During the growth and development of organisms, they need to adjust the development process at any time to cope with different exogenous or endogenous stimuli. Due to their immovable nature, plants need to respond to exogenous environmental stimuli at any time. Intracellular signaling pathways mediate the occurrence from stimulation to cell response. How the same signaling pathway achieves differential regulation of cell development processes is a fundamental problem in biological growth and development. Some signaling molecules affect the specificity or activity of kinases or cell fate determinants through differences in their subcellular localization and nucleoplasm distribution, and thus affect cell fate decisions. This concept has been well developed and proven in the field of animals, but little is known in plant development.
On May 4, 2022, the team of Professor Dong Juan of the Wackersman Institute of Rutgers University published a research paper entitled “Dichotomy of the BSL phosphatase signaling spatially regulates MAPK components in stomatal fate determination” in Nature Communications magazine. The molecular mechanism of mode arabidopsis thaliana affecting stomatal development is revealed through differential regulation of signaling pathways mediated by the protein phosphatase BSL family.
The BSL family consists of four genes: BSU1 and BSL1, BSL2, and BSL3. BSL acts as a protein phosphatase and is involved in both the plant’s response to the hormone canola steroid (BR) and the plant’s immune response to biological stress. Previously in the study of the plant response hormone canola steroid (BR), it was believed that the BSL family represented by BSU1 has redundant functions, acting on the downstream of cytoplasmic kinase BSK1, dephosphorylation and promoting the degradation of cytoplasmic kinase BIN2, thereby promoting the expression of BR response transcription factors and initiating the plant’s response to BR. Through detailed genetic analysis of the four gene mutants, Professor Dong Juan’s team found that all four genes are involved in the developmental regulation of plant stomata. Through the phenotype and genetic analysis of the combination of two mutants, three mutants and four mutants of different gene mutations, it is found that the four genes may play different functions in the process of stomatal development. Further studies confirmed that the four proteins of the BSL family have different subcellular localizations, suggesting that they may act on different specific substrates in different subcellular regions of the cell.
By subcellularly specifically expressing different BSL protein members, Dong Juan’s team found that BSL members localized on the cell membrane promote the activity of the upstream kinase YODA (MAPKKK) in the MAPK signaling cascade pathway by dephosphorylation, thereby activating the MAPK signaling cascade pathway, resulting in the phosphorylation of SPCH, a key transcription factor for stomata development in the nucleus, being phosphorylated and degraded, thereby inhibiting the development of stomatals; BSL members located in the nucleus are promoted by interacting with MAPK The direct interaction of the downstream kinase MAPK3/6 in the signaling cascade pathway dephosphorylates MAPK3/6 and inhibits its kinase activity, so that the transcription factor SPCH in the cell nucleus maintains protein stability and thus promotes the development and formation of stomatals.
Figure: The molecular mechanism of the protein phosphatase BSL family that regulates stomata development differently in different cell regions by acting on different substrates
This latest study is a further demonstration of the molecular mechanism of the spatially specific regulation of stomata development in the protein phosphatase BSL family by the protein phosphatase BSL family in spatially specific regulation of plant stomatal development following the study of Professor Dong Juan’s team that spatially specifically aggregates on cell membranes before asymmetric division of stomatal lineage cells (Guo et al., Nature Plants, 2021).
Professor Dong Juan of rutgers University’s Waxman Institute is the corresponding author of the paper, and assistant researcher Guo Xiaoyu is the first author of the paper. (Source: Science Network)
Related paper information:https://www.nature.com/articles/s41467-022-30254-2