Stomata, highly specialized structures that evolved on the aerial surfaces of plants, play a crucial role in regulating hydration, mitigating the effects of abiotic stress. Stomatal lineage development involves a series of coordinated events, such as initiation, stem cell proliferation, and cell fate determination, ultimately leading to the differentiation of guard cells. While core transcriptional regulators and signaling pathways controlling stomatal cell division and fate determination have been characterized over the past twenty years, the molecular mechanisms linking stomatal development to dynamic environmental cues remain poorly understood. Therefore, stomatal development is considered an active and compelling frontier in plant biology research. On the one hand, this review aims to provide an understanding of the molecular networks governing stomatal ontogenesis, which relies on the activation and function of the transcription factors SPEECHLESS (SPCH), MUTE, and FAMA; the EPF–TMM and ERECTA receptor systems; and downstream MAPK signaling. On the other hand, it synthesizes current discoveries of how hormonal signaling pathways regulate stomatal development in response to environmental changes. As the climate crisis intensifies, the understanding of the complex interplay between stress stimuli and key factors regulating stomatal development may reveal key mechanisms that enhance plant resilience under adverse environmental conditions.

WD40 repeat proteins (WDRs) are present in all eukaryotes and include members that are implicated in numerous cellular activities. They act as scaffold proteins and thus as molecular “hubs” for protein–protein interactions, which mediate the assembly of multifunctional complexes that regulate key developmental processes in Arabidopsis thaliana, such as flowering time, hormonal signaling, and stress responses. Despite their importance, many aspects of their putative functions have not been elucidated yet. Here, we show that the late-flowering phenotype of the anthesis promoting factor 1 (aprf1) mutants is temperature-dependent and can be suppressed when plants are grown under mild heat stress conditions. To gain further insight into the mechanism of APRF1 function, we employed a co-immunoprecipitation (Co-IP) approach to identify its interaction partners. We provide the first interactome of APRF1, which includes proteins that are localized in several subcellular compartments and are implicated in diverse cellular functions. The dual nucleocytoplasmic localization of ARRF1, which was validated through the interaction of APRF1 with HEAT SHOCK PROTEIN 1 (HSP90.1) in the nucleus and with HSP90.2 in the cytoplasm, indicates a dynamic and versatile involvement of APRF1 in multiple biological processes. The specific interaction of APRF1 with the chaperon HSP90.1 in the nucleus expands our knowledge regarding the epigenetic regulation of flowering time in A. thaliana and further suggests the existence of a delicate thermoregulated mechanism during anthesis.

In plants, the transition from heterotrophic to autotrophic growth is a critical developmental shift, tightly coupled to the establishment of photosynthesis. This process demands a precise interplay between the nucleus and chloroplasts, with communication schemes providing essential checkpoints to synchronize gene expression during seedling greening and establishment. While light response and photomorphogenesis are known to rely on transcriptional networks, recent evidence highlights a key role for alternative pre-mRNA splicing in facilitating plant adaptation to new light regimes, thereby enhancing transcriptome diversity. LEFKOTHEA, a dual-localized nuclear and chloroplast protein, has emerged as a potential integrator of these processes; it mediates the splicing of both chloroplast group II introns and nuclear introns via interactions with spliceosomal proteins. Here, we demonstrate that LEFKOTHEA is an active component of early light response signaling, regulating gene expression both transcriptionally and post-transcriptionally. Transcriptomic analysis reveals that LEFKOTHEA shapes the transcriptome both quantitatively and qualitatively by modulating alternative splicing, a mechanism essential for plant plasticity and adaptation. Furthermore, we show that the dynamic subcellular localization of LEFKOTHEA underpins its role in establishing a nucleus–chloroplast communication network that guides plant development.