Abstract
BackgroundSea island cotton (Gossypium barbadense) has markedly superior high quality fibers, which plays an important role in the textile industry and acts as a donor for upland cotton (G. hirsutum) fiber quality improvement. The genetic characteristics analysis and the identification of key genes will be helpful to understand the mechanism of fiber development and breeding utilization in sea island cotton.ResultsIn this study, 279 sea island cotton accessions were collected from different origins for genotyping and phenotyping fiber quality traits. A set of 6303 high quality single nucleotide polymorphisms (SNPs) were obtained by high-density CottonSNP80K array. The population characteristics showed that the sea island cotton accessions had wide genetic diversity and were clustered into three groups, with Group1 closely related to Menoufi, an original sea island cotton landrace, and Group2 and Group3 related to widely introduced accessions from Egypt, USA and Former Soviet Union. Further, we used 249 accessions and evaluated five fiber quality traits under normal and salt environments over 2 years. Except for fiber uniformity (FU), fiber length (FL) and fiber elongation (FE) were significantly decreased in salt conditions, while fiber strength (FS) and fiber micronaire (MIC) were increased. Based on 6303 SNPs and genome-wide association study (GWAS) analysis, a total of 34 stable quantitative trait loci (QTLs) were identified for the five fiber quality traits with 25 detected simultaneously under normal and salt environments. Gene Ontology (GO) analysis indicated that candidate genes in the 25 overlapped QTLs were enriched mostly in “cellular and biological process”. In addition, “xylem development” and “response to hormone” pathways were also found. Haplotype analyses found that GB_A03G0335 encoding an E3 ubiquitin-protein ligase in QTL TM6004 had SNP variation (A/C) in gene region, was significantly correlated with FL, FS, FU, and FE, implying a crucial role in fiber quality.ConclusionsThe present study provides a foundation for genetic diversity of sea island cotton accessions and will contribute to fiber quality improvement in breeding practice.
Highlights
Sea island cotton (Gossypium barbadense) has markedly superior high quality fibers, which plays an important role in the textile industry and acts as a donor for upland cotton (G. hirsutum) fiber quality improvement
In this study, 279 sea island cotton accessions were collected from different origins, and genotyping for population structure and phenotyping for fiber qualities in different soil environments over 2 years were systematically investigated
These results showed that the CottonSNP80K array could genotype sea island cotton accessions with good efficiency and accuracy
Summary
Sea island cotton (Gossypium barbadense) has markedly superior high quality fibers, which plays an important role in the textile industry and acts as a donor for upland cotton (G. hirsutum) fiber quality improvement. Upland cotton (G. hirsutum) and sea island cotton (G. barbadense) are the two main cultivated tetraploid species accounting for more than 97% of the total cotton production [1]. Upland cotton produces high yields with moderate fiber quality, whereas sea island cotton has exceptionally high quality fibers [2]. As the textile industry rapidly develops and the demand for textile products continues to diversify, the improvement of cotton fiber quality is more and more important [3]. The introgression of chromosome segments can effectively combine the yield advantage of upland cotton with the quality improvement from sea island cotton [4]. It is of great significance to explore the elite chromosome segments in G. barbadense for improving cotton fiber quality in breeding
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