• The cotton fibre serves as a valuable experimental system to study cell wall synthesis in plants, but our understanding of the genetic regulation of this process during fibre development remains ...limited.
• We performed a genome-wide association study (GWAS) and identified 28 genetic loci associated with fibre quality in allotetraploid cotton. To investigate the regulatory roles of these loci, we sequenced fibre transcriptomes of 251 cotton accessions and identified 15 330 expression quantitative trait loci (eQTL).
• Analysis of local eQTL and GWAS data prioritised 13 likely causal genes for differential fibre quality in a transcriptome-wide association study (TWAS). Characterisation of distal eQTL revealed unequal genetic regulation patterns between two subgenomes, highlighted by an eQTL hotspot (Hot216) that established a genome-wide genetic network regulating the expression of 962 genes. The primary regulatory role of Hot216, and specifically the gene encoding a KIP-related protein, was found to be the transcriptional regulation of genes responsible for cell wall synthesis, which contributes to fibre length by modulating the developmental transition from rapid cell elongation to secondary cell wall synthesis.
• This study uncovered the genetic regulation of fibre-cell development and revealed the molecular basis of the temporal modulation of secondary cell wall synthesis during plant cell elongation.
Summary
Cotton fibre is a unicellular seed trichome, and lint fibre initials per seed as a factor determines fibre yield. However, the mechanisms controlling fibre initiation from ovule epidermis are ...not understood well enough. Here, with single‐cell RNA sequencing (scRNA‐seq), a total of 14 535 cells were identified from cotton ovule outer integument of Xu142_LF line at four developmental stages (1.5, 1, 0.5 days before anthesis and the day of anthesis). Three major cell types, fibre, non‐fibre epidermis and outer pigment layer were identified and then verified by RNA in situ hybridization. A comparative analysis on scRNA‐seq data between Xu142 and its fibreless mutant Xu142 fl further confirmed fibre cluster definition. The developmental trajectory of fibre cell was reconstructed, and fibre cell was identified differentiated at 1 day before anthesis. Gene regulatory networks at four stages revealed the spatiotemporal pattern of core transcription factors, and MYB25‐like and HOX3 were demonstrated played key roles as commanders in fibre differentiation and tip‐biased diffuse growth respectively. A model for early development of a single fibre cell was proposed here, which sheds light on further deciphering mechanism of plant trichome and the improvement of cotton fibre yield.
With scRNA‐seq, cotton fibre cell was identified differentiated at −1 DPA. It further refines the spatiotemporal patterns of two command genes, MYB25‐like and HOX3, who determine fibre differentiation and tip‐biased diffuse growth respectively.
Summary
Cotton fibre is the most important source for natural textiles. The secondary cell walls (SCWs) of mature cotton fibres contain the highest proportion of cellulose content (> 90%) in any ...plant. The onset and progression of SCW cellulose synthesis need to be tightly controlled to balance fibre elongation and cell wall deposition. However, regulatory mechanisms that control cellulose synthesis during cotton fibre growth remain elusive.
Here, we conducted genetic and functional analyses demonstrating that the R2R3‐MYB GhMYB7 controls cotton fibre cellulose synthesis.
Overexpression of GhMYB7 in cotton sped up SCW cellulose biosynthesis in fibre cells, and led to shorter fibres with thicker walls. By contrast, RNA interference (RNAi) silencing of GhMYB7 delayed fibre SCW cellulose synthesis and resulted in elongated fibres with thinner walls. Furthermore, we demonstrated that GhMYB7 regulated cotton fibre SCW cellulose synthases by directly binding to three distinct cis‐elements in the respective GhCesA4, GhCesA7 and GhCesA8 promoters. We found that this regulatory mechanism of cellulose synthesis was ‘hi‐jacked’ also by other GhMYBs.
Together, our findings uncover a hitherto‐unknown mechanism that cotton fibre employs to regulate SCW cellulose synthesis. Our results also provide a strategy for genetic improvement of SCW thickness of cotton fibre.
Arsenic contamination has attracted worldwide concerns, owing to its toxicity and severe threat to human and environment. It is urgent to develop efficient adsorbents to remove arsenic pollutants. ...Within this paper, both pristine MIL-88A(Fe) and MIL-88A(Fe) decorated on cotton fibers were successfully fabricated using an eco-friendly method. The pristine MIL-88A(Fe) displayed outstanding adsorption performances towards four selected arsenic pollutants, in which the adsorption capacities toward As(III), As(V), ROX and ASA were 126.5, 164.0, 261.4 and 427.5 mg g−1, respectively. Additionally, MIL-88A(Fe) exhibited excellent removal efficiencies in a wide pH range and with the presence of different co-existing ions. It was proposed that the coordinative interactions of As–O–Fe between arsenic pollutants and MIL-88A(Fe) contributed to the superior adsorption performances. Furthermore, two MIL-88A(Fe)/cotton fibers composites were synthesized by both post synthesis (MC-1) and in-situ synthesis (MC-2), which demonstrated identically outstanding adsorption activities toward four selected arsenic pollutants. MC-1 and MC-2 enhanced the stability and reusability of MIL-88A(Fe), which was challenging issues of pristine MIL-88A(Fe) powder. Additionally, the fixed-bed column packed by MC-1 or MC-2 can continuously eliminate arsenic pollutants from the water flow. This work provided a new possibility of metal-organic frameworks to accomplish potentially large-scale application to purify the arsenic-contaminated water.
