Heteroblasty is a developmental trajectory event where plants have rapid ontogenetic changes across multiple traits, as exemplified by plants switching from distinct juvenile to adult leaves. Heteroblastic leaves enable plants to adapt to environmental heterogeneity, serving as a prime example of adaptive evolution. Previous studies have uncovered some of the underlying differences of heteroblasty in aquatic seed plants, however, the mechanism behind sterile-fertile leaf dimorphy remains relatively unexplored in aquatic ferns.

To understand the molecule mechanism regulating the heteroblastic leaves in Ceratopteris chingii, research teams from Wuhan Botanical Garden, Hubei Ecology Polytechnic College, and Ghent University studied the transcriptome datasets between sporophylls and trophophylls using PacBio full-length sequencing and Illumina RNA-seq.

Comparative analysis detected differentially expressed genes involved in reproduction and cell wall composition pathways. Of these, expansion genes account for most of the significantly enriched Gene Ontology(GO) terms.

Through the reconstruction of phylogeny of expansion genes, four different phylogenetic groups of expansion genes were distinguished in 19 plant species, ranging from green algae to seed plants. By means of coexpression analysis, expression behavior has largely diverged both within and between species.

In a word, specific regulatory interactions and accompanying expression patterns of expansion genes played important roles in heteroblastic leaves of Ceratopteris chingii.

The research was funded by the Strategic Priority Research Program of Chinese Academy of Sciences, the National Natural Science Foundation of China. The results have been published in BMC Biology entitled “Expression divergence of expansin genes drive the heteroblasty in Ceratopteris chingii”.