Genetic variation of dynamic fiber elongation and developmental quantitative trait locus mapping of fiber length in upland cotton (Gossypium hirsutum L.)

Jianjiang Ma,Dan Li,Jinfa Zhang,Man Wu,Xingli Li,Shuxun Yu,Guoyuan Liu,Yanhui Geng,Xinshan Zang,Qifeng Ma,Wenfeng Pei,Jiwen Yu

doi:10.1186/s12864-018-5309-2

Abstract

BackgroundIn upland cotton (Gossypium hirsutum L.), genotypes with the same mature fiber length (FL) might possess different genes and exhibit differential expression of genes related to fiber elongation at different fiber developmental stages. However, there is a lack of information on the genetic variation influencing fiber length and its quantitative trait loci (QTLs) during the fiber elongation stage. In this study, a subset of upland cotton accessions was selected based on a previous GWAS conducted in China and grown in multiple environments to determine the dynamic fiber length at 10, 15, 20, and 25 days post-anthesis (DPA) and maturity. The germplasm lines were genotyped with the Cotton 63 K Illumina single-nucleotide polymorphism (SNP) array for GWAS.ResultsA total of 25, 38, 57, 89 and 88 SNPs showed significant correlations with fiber length at 10, 15, 20 and 25 DPA and maturity, respectively. In addition, 60 more promising SNPs were detected in at least two tests and two FL developmental time points, and 20 SNPs were located within the confidence intervals of QTLs identified in previous studies. The fastest fiber-length growth rates were obtained at 10 to 15 DPA in 69 upland cotton lines and at 15 to 20 DPA in 14 upland cotton accessions, and 10 SNPs showed significant correlations with the fiber-length growth rate. A combined transcriptome and qRT-PCR analysis revealed that two genes (D10G1008 and D13G2037) showed differential expression between two long-fiber genotypes and two short-fiber genotypes.ConclusionsThis study provides important new insights into the genetic basis of the time-dependent fiber-length trait and reveals candidate SNPs and genes for improving fiber length in upland cotton.

Highlights

In upland cotton (Gossypium hirsutum L.), genotypes with the same mature fiber length (FL) might possess different genes and exhibit differential expression of genes related to fiber elongation at different fiber developmental stages
Phenotypic variations in dynamic FL among upland cotton accessions Extensive phenotypic variation in FL at five fiber developmental time points (10, 15, 20, and 25 days post-anthesis (DPA), and maturity) was observed in this association panel of 83 upland cotton accessions tested in Anyang over three consecutive years from 2014 to 2016 (Table 1 and Additional file 2: Figure S1)
A further partition of variances showed that the broad sense heritability (H2) values of FL at 10, 15, 20, and 25 DPA and maturity were 49.14, 47.56, 60.63, 71.06, and 92.45%, respectively (Table 2), suggesting that the H2 increased as the fibers elongated and grew after 10–15 DPA and that the FL at maturity was highly inherited

Summary

Introduction

In upland cotton (Gossypium hirsutum L.), genotypes with the same mature fiber length (FL) might possess different genes and exhibit differential expression of genes related to fiber elongation at different fiber developmental stages. A subset of upland cotton accessions was selected based on a previous GWAS conducted in China and grown in multiple environments to determine the dynamic fiber length at 10, 15, 20, and 25 days post-anthesis (DPA) and maturity. Upland cotton (G. hirsutum L.) accounts for more than 95% of cotton production worldwide [3]. Another cultivated tetraploid species, referred to as Egyptian, Pima or Sea-Island cotton (G. barbadense L.), exhibits superior extra-long fibers [2]. The elongation of fibers occurs after initiation and lasts until 25–30 days post anthesis (DPA), which determines the ultimate fiber

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