Abstract
BackgroundCotton fiber length is an important quality attribute to the textile industry and longer fibers can be more efficiently spun into yarns to produce superior fabrics. There is typically a negative correlation between yield and fiber quality traits such as length. An understanding of the regulatory mechanisms controlling fiber length can potentially provide a valuable tool for cotton breeders to improve fiber length while maintaining high yields. The cotton (Gossypium hirsutum L.) fiber mutation Ligon lintless-2 is controlled by a single dominant gene (Li2) that results in significantly shorter fibers than a wild-type. In a near-isogenic state with a wild-type cotton line, Li2 is a model system with which to study fiber elongation.ResultsTwo near-isogenic lines of Ligon lintless-2 (Li2) cotton, one mutant and one wild-type, were developed through five generations of backcrosses (BC5). An F2 population was developed from a cross between the two Li2 near-isogenic lines and used to develop a linkage map of the Li2 locus on chromosome 18. Five simple sequence repeat (SSR) markers were closely mapped around the Li2 locus region with two of the markers flanking the Li2 locus at 0.87 and 0.52 centimorgan. No apparent differences in fiber initiation and early fiber elongation were observed between the mutant ovules and the wild-type ones. Gene expression profiling using microarrays suggested roles of reactive oxygen species (ROS) homeostasis and cytokinin regulation in the Li2 mutant phenotype. Microarray gene expression data led to successful identification of an EST-SSR marker (NAU3991) that displayed complete linkage to the Li2 locus.ConclusionsIn the field of cotton genomics, we report the first successful conversion of gene expression data into an SSR marker that is associated with a genomic region harboring a gene responsible for a fiber trait. The EST-derived SSR marker NAU3991 displayed complete linkage to the Li2 locus on chromosome 18 and resided in a gene with similarity to a putative plectin-related protein. The complete linkage suggests that this expressed sequence may be the Li2 gene.
Highlights
Cotton fiber length is an important quality attribute to the textile industry and longer fibers can be more efficiently spun into yarns to produce superior fabrics
Mutant Texas marker-1 (TM-1) cotton plants containing the Li2 gene were crossed with the Upland cotton variety DP5690 and F1 progeny were backcrossed for five generations (BC5) by SSD to DP5690 which served as the recurrent parent in each backcross
The heterozygous line was removed from the greenhouse and both the mutant and WT population were reduced to 72 individual plants each to achieve the randomized complete block design of the experiment
Summary
Cotton fiber length is an important quality attribute to the textile industry and longer fibers can be more efficiently spun into yarns to produce superior fabrics. 25% of the ovule epidermal cells differentiate into fiber cells during the initiation stage of cotton fiber development and subsequently undergo a transition stage that usually begins from 12 to 16 DPA in field conditions and depending on environmental factors such as lower temperatures that are shown to delay the onset of the transition stage [6]. The final stage of fiber development is maturation that ceases from 40 to 60 DPA depending on environment and genotype [9]. At this time the cotton bolls crack and open, exposing the seed fibers to external ambient conditions causing them to desiccate and take on the fluffy appearance normally associated with cotton fibers
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