Allele and transcriptome mining in Gossypium hirsutum reveals variation in candidate genes at genetic loci affecting cotton fiber quality and textile flammability.

Abstract

Background: Breeding valuable traits in crop plants requires identifying diverse alleles in the germplasm that are likely to affect desirable characteristics. The genetic diversity of historic cultivars of cotton is a reservoir of potentially important genes for crop improvement and genetic research. Diversity in the characteristics of harvested cotton fibers affects their suitability for end-use applications. Candidate loci and genes have been identified that affect the length, strength, and maturity of cotton fibers which affect the quality and value of the yarn, thread and textile. Natural genetic mechanisms in the plant may also affect the flammability of the produced textiles.

Results: Here we show that a combination of allele mining and transcriptome analysis can identify candidate genes for cotton fiber traits including strength and perhaps flammability. We found novel DNA variants in fiber-expressed gene families in 132 newly sequenced cotton varieties and identified genes with genotype-specific RNA expression.

Conclusions: Among these, we identified novel variation in DNA sequence and RNA expression in genes at major QTL qD04-ELO-WLIM (JGI-Gohir.D04G160000), qA13-MIC (Gohir.A13G157500), qA07-STR (Gohir.A07G191600), supported the candidacy of qD11-UHML-KRP6 (Gohir.D11G197900) and qD13-STR (Gohir.D13G17450), and identified an additional A03-WLIM transcription factor gene (Gohir.A03G182100) and several RNA expression variant candidates of potential flammability genes that may be useful for plant biologists and cotton breeders. Candidate genes for traits like flame resistance that are likely due to the combination of many small effect QTL can benefit from this multi-mining approach. We provide an annotated variant call format (vcf) file with variations at 24,996 loci that are predicted to affect 10,418 cotton fiber genes in the historic breeding germplasm.