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

Jute ( Corchorus spp.) is an important industrial bast fibre crop valued for its lignocellulosic fibres, yet the molecular basis of fibre lignification remains unexplored. Laccase (EC 1.10.3.2) is a key enzyme catalysing the final steps of lignin polymerisation. A genome-wide analysis of white jute ( Corchorus capsularis ) identified 34 putative laccase genes ( CcaLAC s), phylogenetically grouped into six clades. Expression profiling revealed predominant expression in phloem tissue (17 genes), followed by leaf (9) and xylem/root tissues (4). Several CcaLAC s showed progressive upregulation from early growth to harvest stages. Homology with Arabidopsis laccases highlighted candidate genes involved in lignification, which were further supported by transcriptomic and qRT-PCR analyses. Notably, key CcaLAC s showed significantly reduced expression in dlpf , a low-lignin white jute mutant. CcaLAC expression was also responsive to abiotic stresses, including abscisic acid and copper. MicroRNA target prediction identified Ath-miR397a and Ath-miR397b as potential regulators of multiple CcaLAC s. Structural and subcellular analyses revealed conserved motifs, transmembrane domains, and diverse cellular localization. Gene ontology analysis linked CcaLAC s to lignin and phenylpropanoid biosynthesis. Among them, CcaLAC28 and CcaLAC32 emerged as strong candidates regulating phloem fibre lignification, providing promising targets for developing low-lignin jute varieties for industrial applications.