Samakovli, D. | bioRxiv Science

bioRxiv2020

The interplay of HSP90s with YDA regulates main body axis formation during early embryogenesis in Arabidopsis

The YODA kinase (YDA) pathway is intimately associated with the control of Arabidopsis thaliana embryo development but little is known regarding its regulators. Using genetic analysis, HEAT SHOCK PROTEINS 90 (HSP90s) emerge as potent regulators of YDA in the process of embryo development and patterning. This study is focused on the characterization and quantification of early embryonal traits of single and double hsp90 and yda mutants. The mutant analysis was supported by expression analyses of cell-specific WUSCHEL-RELATED HOMEOBOX 2 (WOX2) and WOX8 genes during early embryonic development. Chromatin immunoprecipitation assays corroborated the involvement of YDA and HSP90s in the epigenetic control of chromatin remodeling during early embryogenesis. Genetic interactions among HSP90s and members of the YDA signaling pathway affected the development of both embryo proper and suspensor. Impaired function of HSP90s or YDA had an impact on the spatiotemporal expression of WOX8 and WOX2 suggesting their essential role in cell fate determination and interference with auxin distribution. Hence, the interplay between HSP90s and YDA signaling cascade mediates the epigenetic control regulating the transcriptional networks shaping early embryo development.

plant biology↗

bioRxiv2018

Environment and HSP90 modulate MAPK stomatal developmental pathway

Stomatal ontogenesis is a key element of plant adaptation aiming to control photosynthetic efficiency and water management under fluctuating environments 1,2,3. Development of stomata is guided by endogenous and environmental cues and is tightly coupled to overall plant growth 1,2,3. YODA signaling pathway is essential to stomatal lineage specification4,5,6 since it regulates the activities of transcription factors such as SPEECHLESS (SPCH)7,8,9,10. Heat-shock proteins 90 (HSP90s) are evolutionarily conserved molecular chaperones implicated in a broad range of signalling pathways being integrated in interaction networks with client proteins11,12,13,14. Herein, based on genetic, molecular, biochemical, and cell biological evidence we report that heat-stress conditions affect phosphorylation and deactivation of SPCH and modulate stomatal density. We show that genetic and physical interactions between HSP90s and YODA control stomatal patterning, distribution and morphology. We provide solid evidence that HSP90s play a major role in transducing the heat-stress response since they act upstream and downstream of YODA signalling, regulate the activity and nucleocytoplasmic distribution of MAPKs, and the activation of SPCH. Thus, HSPs control the stomatal development both under normal temperature and acute heat-stress conditions. Our results demonstrate that HSP90s couple stomatal formation and patterning to environmental cues providing an adaptive mechanism of heat-stress tolerance response and stomatal formation in Arabidopsis.

plant biology↗