Project description:Purpose: The goal of this experiment was to use RNA-seq to compare the two commercial cotton species Gossypium hirsutum and Gossypium barbadense and determine what transcripts may account for the better fiber quality in the latter. Methods: RNA was extracted from Gossypium barbadense or Gossypium hirsutum fibers at 10, 15, 18, 21, and 28 days post anthesis. Paired-end, 100-bp RNA-seq was performed on an Illumina HiSeq2000 and the reads were mapped to the Gossypium raimondii genome at www.phytozome.net and non-homologous contig assemblies from Gossypium arboreum. Results from RNA-seq were combined with non-targeted metabolomics. Results: Approximately 38,000 transcripts were expressed (RPKM>2) in each fiber type and approximately 2,000 of these transcripts were differentially expressed in a cross-species comparison at each timepoint. Enriched Gene Ontology biological processes in differentially expressed transcripts suggested that Gh fibers were more stressed. Conclusions: Both metabolomic and transcriptomic data suggest that better mechanisms for managing reactive oxygen species contribute to the increased fiber length in Gossypium barbadense. This appears to result from enhanced ascorbate biosynthesis via gulono-1,4-lactone oxidase and ascorbate recycling via dehydroascorbate reductase.
Project description:Purpose: The goal of this experiment was to use RNA-seq to compare the two commercial cotton species Gossypium hirsutum and Gossypium barbadense and determine what transcripts may account for the better fiber quality in the latter. Methods: RNA was extracted from Gossypium barbadense or Gossypium hirsutum fibers at 10, 15, 18, 21, and 28 days post anthesis. Paired-end, 100-bp RNA-seq was performed on an Illumina HiSeq2000 and the reads were mapped to the Gossypium raimondii genome at www.phytozome.net and non-homologous contig assemblies from Gossypium arboreum. Results from RNA-seq were combined with non-targeted metabolomics. Results: Approximately 38,000 transcripts were expressed (RPKM>2) in each fiber type and approximately 2,000 of these transcripts were differentially expressed in a cross-species comparison at each timepoint. Enriched Gene Ontology biological processes in differentially expressed transcripts suggested that Gh fibers were more stressed. Conclusions: Both metabolomic and transcriptomic data suggest that better mechanisms for managing reactive oxygen species contribute to the increased fiber length in Gossypium barbadense. This appears to result from enhanced ascorbate biosynthesis via gulono-1,4-lactone oxidase and ascorbate recycling via dehydroascorbate reductase. See Bioproject PRJNA263926 and SRA accession SRP049330 for study design and raw sequencing data and Bioproject PRJNA269608 and TSA accession GBYK00000000 for Gossypium arboreum assembled contig sequences used for transcriptome mapping - Cotton fiber mRNA from 10,15,18,21 and 28 day post anthesis fiber from either Gossypium hirusutm or Gossypium barbadense was sequenced and differential gene expression analysis was conducted between species for each timepoint and between adjacent timepoints. Each timepoint was representative of fiber from 9 individual plants processed as 3 biological replicate pools (material from 3 individual plants per pool).
Project description:Most wild and semi-wild species of the genus Gossypium are exhibit photoperiod-sensitive flowering. The wild germplasm cotton is a valuable source of genes for genetic improvement of modern cotton cultivars. A bi-parental cotton population segregating for photoperiodic flowering was developed by crossing a photoperiod insensitive irradiation mutant line with its pre-mutagenesis photoperiodic wild-type G. darwinii Watt genotype. Individuals from the F2 and F3 generations were grown with their parental lines and F1 hybrid progeny in the long day and short night summer condition (natural day-length) of Uzbekistan to evaluate photoperiod sensitivity, i.e., flowering-time during the seasons 2008-2009. Through genotyping the individuals of this bi-parental population segregating for flowering-time, linkage maps were constructed using 212 simple-sequence repeat (SSR) and three cleaved amplified polymorphic sequence (CAPS) markers. Six QTLs directly associated with flowering-time and photoperiodic flowering were discovered in the F2 population, whereas eight QTLs were identified in the F3 population. Two QTLs controlling photoperiodic flowering and duration of flowering were common in both populations. In silico annotations of the flanking DNA sequences of mapped SSRs from sequenced cotton (G. hirsutum L.) genome database has identified several potential 'candidate' genes that are known to be associated with regulation of flowering characteristics of plants. The outcome of this research will expand our understanding of the genetic and molecular mechanisms of photoperiodic flowering. Identified markers should be useful for marker-assisted selection in cotton breeding to improve early flowering characteristics.