Quantitative Trait Locus Analysis and Identification of Candidate Genes for Micronaire in an Interspecific Backcross Inbred Line Population of Gossypium hirsutum × Gossypium barbadense.

Wenfeng Pei,Jiwen Yu,Quanjia Chen,Hai Lei,Yu Zhang,Wenkui Wang,Jikun Song,Luyao Wu,Jianjiang Ma,Xuefei Gao,Yanying Qu,Haijun Hu,Haiyong Zhu,Chengcheng Hu,Bing Jia,Jinfa Zhang,Man Wu,Qin Qin

doi:10.3389/fpls.2021.763016

Abstract

Cotton is the most important fiber crop and provides indispensable natural fibers for the textile industry. Micronaire (MIC) is determined by fiber fineness and maturity and is an important component of fiber quality. Gossypium barbadense L. possesses long, strong and fine fibers, while upland cotton (Gossypium hirsutum L.) is high yielding with high MIC and widely cultivated worldwide. To identify quantitative trait loci (QTLs) and candidate genes for MIC in G. barbadense, a population of 250 backcross inbred lines (BILs), developed from an interspecific cross of upland cotton CRI36 × Egyptian cotton (G. barbadense) Hai7124, was evaluated in 9 replicated field tests. Based on a high-density genetic map with 7709 genotyping-by-sequencing (GBS)-based single-nucleotide polymorphism (SNP) markers, 25 MIC QTLs were identified, including 12 previously described QTLs and 13 new QTLs. Importantly, two stable MIC QTLs (qMIC-D03-2 on D03 and qMIC-D08-1 on D08) were identified. Of a total of 338 genes identified within the two QTL regions, eight candidate genes with differential expression between TM-1 and Hai7124 were identified. Our research provides valuable information for improving MIC in cotton breeding.

Highlights

Cotton (Gossypium spp.) is an important cash crop species worldwide, providing an essential natural resource for the textile industry
An interspecific backcross inbred lines (BILs) population comprising 250 BC1F7 lines was developed from a cross between Egyptian cotton (G. barbadense) Hai7124 and Chinese G. hirsutum CRI36
The values of skewness and kurtosis in each environment showed that MIC followed a normal distribution in the BIL population (Supplementary Figure 1 and Table 1)

Summary

Introduction

Cotton (Gossypium spp.) is an important cash crop species worldwide, providing an essential natural resource for the textile industry. Extra-long staple, Pima, Egyptian, or Sea Island cotton (Gossypium barbadense L.) have excellent fiber quality with long, strong and fine fibers, but their low yield and requirements for warm and dry weather conditions limit their cultivation area The goal of cotton breeding in China has shifted to improving fiber quality (including fiber length, strength, and micronaire (MIC)], in addition to high yield (Fang et al, 2017). There have been an increasing number of studies on improving cotton fiber quality traits through interspecific hybridization, especially G. hirsutum × G. barbadense (Zhang et al, 2014; Wang et al, 2020)

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Conclusion