Insights into cryptochrome modulation of ABA signaling to mediate dormancy regulation in Marchantia polymorpha.

The acquisition of dormancy capabilities has enabled plants to survive in adverse terrestrial environmental conditions. Dormancy accumulation and release is coupled with light signaling, which is well studied in Arabidopsis, but it is unclear in the distant nonvascular relative. We study the characteristics and function on dormancy regulation of a blue light receptor cryptochrome in Marchantia polymorpha (MpCRY). Here, we identified MpCRY via bioinformatics and mutant complement analysis. The biochemical characteristics were assessed by multiple protein-binding assays. The function of MpCRY in gemma dormancy was clarified by overexpression and mutation of MpCRY, and its mechanism was analyzed via RNA sequencing and quantitative PCR analyses associated with hormone treatment. We found that the unique MpCRY protein in M. polymorpha undergoes both blue light-promoted interaction with itself (self-interaction) and blue light-dependent phosphorylation. MpCRY has the specific characteristics of blue light-induced nuclear localization and degradation. We further demonstrated that MpCRY transcriptionally represses abscisic acid (ABA) signaling-related gene expression to suppress gemma dormancy, which is dependent on blue light signaling. Our findings indicate that MpCRY possesses specific biochemical and molecular characteristics, and modulates ABA signaling under blue light conditions to regulate gemma dormancy in M. polymorpha.

Time-course transcriptome analysis reveals regulation of Arabidopsis seed dormancy by the transcription factors WOX11/12.

The induction of seed dormancy and its release involve a finely regulated genetic program controlled by various environmental and developmental cues that are critical for plant survival and population expansion. Light plays a key role in seed dormancy and germination, but the molecular mechanisms underlying the control of dormancy are unclear. In the present study, high-resolution temporal RNA-seq in Arabidopsis identified WOX11 as encoding a hub transcription factor during the seed dormancy induction and release stages. This gene might have evolved from gymnosperms and expanded in angiosperms with highly conserved expression patterns in seeds. WOX11 and its homolog WOX12 were highly expressed from 2 d after pollination, and mRNA abundance was greatly increased during the seed dormancy induction and release stages. Further, we found that WOX11 plays a role in the regulation of seed dormancy downstream of phytochrome B (PHYB)-mediated red-light signaling during the induction stage, indicating that WOX11/12 are newly identified components of red-light signaling transduction. Taken together, our results suggest that WOX11/12-mediated PHYB signaling regulates seed dormancy in Arabidopsis, and provide insights into the developmental regulation and evolutionary adaptation of plants to changes in the light environment.