Genome-wide analysis identifies six mangrove bZIP genes induced by multiple stresses

A genome-wide study of Avicennia marina identified 105 basic leucine zipper, or bZIP, genes and highlighted six family members whose expression increased across multiple plant tissues following exposure to cold, heat, salt, drought and abscisic acid. Quantitative real-time PCR validated consistent upregulation of AmbZIP4, AmbZIP36, AmbZIP78, AmbZIP84, AmbZIP90 and AmbZIP94 in roots, shoots and leaves, providing candidate genes for further investigation of abiotic stress responses in the mangrove. The research characterized the bZIP gene family across the plant’s 26 chromosomes.

The 105 identified genes encode predominantly hydrophilic proteins and were assigned to nine phylogenetic clades. Two clades associated with stress-related groups were particularly well represented: group A contained 23 genes and group D contained 19. Three conserved motifs, designated 1, 2 and 13, defined the characteristic bZIP signature.

The analysis also detected 76 segmentally duplicated gene pairs. Their ratios of nonsynonymous to synonymous substitutions, expressed as Ka/Ks, were below 1, consistent with strong purifying selection. These findings describe the organization and evolutionary pattern of the gene family but do not by themselves demonstrate the functions of individual genes under environmental stress.

Promoter analysis found 2,133 cis-regulatory elements across the bZIP genes. Hormone-associated elements accounted for 37% of the total, elements linked to light accounted for 33%, and stress-associated elements represented 25%, indicating that the family’s regulatory regions contain signals associated with several biological and environmental responses. A separate analysis predicted 648 microRNAs capable of targeting 97 AmbZIP genes, with ath-miR166 identified as the most abundant.

These are sequence-based regulatory predictions, so they indicate possible regulatory relationships that require experimental testing rather than confirmed mechanisms of stress resistance. The six prioritized genes showed consistent increases in roots, shoots and leaves under the five tested treatments, yet the reported results do not establish that any of them causes enhanced stress tolerance, changes in plant survival or improved ecosystem performance. Functional studies would be needed to determine how the proteins act and whether their induced expression contributes causally to a response.

Subject of Research: Genomic and expression analysis of bZIP genes in Avicennia marina under abiotic stress treatments.

Article Title: Comprehensive analysis of basic leucine zipper (bZIP) genes in Avicennia marina: genomic insights and expression profiling reveal their roles in abiotic stress response mechanisms

Article References: Anwar, M., Huang, M., Lin, R., Du, Y., Rizwan, H. M., Wang, W., & Zhao, Y. (2026). Comprehensive analysis of basic leucine zipper (bZIP) genes in Avicennia marina: genomic insights and expression profiling reveal their roles in abiotic stress response mechanisms. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09536-0

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09536-0

Keywords: Avicennia marina, bZIP genes, mangrove, abiotic stress, gene expression, quantitative PCR, promoter analysis, microRNA regulation, phylogenetics, Comprehensive, analysis, basic