequencing to obtain a substantial transcriptome dataset for common bean

Comparative Analysis of Untargeted Metabolomics in Tolerant and Sensitive Genotypes of Common Bean (Phaseolus vulgaris L.) Seeds Exposed to Terminal Drought Stress

Many environmental stresses can affect the accumulation of metabolites in plants, including drought. In the present study, we found a great deal of variability in the seed metabolic profiles of the tolerant (Matterhorn, SB-DT2 and SB-DT3) common bean genotypes in comparison to the sensitive genotypes (Sawtooth, Merlot and Stampede) using ultrahigh performance liquid chromatography&minus;tandem mass spectrometry (UPLC-MS). The genotypes were grown in the field and subjected to drought stress after flowering (terminal drought stress). We aimed to investigate the accumulation of genotype-specific metabolites and related pathways under terminal drought stress by comparing tolerant and sensitive genotypes within a race. A total of 26 potential metabolites were identified across genotype comparisons. Significant metabolic pathways, including monobactam biosynthesis, flavone and flavonol biosynthesis, pentose phosphate pathway, C5-branched dibasic acid metabolism, cysteine and methionine metabolism, vitamin B6 metabolism and flavonoid biosynthesis, were derived from the enriched metabolites. Many of these metabolic pathways were specific and varied with genotype comparisons. SB-DT2 vs. stampede revealed more significant metabolites and metabolic pathways compared to Matterhorn vs. Sawtooth and SB-DT3 vs. Merlot under terminal drought stress. Our study provides useful information regarding the metabolite profiles of seeds and their related pathways in comparisons of tolerant and sensitive common bean genotypes under terminal drought conditions. Further research, including transcriptomic and proteomic analyses, may contribute to a better understanding of molecular mechanisms and nutritional differences among seeds of common bean genotypes grown under terminal drought conditions