QTL Mapping for Fibre Quality Traits in Cotton: Genetic Architecture, Molecular Markers and Breeding Applications

Abstract

Cotton (Gossypium spp.) is one of the world’s most important fibre crops, and fibre quality is a major

determinant of its economic value and suitability for textile processing. Important fibre quality character-
istics include fibre length, fibre strength, micronaire, fibre elongation, fibre uniformity and fibre maturity.

These traits are quantitative in nature and are controlled by multiple genes interacting with environmental
factors. Quantitative trait locus (QTL) mapping has therefore become an important approach for dissecting
the genetic basis of fibre quality and identifying genomic regions associated with desirable phenotypes.
Advances in cotton genome sequencing, molecular marker development and high-density genetic mapping
have substantially increased the resolution and reliability of QTL identification. Numerous QTLs have been

detected for fibre length, strength, fineness, elongation and uniformity, with several genomic regions repeat-
edly detected across populations and environments. Recent studies have further combined QTL mapping

with genome-wide association studies (GWAS), transcriptomics, meta-analysis and candidate-gene analysis
to identify stable loci and genes controlling fibre development. Marker-assisted selection (MAS), genomic

selection and genome editing provide opportunities for translating these discoveries into breeding pro-
grammes. This review discusses the genetic basis of cotton fibre quality, QTL mapping strategies, important

fibre-quality QTLs, molecular markers, QTL × environment interactions, candidate genes and applications in
molecular breeding. Integration of QTL information with high-throughput genomics and precision breeding
is expected to accelerate the development of cotton cultivars possessing superior fibre quality together with
high yield and environmental adaptability.