Comprehensive analysis of the laccase gene family in cucumber highlights its potential roles in development and stress responses

A genome-wide analysis identified 34 laccase genes in cucumber and highlighted three, CsLAC22, CsLAC29 and CsLAC31, as candidates for involvement in responses to both salt and heat stress. The study combined genome searches, structural and evolutionary comparisons, promoter analysis, predicted protein interactions, transcript profiling and quantitative real-time PCR. Researchers described the findings as a resource for future functional studies rather than evidence that any individual gene improves cucumber stress tolerance.

Plant laccase genes are involved in lignin biosynthesis, cell-wall formation, growth and development, and responses to biotic and abiotic stress, but the laccase gene family had not previously been characterized systematically in cucumber. Using hidden Markov model searches followed by conserved-domain validation, the researchers identified 34 cucumber laccase genes, designated CsLAC genes. Their corresponding proteins were classified into six subfamilies, with members within the same subfamily generally showing similar motif compositions and exon–intron structures.

The 34 CsLAC genes were unevenly distributed across cucumber’s seven chromosomes, with chromosome 1 containing the largest number of members. Intragenomic analysis identified one tandem duplication pair and eight putative whole-genome or segmental duplication pairs. The researchers also detected 27 syntenic gene pairs between cucumber and Arabidopsis thaliana.

Ka/Ks ratios were below 1 for all analyzed duplicated gene pairs, a result interpreted as indicating that purifying selection was the predominant evolutionary force acting on the cucumber laccase family. Promoter analysis revealed numerous cis-acting elements associated with light responses, hormone signaling, stress responses and plant development. These regulatory sequences provide a framework for examining how individual family members may respond to different signals, although the promoter analysis itself did not establish gene function.

Protein–protein interaction predictions identified CsLAC23, CsLAC19 and CsLAC21 as relatively highly connected nodes in the inferred network. These are computational relationships that require experimental testing, but they narrow the set of genes that may be useful targets for future studies. Expression profiling showed that individual CsLAC genes have distinct patterns of transcript accumulation.

Some genes showed broad expression, whereas others were preferential for particular tissues, developmental stages or treatment conditions. The researchers also recorded different temporal responses among family members during heat, salt and pathogen treatments. These results indicate that the laccase family is not represented by a single uniform response pattern across the tested tissues, stages and stresses.

To assess the transcriptome-derived patterns, the investigators used quantitative real-time PCR on eight selected CsLAC genes, with six genes examined under each stress treatment. The measured temporal expression trends were generally consistent with the profiles identified through transcriptome analysis. The agreement supports the reproducibility of the reported expression observations, but it does not determine the precise functions of the encoded proteins or show that altered expression causes greater stress tolerance.

Among the genes examined, CsLAC22, CsLAC29 and CsLAC31 were identified as candidates that may participate in responses to both heat and salt stress. Their designation reflects their observed expression-associated patterns, not a demonstrated mechanism or an intervention tested in cucumber. Functional studies would be needed to determine whether these genes affect stress responses directly, whether their activity is influenced by the regulatory elements identified in their promoters, and how their products interact with other cellular components.

Overall, the study provides a genome-wide characterization of cucumber laccase genes, documenting their distribution, duplication history, promoter features, predicted interaction relationships and expression patterns across tissues, developmental stages and stress treatments. Because the evidence is based on computational analysis, expression profiling and targeted validation, the study does not yet establish the causal contribution of any CsLAC gene to cucumber stress tolerance.

Subject of Research: Genome-wide characterization of cucumber laccase genes and their expression during development and stress.

Article Title: Comprehensive analysis of the laccase gene family in cucumber highlights its potential roles in development and stress responses

Article References: Zhang, Z., Wang, W., Zhao, Q., Wu, R., & Zhao, J. (2026). Comprehensive analysis of the laccase gene family in cucumber highlights its potential roles in development and stress responses. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09858-z

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09858-z

Keywords: cucumber, laccase genes, plant biology, salt stress, heat stress, gene duplication, gene expression, promoter analysis, protein interactions, cell-wall biology, Comprehensive, analysis