Genetic variations in plant architecture traits in cotton (Gossypium hirsutum) revealed by a genome-wide association study

Plant architecture traits influence crop yield. An understanding of the genetic basis of cotton plant architecture traits is beneficial for identifying favorable alleles and functional genes and breeding elite cultivars. We collected 121 cotton accessions including 100 brown-fiber and 21 white-fiber accessions, genotyped them by whole-genome resequencing, and phenotyped them in multiple environments. This genome-wide association study (GWAS) identified 11 quantitative trait loci (QTL) for two plant architecture traits: plant height and fruit spur branch number. Negative-effect alleles were enriched in the elite cultivars. Based on these QTL, gene annotation information, and published QTL, candidate genes and natural genetic variations in four QTL were identified. Ghir_D02G017510 and Ghir_D02G017600 were identified as candidate genes for qD02-FSBN-1, and a premature start codon gain variation was found in Ghir_D02G017510. Ghir_A12G026570, the candidate gene of qA12-FSBN-2, belongs to the pectin lyase-like superfamily, and a significantly associated SNP, A12_105366045 (T/C), in this gene represents an amino acid change. The QTL, candidate genes, and associated natural variations in this study are expected to lay a foundation for studying functional genes and developing breeding programs for desirable architecture in brown-fiber cotton. Keywords: Brown-fiber cotton, Plant architecture traits, GWAS, QTL, Genetic variatio

Identification of QTL for Fiber Quality and Yield Traits Using Two Immortalized Backcross Populations in Upland Cotton.

Two immortalized backcross populations (DHBCF1s and JMBCF1s) were developed using a recombinant inbred line (RIL) population crossed with the two parents DH962 and Jimian5 (as the males), respectively. The fiber quality and yield component traits of the two backcross populations were phenotyped at four environments (two locations, two years). One hundred seventy-eight quantitative trait loci (QTL) were detected including 76 for fiber qualities and 102 for yield components, explaining 4.08-17.79% of the phenotypic variation (PV). Among the 178 QTL, 22 stable QTL were detected in more than one environment or population. A stable QTL, qFL-c10-1, was detected in the previous F2 population, a RIL population in 3 environments and the current two BCF1 populations in this study, explaining 5.79-37.09% of the PV. Additionally, 117 and 110 main-effect QTL (M-QTL) and 47 and 191 digenic epistatic QTL (E-QTL) were detected in the DHBCF1s and JMBCF1s populations, respectively. The effect of digenic epistasis played a more important role on lint percentage, fiber length and fiber strength. These results obtained in the present study provided more resources to obtain stable QTL, confirming the authenticity and reliability of the QTL for molecular marker-assisted selection breeding and QTL cloning

Additional file 3: Table S3. of Genomic heterozygosity and hybrid breakdown in cotton (Gossypium): different traits, different effects

MHIs in (E3) F2 population. (XLS 14 kb

Additional file 2: Table S2. of Genomic heterozygosity and hybrid breakdown in cotton (Gossypium): different traits, different effects

MHIs in (3E) F2 population. (XLS 26 kb

Additional file 4: Table S4. of Genomic heterozygosity and hybrid breakdown in cotton (Gossypium): different traits, different effects

The QTL for studied traits searched from the cotton QTL Database. (XLS 25 kb

QTL Mapping for Fiber and Yield Traits in Upland Cotton under Multiple Environments.

A population of 178 recombinant inbred lines (RILs) was developed using a single seed descendant from a cross between G. hirsutum. acc DH962 and G. hirsutum. cv Jimian5, was used to construct a genetic map and to map QTL for fiber and yield traits. A total of 644 polymorphic loci were used to construct a final genetic map, containing 616 loci and spanning 2016.44 cM, with an average of 3.27 cM between adjacent markers. Statistical analysis revealed that segregation distortion in the intraspecific population was more serious than that in the interspecific population. The RIL population and the two parents were phenotyped under 8 environments (two locations, six years), revealing a total of 134 QTL, including 64 for fiber qualities and 70 for yield components, independently detected in seven environments, explaining 4.40-15.28% of phenotypic variation (PV). Among the 134 QTL, 9 common QTL were detected in more than one environment, and 22 QTL and 19 new QTL were detected in combined analysis (E9). A total of 26 QTL hotspot regions were observed on 13 chromosomes and 2 larger linkage groups, and some QTL clusters related to fiber qualities or yield components were also observed. The results obtained in the present study suggested that to map accurate QTL in crops with larger plant types, such as cotton, phenotyping under multiple environments is necessary to effectively apply the obtained results in molecular marker-assisted selection breeding and QTL cloning

Two-Dimensional Boron Sheets as Metal-Free Catalysts for Hydrogen Evolution Reaction

Current metal-free catalysts for hydrogen evolution reaction (HER) are mainly carbon-based. In this work, HER catalytic activity on two-dimensional (2D) boron sheets (α and β₁₂) are explored using periodic density functional theory. Using the binding free energy of H (Δ<i>G</i>_H*) as the descriptor, we found that both α and β₁₂ sheets present superior activity, with Δ<i>G</i>_H* being close to zero. It is expected that 2D boron sheets would be a promising metal-free catalyst in the electrolysis of water and may offer novel thoughts for the design of new catalysts for other reactions

In Situ STEM Determination of the Atomic Structure and Reconstruction Mechanism of the TiO₂ (001) (1 × 4) Surface

The widely studied anatase TiO₂ (001) surface usually shows a (1 × 4) reconstruction, which may directly influence its physical and chemical properties. Although various atomic models are proposed, the debates regarding the models and the formation mechanism of such reconstruction remain until now due to the lack of direct experimental evidence at the atomic level. Herein, we report the atomic-scale determination of the atomic structure and the reconstruction mechanism of the TiO₂ (001) (1 × 4) surface by in situ spherical aberration corrected scanning transmission electron microscopy (STEM) at elevated temperature. The atomic features of the reconstructed surface are unambiguously identified in our experiments, providing a solid evidence to verify the ad-molecule model, which was predicted by the calculations 15 years ago. Furthermore, the mysterious reconstruction route is revealed by our real time STEM images, which involves a new metaphase of the (001) surface. These results are expected to help resolve current dispute concerning the reconstruction models and understand the true performances of the anatase TiO₂ (001) surface