Biology subjects

Guillotin, B.

Publications and source records attributed to Guillotin, B..

4 recordsLinked to original sources

bioRxiv2024

A temporal map of division, chromatin modification, and identity specification in the regenerating Arabidopsis root.

The widespread regenerative capacity of plants is mediated by the ability of specialized cells to reprogram their fate, but the sequential cellular states of regenerating plant cells remain an open question. Here, we characterize the trajectory of cellular reprogramming using single-cell RNA/ATAC-seq, imaging, and mutant analysis. The earliest events were dependent on repressive chromatin modification, where Multiome and genetic analysis showed that Class I histone deacetylases (HDACs) HDA9 and HDA19 were needed to shut down old identities and to prevent a runaway stress response. Cell division mediates a second step needed for the acquisition of many new identity markers, where division rates were tuned by DOF transcription factor OBP1 accelerating and SMR5, 7, and 10 decelerating division rates hours later. The results show how plants actively mediate the loss of remnant identities within hours of injury and then tune cell division rates to rapidly reprogram cells to new identities.

developmental biology↗

bioRxiv2023

A common regulatory switch controls a suite of C4 traits in multiple cell types

The C4 photosynthetic pathway provided a major advantage to plants growing in hot, dry environments, including the ancestors of our most productive crops. Two traits were essential for the evolution of this pathway: increased vein density and the functionalization of bundle sheath cells for photosynthesis. Although GRAS transcriptional regulators, including SHORT ROOT (SHR), have been implicated in mediating leaf patterning in both C3 and C4 species, little is known about what controls the specialized features of the cells that mediate C4 metabolism and physiology. We show in the model monocot, Setaria viridis, that SHR regulates components of multiple cell identities, including chloroplast biogenesis and photosynthetic gene expression in bundle sheath cells, a central feature of C4 plants. Furthermore, we found that it also contributes to the two-cell compartmentalization of the characteristic four-carbon shuttle pathway. Disruption of SHR function clearly reduced photosynthetic capacity and seed yield in mutant plants under heat stress. Together, these results show how cell identities are remodeled by SHR to host the suite of traits characteristic of C4 regulation, which are a main engineering target in non-C4 crops to improve climate resilience.

plant biology↗

bioRxiv2023

Nuclear GSH import precedes coordinated cell cycle changes during regeneration

The plasticity of plant cells underlies their wide capacity to regenerate, with increasing evidence in plants and animals implicating cell cycle dynamics in cellular reprogramming. To investigate the cell cycle during cellular reprogramming, we developed a comprehensive set of cell cycle phase markers in the Arabidopsis root. Using single-cell RNA-seq profiles and live imaging during regeneration, we found that a subset of cells near an ablation injury dramatically increases division rate by truncating G1. Cells in G1 undergo a transient nuclear peak of glutathione (GSH) prior to coordinated entry into S phase followed by rapid divisions and cellular reprogramming. A symplastic block of the ground tissue impairs regeneration, which is rescued by exogenous GSH. We propose a model in which GSH from the outer tissues is released upon injury licensing an exit from G1 near the wound to induce rapid cell division and reprogramming.

plant biology↗

bioRxiv2023

A rapid and sensitive multiplex, whole mount RNA fluorescence in situ hybridization and immunohistochemistry protocol

In the past few years, there has been an explosion in single-cell transcriptomics datasets, yet in vivo confirmation of these datasets is hampered in plants due to lack of robust validation methods. Likewise, modeling of plant development is hampered by paucity of spatial gene expression data. RNA fluorescence in situ hybridization (FISH) enables investigation of gene expression in the context of tissue type. Despite development of FISH methods for plants, easy and reliable whole mount FISH protocols have not yet been reported. We adapt a 3-day whole mount RNA-FISH method for plant species based on a combination of prior protocols that employs hybridization chain reaction (HCR), which amplifies the probe signal in an antibody-free manner. Our whole mount HCR RNA-FISH method shows expected spatial signals with low background for gene transcripts with known spatial expression patterns in Arabidopsis inflorescences and monocot roots. It allows simultaneous detection of three transcripts in 3D. We also show that HCR RNA-FISH can be combined with endogenous fluorescent protein detection and with our improved immunohistochemistry (IHC) protocol. The whole mount HCR RNA-FISH and IHC methods allow easy investigation of 3D spatial gene expression patterns in entire plant tissues.

molecular biology↗