Molecular Regulation of Cotton Fiber Development: A Review

Abstract

Cotton (Gossypium spp.) is an economically important natural fiber crop. The quality of cotton fiber has a substantial effect on the quality of cotton textiles. The identification of cotton fiber development-related genes and exploration of their biological functions will not only enhance our understanding of the elongation and developmental mechanisms of cotton fibers but also provide insights that could aid the cultivation of new cotton varieties with improved fiber quality. Cotton fibers are single cells that have been differentiated from the ovule epidermis and serve as a model system for research on single-cell differentiation, growth, and fiber production. Genes and fiber formation mechanisms are examined in this review to shed new light on how important phytohormones, transcription factors, proteins, and genes linked to fiber development work together. Plant hormones, which occur in low quantities, play a critically important role in regulating cotton fiber development. Here, we review recent research that has greatly contributed to our understanding of the roles of different phytohormones in fiber development and regulation. We discuss the mechanisms by which phytohormones regulate the initiation and elongation of fiber cells in cotton, as well as the identification of genes involved in hormone biosynthetic and signaling pathways that regulate the initiation, elongation, and development of cotton fibers.

Keywords: cotton (Gossypium spp.); fiber development; molecular mechanism; phytohormones; transcription factors.

Figure 1

Role of TFs in different stages of cotton fiber development. (A,B) Boll and fiber development. (C) Fiber developmental stages include initiation, elongation, secondary wall biosynthesis, and maturation. (B) Scanning electron microscope (SEM) images from -2 DPA (ovule fiber initiation) to 35 DPA (fiber development completion). SEM scale = 100 μm. (D) Key TFs are involved in the regulation of cotton fiber development.

Figure 2

Model representation of how PAG1 and BR regulate fiber elongation. PAG1 catabolism activates endogenous BRs, which stimulate the expression of enzymes involved in very-long-chain fatty acid (VLCFA) biosynthesis, such as KCSs. VLCFAs promote fiber elongation by activating the expression of ETH biosynthesis genes (ACOs). Both ETH and BRs promote fiber elongation by stimulating the expression of cell wall and cytoskeleton-related genes. BRs also affect fiber elongation and BR-GhSK13 fiber development in cotton.

Figure 3

Hormones affecting fiber development, ovule growth, and boll retention. A schematic depiction of a cotton plant’s secondary stem, fruiting stem, and boll (left) and an enlarged view of a fiber-bearing ovule (right) are shown. Hormones that promote boll maintenance, ovule growth, and fiber initiation or growth (left to right) are shown at the top with arrows; inhibitory hormones are shown at the bottom with blocked blunted lines.

Figure 4

A diagram summarizing the roles of multiple phytohormones in cotton fiber initiation. A schematic model showing the roles of various phytohormones during cotton fiber development. Arrows show promoting actions, and blocked blunted lines show inhibitory actions. Yellow lines indicate the inactivation pathway, green lines indicate the synthetic pathway, black lines indicate the regulatory pathway, and red lines indicate suppression.

Figure 5

A schematic model of how cotton fiber cells grow, with Ca²⁺, K⁺, and H⁺ channels and ion efflux. Ca²⁺, K⁺, and H⁺ channels and efflux fluctuations are observed in both the tip and the base of the elongating fiber cells that were treated with H₂O₂.