The study found that distinct MYB proteins can either promote or suppress pigment accumulation by regulating key genes in the flavonoid pathway and interacting with known pigment-related proteins. These findings provide new insight into the molecular basis of naturally colored cotton and offer potential genetic targets for improving brown cotton fiber quality while maintaining its environmentally friendly value for the textile industry.
Naturally colored cotton is valued because it can reduce the need for dyeing and may offer advantages such as environmental friendliness, antibacterial properties, and ultraviolet protection. Brown cotton is the most common type of naturally colored cotton, and its pigmentation mainly comes from proanthocyanidins, a class of flavonoid compounds. However, compared with white cotton, brown cotton often shows lower yield and poorer fiber quality, which limits its broader industrial use. Previous studies have identified several key enzymes and transcription factors involved in pigment formation, including GhLAR, GhANR, GhDFR, GhTT2-3A, and GhMYB113. Yet many candidate regulators detected by transcriptomic, proteomic, and metabolomic analyses still lacked direct functional validation, making it necessary to clarify how multiple transcription factors jointly regulate pigment biosynthesis in cotton fibers.
A study (DOI:10.48130/seedbio-0026-0010) published in Seed Biology on 17 April 2026 by Wenliang Xu’s team, Central China Normal University, reports that cotton proanthocyanidin biosynthesis is governed by a balanced regulatory system in which MYB activators and repressors work together to control pigment deposition.
The researchers integrated existing multi-omics datasets from brown and white cotton fibers with known flavonoid-related MYB proteins from 34 plant species. This screening first produced 145 MYB candidates potentially linked to anthocyanin or proanthocyanidin biosynthesis, which were then narrowed to 27 stronger candidates through comparative and phylogenetic analyses. Expression profiling in brown and white cotton fibers at different developmental stages further highlighted 12 MYB genes that were differentially expressed and showed correlation with the known pigment activators GhTT2-3A and/or GhMYB113. The team then used transient expression assays in tobacco leaves to test whether these candidates could alter pigment accumulation. Among the 12 MYBs, two promoted pigment deposition, eight suppressed it, and two showed no detectable effect under the tested conditions. For deeper functional validation, three representative MYBs were selected: GhMYB3_A08, GhMYB5_A11, and GhMYB308_A01. Subcellular localization confirmed that all three proteins were located in the nucleus, consistent with their roles as transcription factors. Cotton callus transformation showed that overexpression of GhMYB3_A08 enhanced proanthocyanidin accumulation and upregulated the pathway genes GhLAR, GhDFR, and GhANR. In contrast, overexpression of GhMYB5_A11 or GhMYB308_A01 reduced pigment accumulation and downregulated these same biosynthetic genes. Dual-luciferase assays further showed that GhMYB3_A08 strengthened GhMYB113-mediated promoter activation, while GhMYB5_A11 and GhMYB308_A01 antagonized this activation. Protein interaction assays demonstrated that these MYBs could form complexes with GhTT2-3A and/or GhMYB113, with some also interacting with GhbHLH130D, suggesting that pigment regulation depends on both transcriptional control and protein–protein interaction networks.
Overall, the study reveals that brown cotton pigmentation is not controlled by a single activator but by a multilayered MYB regulatory network. By distinguishing activators from repressors and validating their molecular functions, the research expands understanding of proanthocyanidin biosynthesis in cotton and provides candidate genes for future molecular breeding. These results may support efforts to develop naturally colored cotton varieties with improved fiber traits, helping align cotton production with more sustainable textile manufacturing.
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References
DOI
10.48130/seedbio-0026-0010
Original Source URL
https://doi.org/10.48130/seedbio-0026-0010
Funding information
This work was supported by the Key Research and Development Program of Xinjiang Uygur Autonomous Region (2024B02006-2) and National Natural Science Foundation of China (Grant No. 32372104).
About Seed Biology
Seed Biology (e-ISSN 2834-5495) is published by Maximum Academic Press in partnership with Yazhou Bay Seed Laboratory. Seed Biology is an open access, online-only journal focusing on research related to all aspects of the biology of seeds, including but not limited to: evolution of seeds; developmental processes including sporogenesis and gametogenesis, pollination and fertilization; apomixis and artificial seed technologies; regulation and manipulation of seed yield; nutrition and health-related quality of the endosperm, cotyledons, and the seed coat; seed dormancy and germination; seed interactions with the biotic and abiotic environment; and roles of seeds in fruit development. Seed biology publishes a wide range of research approaches, such as omics, genetics, biotechnology, genome editing, cellular and molecular biology, physiology, and environmental biology. Seed Biology publishes high-quality original research, reviews, perspectives, and opinions in open access mode, promoting fast submission, review, and dissemination freely to the global research community.