Unknown,Transcriptomics,Genomics,Proteomics

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The evolution of spinable cotton fiber entailed prolonged development and a novel metabolism

ABSTRACT: exceptional example of evolutionary innovation is the single-celled seed trichome in Gossypium ("cotton fiber"). We have used fiber development in Gossypium as a system to understand how morphology can rapidly evolve. Fiber has undergone considerable morphological changes between the short, tightly adherent fibers of G. longicalyx and the derived long, spinable fibers of its closest relative, G. herbaceum, that facilitated cotton domestication. We conducted comparative gene expression profiling across a developmental time-course of fibers from G. longicalyx and G. herbaceum using microarrays with ~ 22,000 genes. Expression changes between stages were temporally protracted in G. herbaceum relative to G. longicalyx, reflecting a prolongation of the ancestral developmental program. Gene expression and GO analyses showed that many genes involved with stress responses were up-regulated early in G. longicalyx fiber development. Several candidate genes up-regulated in G. herbaceum have been implicated in regulating redox levels and cell elongation processes. Three genes previously shown to modulate hydrogen peroxide levels were consistently expressed in domesticated and wild cotton species with long fibers but expression was not detected by qRT-PCR in wild species with short fibers. Hydrogen peroxide is important for cell elongation, but at high concentrations it becomes toxic, activating stress processes that may lead to early onset of secondary cell wall synthesis and the end of cell elongation. These observations suggest that the evolution of long spinable fibers in cotton was accompanied by novel expression of genes assisting in the regulation of reactive oxygen species levels. Our data suggest a model for the evolutionary origin of a novel morphology through differential gene regulation causing prolongation of an ancestral developmental program. Keywords: Cotton, fiber, evolution, time-point, comparative genomic hybridization, stress response genes, H2O2 A balanced developmental loop design for microarray analysis was performed. For G. herbaceum (A1) and G. longicalyx (F), four fiber developmental time-points, 5, 10, 20 and 25 DPA were sampled. Within each species, hybridizations were performed between each pair of consecutive developmental stages by labeling one with Cy5 and the other with Cy3, and by closing the loop with a comparison of 25 and 5 dpa. In addition, 2 hybridizations were done between species at each time-point, using a dye swap for each pair. With three biological replications and 16 slides each, we generated gene expression data from a total of 48 microarrays.

ORGANISM(S): Gossypium herbaceum

SUBMITTER: Guanjing Hu

PROVIDER: E-GEOD-10228 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The evolution of spinnable cotton fiber entailed prolonged development and a novel metabolism.

Hovav Ran R Udall Joshua A JA Chaudhary Bhupendra B Hovav Einat E Flagel Lex L Hu Guanjing G Wendel Jonathan F JF

PLoS genetics 20080201 2

A central question in evolutionary biology concerns the developmental processes by which new phenotypes arise. An exceptional example of evolutionary innovation is the single-celled seed trichome in Gossypium ("cotton fiber"). We have used fiber development in Gossypium as a system to understand how morphology can rapidly evolve. Fiber has undergone considerable morphological changes between the short, tightly adherent fibers of G. longicalyx and the derived long, spinnable fibers of its closest ...[more]

PMID: 18248099

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Project description:Five allotetraploid cotton species have adapted, through their transcriptional responses, to unique environments with distinct levels of inherent abiotic stresses. The transcriptional responses of leaf and root tissue in five allotetraploid cotton species (Gossypium hirsutum, G. barbadense, G. tomentosum, G. mustelinum, and G. darwinii) under salt stress have been investigated in this study using cotton long oligonucleotide microarrays. Physiological responses to salinity such as stomatal conductance, ion and osmoprotectant contents were also measured as indicators of imposed stress. Accessions from these five cotton species were hydroponically grown and gradually introduced to a NaCl treatment (15 dS m-1). The microarray results identified 2721 and 2460 differentially expressed genes under salt stress that were significant in leaf and root tissue, respectively. Many of these genes were classified under gene ontology (GO) categories that suggest abiotic stress. These allotetraploid cottons shared transcriptional responses to salinity, but also showed responses that were species-specific. No consistent differences in transcriptional response among the previously estimated phylogenetic branches were found. Stomatal conductance, ion accumulation, and betaine, trigonelline, and trehalose contents also indicated salt stress. This global assessment of transcriptional and physiological responses to salt stress of these cotton species may identify possible gene targets for crop improvement and evolutionary studies of cotton. Keywords: CEGC Cotton oligo salt stress The transcriptional responses of leaf and root tissue in five allotetraploid cotton species (Gossypium hirsutum, G. barbadense, G. tomentosum, G. mustelinum, and G. darwinii) under salt stress have been investigated in this study using cotton long oligonucleotide microarrays. Physiological responses to salinity such as stomatal conductance, ion and osmoprotectant contents were also measured as indicators of imposed stress. Accessions from these five cotton species were hydroponically grown and gradually introduced to a NaCl treatment (15 dS m-1).

