Heteroblasty, a pivotal developmental event in plants, involves rapid ontogenetic changes in multiple traits, notably observed in the transition from juvenile to adult leaves. This phenomenon allows plants to adapt to environmental variations and stands as a noteworthy example of adaptive evolution. While previous studies have shed light on heteroblasty in aquatic seed plants, the mechanisms governing sterile-fertile leaf dimorphy in aquatic ferns have remained largely unexplored.
In a collaborative effort, researchers from the Wuhan Botanical Garden of the Chinese Academy of Sciences (CAS), Hubei Ecology Polytechnic College, and Ghent University delved into the molecular intricacies of heteroblastic leaves in Ceratopteris chingii. The team utilized PacBio full-length sequencing and Illumina RNA-seq to analyze transcriptome datasets between sporophylls and trophophylls, unraveling key insights into the underlying molecular mechanisms.
Their findings, published in BMC Biology under the title “Expression divergence of expansin genes drive the heteroblasty in Ceratopteris chingii,” unveiled differentially expressed genes associated with reproduction and cell wall composition pathways. Notably, expansion genes emerged as predominant players, constituting the majority of significantly enriched Gene Ontology terms.
The researchers further conducted a thorough reconstruction of the expansion gene phylogeny, identifying four distinct phylogenetic groups across 19 plant species, spanning from green algae to seed plants. Co-expression analysis revealed highly divergent expression behaviors both within and between species, indicating the critical role of specific regulatory interactions and associated expression patterns of expansion genes in the heteroblastic leaves of Ceratopteris chingii.
This groundbreaking study not only expands our understanding of heteroblasty in aquatic ferns but also highlights the intricate molecular machinery orchestrating this developmental trajectory. By shedding light on the role of expansion genes, the research contributes valuable insights into the adaptive evolution of plants in response to environmental heterogeneity, paving the way for further exploration in the field of plant developmental biology.