Genome-wide identification of multifunctional laccase gene family in cotton (Gossypium spp.); expression and biochemical analysis during fiber development.

Vimal Kumar Balasubramanian,Sandi Win Thu,Krishan Mohan Rai,Mei Mei Hii,Venugopal Mendu

doi:10.1038/srep34309

Vimal Kumar Balasubramanian, Sandi Win Thu + Show 3 more

Open Access

https://doi.org/10.1038/srep34309

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Abstract

The single-celled cotton fibers, produced from seed coat epidermal cells are the largest natural source of textile fibers. The economic value of cotton fiber lies in its length and quality. The multifunctional laccase enzymes play important roles in cell elongation, lignification and pigmentation in plants and could play crucial role in cotton fiber quality. Genome-wide analysis of cultivated allotetraploid (G. hirsutum) and its progenitor diploid (G. arboreum and G. raimondii) cotton species identified 84, 44 and 46 laccase genes, respectively. Analysis of chromosomal location, phylogeny, conserved domain and physical properties showed highly conserved nature of laccases across three cotton species. Gene expression, enzymatic activity and biochemical analysis of developing cotton fibers was performed using G. arboreum species. Of the total 44, 40 laccases showed expression during different stages of fiber development. The higher enzymatic activity of laccases correlated with higher lignin content at 25 DPA (Days Post Anthesis). Further, analysis of cotton fiber phenolic compounds showed an overall decrease at 25 DPA indicating possible incorporation of these substrates into lignin polymer during secondary cell wall biosynthesis. Overall data indicate significant roles of laccases in cotton fiber development, and presents an excellent opportunity for manipulation of fiber development and quality.

Highlights

Cotton fiber is a single-celled seed trichome, developed from seed coat epidermal cells through four distinct, yet overlapping stages: 1) initiation (−3 to 5 DPA, days post anthesis); 2) elongation (5–25 DPA); 3) secondary cell wall (SCW) deposition (25–40 DPA) and 4) maturation (40–60 DPA)
The G. raimondii and G. hirsutum laccase proteins were named according to their phylogenetic closeness to G. arboreum laccases (Supplementary Table S4)
The multifunctional laccase enzymes are involved in cell elongation[19], pigmentation[15] and SCW biosynthesis[13,33] in Arabidopsis

Summary

Introduction

Cotton fiber is a single-celled seed trichome, developed from seed coat epidermal cells through four distinct, yet overlapping stages: 1) initiation (−3 to 5 DPA, days post anthesis); 2) elongation (5–25 DPA); 3) secondary cell wall (SCW) deposition (25–40 DPA) and 4) maturation (40–60 DPA). The plant laccases are involved in lignin[13,14] and flavonoid[15] biosynthesis while the microbial laccases are primarily involved in lignin breakdown[16] Phenolic acids such as, benzoic (vanillic and sinapic acid) and cinnamic acid derivatives (p-coumaric, ferulic and caffeic acids) are part of lignin and flavonoid biosynthetic pathways[7]. Benzoic (vanillic and sinapic acid) and cinnamic acid derivatives (p-coumaric, ferulic and caffeic acids) are part of lignin and flavonoid biosynthetic pathways[7] These phenolic acids play an important role in cell elongation in plants[17,18]. Due to the presence large number of genes (84) in tetraploid G. hirsutum species and lack of fiber production in G. raimondii, the gene expression, enzyme activity and biochemical analysis (lignin and soluble/wall bound phenolic acids) were performed using G. arboreum fibers

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