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•MIL-88A(Fe) exhibits excellent adsorption abilities toward different arsenics.•MIL-88A(Fe) decorated on cotton fibers maintains outstanding adsorption activities.•The combination of MIL-88A(Fe) and cotton fibers improves its stability.•MIL-88A(Fe) decorated on cotton fibers achieves good reusability.•MIL-88A(Fe) decorated on cotton fibers exhibits potential large-scale application.
Summary
Secondary cell wall (SCW) biosynthesis is an important stage of the cotton fibre development, and its transcriptional regulation is poorly understood. We selected the Gossypium hirsutum GDSL ...(GhGDSL) lipase/hydrolase gene (CotAD_74480), which is expressed during SCW biosynthesis (19 through to 25 days postanthesis; DPA), for study. T1‐transgenic cotton lines expressing the β‐glucuronidase (gus) reporter under the control of a 1026‐bp promoter fragment of GhGDSL (PGhGDSL) showed 19 DPA stage‐specific increase in GUS expression. 5′ deletion indicated that the 194‐bp fragment between –788 and –594 relative to the transcription start site was essential for this stage‐specific expression. Site‐directed mutagenesis of eight transcription factor binding sites within PGhGDSL demonstrated that the MYB1AT motif (AAACCA) at –603/–598 was critical for the 19 DPA‐specific reporter gene expressions. Yeast one‐hybrid (Y1H) analysis identified nine proteins, including GhMYB1 (CotAD_64719) that bound to the PGhGDSL promoter. Further, Y1H experiments using the 5′ promoter deletions and individually mutated promoter motifs indicated that GhMYB1 interacted with PGhGDSL at MYB1AT sequence. GhMYB1 was expressed specifically in fibre from 19 DPA, overlapping with the sharp rise in GhGDSL expression, indicating that it could regulate GhGDSL during fibre development. Analysis of genes co‐expressed with GhMYB1 showed that it potentially regulates a number of other 19–25 DPA‐specific genes in networks including those functioning in the cell wall and precursor synthesis, but not the major polysaccharide and protein components of the fibre SCW. GhGDSL and its promoter are therefore potential tools for the improvement of cotton fibre quality traits.
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•Cotton fiber modified with succinic anhydride is beneficial to cell adhesion.•The deletion of PAS_chr2-1_0773 gene promotes the formation of biofilm.•The carrier and cell surface ...properties determine the immobilization effect.•The fermentation performance was improved by optimizing the carrier and strain.
Compared with the traditional suspension fermentation, immobilised biofilm fermentation has advantages of strong resistance, high yield and continuous fermentation and is conducive to improving the industrial fermentation methods. The formation of a biofilm on correct supports is critical to immobilised fermentation. In this study, Pichia pastoris was used to understand and control the modification of surface properties of supports and cells. Following deletion of gene PAS_chr2-1_0773, in P. pastoris △0773, the cell-surface negative charge density decreased and hydrophobicity improved, which was conducive to adhesion. Therefore, according to the changing trend of cell surface properties, cotton fibre was used with succinic anhydride (SA) to modify the carrier for changing the surface properties for efficient conduction of immobilised fermentation. In the fermentation process, the adhesion between the modified cotton fibre and yeast was better than that between an unmodified cotton fibre and yeast, and the additive amount increased by ∼25 %. The enzyme activity of the △0773-cotton-SA fermentation system reached 302.7 U/mL, which was 39.6 % higher than that of the original fermentation system. Therefore, this study provides a guide for significant improvement of immobilised fermentation of fungi.
Transcription factors play key roles in plant development through their interaction with cis-elements and/or other transcription factors. A HD-Zip IV family transcription factor, Gossypium barbadense ...Meristem Layer 1 (GbML1) has been identified and characterized here. GbML1 specifically bound to the L1 box and the promoters of GbML1 and GbRDL1. GbML1 physically interacted with a key regulator of cotton fibre development, GbMYB25. Truncated and point mutation assays indicated the START–SAD domain was required for the binding to the C terminal domain (CTD) of GbMYB25. GbML1 overexpression in Arabidopsis increased the number of trichomes on stems and leaves and increased the accumulation of anthocyanin in leaves. Taken together, the L1 box binding protein, GbML1 was identified as the first partner for GbMYB25 and the role of START domain was discovered to be a protein binding domain in plants. Our findings will help the improvement of cotton fibre production and the understanding of the key role of HD-Zip family and MYB family in plants.
Electrical communication between an enzyme and an electrode is one of the most important factors in determining the performance of biofuel cells. Here, we introduce a glucose oxidase-coated metallic ...cotton fiber-based hybrid biofuel cell with efficient electrical communication between the anodic enzyme and the conductive support. Gold nanoparticles are layer-by-layer assembled with small organic linkers onto cotton fibers to form metallic cotton fibers with extremely high conductivity (>2.1×10
S cm
), and are used as an enzyme-free cathode as well as a conductive support for the enzymatic anode. For preparation of the anode, the glucose oxidase is sequentially layer-by-layer-assembled with the same linkers onto the metallic cotton fibers. The resulting biofuel cells exhibit a remarkable power density of 3.7 mW cm
, significantly outperforming conventional biofuel cells. Our strategy to promote charge transfer through electrodes can provide an important tool to improve the performance of biofuel cells.
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