Project description:Background MeCP2, methyl-CpG-binding protein 2, binds to methylated cytosines at CpG dinucleotides, as well as to unmethylated DNA, and affects chromatin condensation. MECP2 mutations in females lead to Rett syndrome, a neurological disorder characterized by developmental stagnation and regression, loss of purposeful hand use and speech, stereotypic hand movements, deceleration of brain growth, autonomic dysfunction and seizures. Most mutations occur de novo during spermatogenesis. Located at Xq28, MECP2 is subject to X inactivation, and affected females are mosaic. Rare hemizygous males suffer from a severe congenital encephalopathy. Methods To identify pathways mis-regulated by MeCP2 deficiency, microarray-based global gene expression studies were carried out on cerebellum of Mecp2 mutant mice. We compared transcript levels in mutant/wildtype male sibs of two different MeCP2-deficient mouse models at 2, 4 and 8 weeks of age. Increased transcript levels were evaluated by real-time quantitative RT-PCR. Chromatin immunoprecipitation assays were used to document in vivo MeCP2 binding to promoter regions of candidate target genes. Results In the mutants, several hundred genes showed altered expression levels. Twice as many were increased than decreased, and only 27 genes were differentially expressed at more than one time point. The number of misregulated genes was 30% lower in mice with an exon 3 deletion (Mecp2tm1.1Jae) than in mice with a larger deletion (Mecp2tm1.1Bird). Between the mutants, few misregulated genes overlapped at each time point. Real-time quantitative RT-PCR assays validated increased transcript levels for four genes: Irak1, interleukin-1 receptor-associated kinase 1; Fxyd1, phospholemman, associated with Na, K-ATPase; Reln, encoding reelin, an extracellular signaling molecule essential for neuronal lamination and synaptic plasticity; and Gtl2/Meg3, an imprinted maternally expressed non-translated RNA that serves as a host gene for C/D box snoRNAs and microRNAs. Chromatin immunoprecipitation assays documented in vivo MeCP2 binding to promoter regions of Fxyd1, Reln, and Gtl2. Conclusions Transcriptional profiling of cerebellum failed to detect significant global changes in Mecp2-mutant mice. Increased transcript levels of Irak1, Fxyd1, Reln, and Gtl2 may contribute to the neuronal dysfunction in MeCP2-deficient mice and individuals with Rett syndrome. Our data provide testable hypotheses for future studies of the regulatory or signaling pathways that these genes act on. A genetic modification design type is where an organism(s) has had genetic material removed, rearranged, mutagenized or added, such as knock out. Computed

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Project description:Reactive oxygen species (ROS) play a prominent role in signal transduction and cellular homeostasis in plants. However, imbalances between generation and elimination of ROS can give rise to oxidative stress in growing cells. Because ROS are important to cell growth, ROS modulation could be responsive to natural or human-mediated selection pressure in plants. To study the evolution of oxidative stress related genes in a single plant cell, we conducted comparative expression profiling analyses of the elongated seed trichomes (‘‘fibers’’) of cotton (Gossypium), using a phylogenetic approach. We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes in progenitor diploid species revealed significant up-regulation of ROS scavenging and potential signaling processes in domesticated G. arboreum. Similarly, in two independently domesticated allopolyploid species (G. barbadense and G. hirsutum) antioxidant genes were substantially up-regulated in comparison to antecedent wild forms. In contrast, analyses of three wild allopolyploid species indicate that genomic merger and ancient allopolyploid formation had no significant influences on regulation of ROS related genes. Remarkably, many of the ROS-related processes diagnosed as possible targets of selection were shared among diploid and allopolyploid cultigens, but involved different sets of antioxidant genes. Our data suggests that parallel human selection for enhanced fiber growth in several geographically widely dispersed species of domesticated cotton resulted in similar and overlapping metabolic transformations of the manner in which cellular redox levels have become modulated. We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes was studied for domesticated G. arboreum and two independently domesticated allopolyploid species (G. barbadense and G. hirsutum). These were compared to three wild allopolyploid species. Three biological replicates were performed.

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The evolution of spinable cotton fiber entailed prolonged development and a novel metabolism

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The evolution of spinnable cotton fiber entailed prolonged development and a novel metabolism.

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