Genome-wide identification of multifunctional laccase gene family in Eucalyptus grandis: potential targets for lignin engineering and stress tolerance

Abstract

Key message A survey of the Eucalyptus grandis genome revealed the presence of 54 laccase genes. Their tissue-specific and stress-induced expression patterns suggest a role in lignification and adaptation to abiotic stresses. Abstract Laccases are multicopper oxidases that play important roles in the oxidation of monolignols during lignin biosynthesis and are reported to be functionally involved in plant development and stress responses. In this study, a genome-wide survey of the Eucalyptus grandis genome revealed the presence of 54 putative LAC genes (referred as EgrLAC), which were assigned to six different phylogenetic groups. Among them, 17 were predicted to be potential targets of miR397, a negative regulator of lignin biosynthesis. Based on different RNA-Seq datasets, distinct organ/tissue expression patterns of the identified EgrLAC genes were ascertained. The vast majority, however, showed enriched expression in the vascular tissues of roots and stems. Additional expression profiling of selected EgrLAC genes revealed differential expression in response to oxidative and osmotic stresses, suggesting a role in abiotic stress responses. Parallel promoter analysis of EgrLAC4, a close homologue to the Arabidopsis lignin biosynthesis-related gene AtLAC17, revealed a vascular expression pattern, mostly associated with the phloem. Overall, our data point to an involvement of the identified EgrLAC genes in lignification and in Eucalyptus adaptation to abiotic stresses.

Transcriptome Analysis Reveals Genes of Flooding-Tolerant and Flooding-Sensitive Rapeseeds Differentially Respond to Flooding at the Germination Stage

“…Protease-associated (PA) RING/U-box zinc finger family proteins are involved in protein coding, protein–protein interaction, and trafficking of soluble proteins through subcellular compartments [ 90 ]. SKS5 belongs to a gene family ( SKU5-similar ) related structurally to the multiple-copper oxidases, ascorbate oxidase, and laccase, which playing vital roles in lignin biosynthesis, plant development, and stress responses [ 91 ]. What is more, SKU5 and its homologs was reported to be involved in directional root growth by participating in cell wall expansion and synthesis [ 92 , 93 ].…”

Plant miR397 and its functions

“…In rice, at least fifteen of the 30 LACs were predicted as the potential targets of miR397, and several of them (such as OsLAC3, OsLAC6, OsLAC7, and OsLAC19) were confirmed in the Indica line O. nivara by degradome analysis (Swetha et al 2018). In Eucalyptus grandis, 17 LAC genes were predicted as the target genes of miR397, among which LAC1, LAC4, LAC10, LAC11, LAC12 and LAC20 were highly expressed in xylem and involved in the biosynthesis of xylem lignin and maintaining mechanical toughness of stems (Arcuri et al 2020). In pears, 27 LAC genes identified from genomic sequences were potential target genes of PbrmiR397a (Xue et al 2019).…”

Transcriptome Sequence Reveals Candidate Genes Involving in the Post-Harvest Hardening of Trifoliate Yam Dioscorea dumetorum

“…Laccase has been recognized in the lignification process through the oxidation of lignin precursors. Indeed, Arcuri et al [26] demonstrated involvement of LACCASE genes in lignification as a response to adaptation to abiotic stresses in Eucalyptus.…”