Biochemical and Expression Analyses Revealed the Involvement of Proanthocyanidins and/or Their Derivatives in Fiber Pigmentation of Gossypium stocksii.

Yuqing Wu,Liping Ke,Yujie Sun,Dongliang Yu,Jun Mei,Diandian Zhang,Hongli Zheng,Yuqiang Sun

doi:10.3390/ijms23021008

Yuqing Wu, Liping Ke + Show 6 more

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https://doi.org/10.3390/ijms23021008

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Abstract

The wild cotton species Gossypium stocksii produces a brown fiber that provides a valuable resource for the color improvement of naturally colored cotton (NCC) fiber. However, the biochemical basis and molecular mechanism of its fiber pigmentation remain unclear. Herein, we analyzed the dynamics of proanthocyanidins (PAs) accumulation in developing the fiber of G. stocksii, which suggested a similar role of PAs and/or their derivatives in the fiber coloration of G. stocksii. In addition, comparative transcriptomics analyses revealed that the PA biosynthetic genes were expressed at higher levels and for a longer period in developing fibers of G. stocksii than G. arboreum (white fiber), and the transcription factors, such as TT8, possibly played crucial regulatory roles in regulating the PA branch genes. Moreover, we found that the anthocyanidin reductase (ANR) was expressed at a higher level than the leucoanthocyanidin reductases (LARs) and significantly upregulated during fiber elongation, suggesting a major role of ANR in PA synthesis in G. stocksii fiber. In summary, this work revealed the accumulation of PAs and the expression enhancement of PA biosynthetic genes in developing fibers of G. stocksii. We believe this work will help our understanding of the molecular mechanisms of cotton fiber coloration and further promote the future breeding of novel NCCs.

Highlights

Cotton fiber is the most important fabric material globally, with almost all the industrially used cotton coming from white cotton fiber (WCF)
Slight brown fuzz could be found around 12 days after anthesis (DPA), apparent brown fiber was only observed around 18 DPA, and the coloration continuously darkened until the boll opening period (Figure 1)
In this work, according to the microstructures of the developing fibers, growth of primary cell wall (PCW) was observed at 6 to 12 DPA, but the secondary cell wall (SCW) was only observed from 15 DPA and thickened in subsequent periods, indicating that the stage of transition from fiber elongation to SCW biosynthesis was around 12–15 DPA in G. stocksii

Summary

Introduction

Cotton fiber is the most important fabric material globally, with almost all the industrially used cotton coming from white cotton fiber (WCF). With the rising concern of environmental issues and the higher life quality of human beings, the interest in naturally colored cotton (NCC, G. hirsutum) fiber has continuously increased in the last decade. The utilization of NCC fiber in the fabric would minimize textile processing and extensively reduce the generation of toxic chemical wastes [1]. Poor fiber quality and dull colors have greatly hindered the large-scale utilization of NCC fiber [2]. Understanding of the pigmentation in NCC fiber has been largely promoted in the last two decades. The currently available NCCs mainly produce green or brown fibers

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