Genome-wide Identification of the Laccase Gene Family in White Jute (Corchorus capsularis): Potential Targets for Lignin Engineering in Bast Fiber

Abstract

The industrial bast fibre crop jute (Corchorussp.) is known for its long lignocellulosic multi-utility fibres. Information on jute fibre lignification is limited, and many enzymes in the jute lignin pathway are not well documented. One such enzyme is laccase (EC 1.10.3.2), involved in the final polymerization step of lignification. A whole-genome search of white jute (Corchorus capsularis) revealed 34 putative laccase (CcaLAC) genes. Phylogenetic analysis categorized these genes into six groups, with 17 predominantly expressed in phloem tissue, 9 in leaf, and 4 in xylem and roots. A steady increase in gene expression, from plantlets to crop harvest, was observed for severalCcaLACs. Some were selected for further analysis based on homology withArabidopsislignin pathway-modifying laccases (AtLACs). Transcriptomics data confirmed their expression in phloem tissues, with some showing significantly lower expression indlpf, a low-lignin fibre-containing white jute mutant. Changes inCcaLACexpression were observed under abiotic stresses like ABA hormone and copper heavy metal. Target sites for Ath-miR397a and Ath-miR397b were predicted in 11 and 9CcaLACs, respectively, suggesting possible post-transcriptional modification via microRNA. Subcellular localization showedCcaLACs in multiple plant cell compartments. Protein structure predictions revealed up to 10 motifs in CcaLACs, with 18 containing transmembrane helices. Overall,CcaLAC28andCcaLAC32are likely involved in the lignification process of phloem (bast) in white jute. Modifying these genes could enhance our understanding of lignification and potentially lead to the development of low-lignin jute fibres, meeting high industrial demands globally.HighlightsJute is known for its long lignocellulosic fibres.34 putative laccase genes were identified in white jute.17 laccase genes are mainly expressed in phloem tissue.CcaLAC28andCcaLAC32are key candidates for lignification.Laccase genes showed changes under abiotic stresses.Key MessageIdentified 34 laccase genes in white jute, key for understanding and engineering lignification in fibres.