Biology subjects

Smoot, N. K.

Publications and source records attributed to Smoot, N. K..

5 recordsLinked to original sources

bioRxiv2026

DNA demethylation suppresses a state of enhanced cellular pluripotency and regeneration competence in Arabidopsis.

The plant kingdom exhibits a wide range of phenotypic variation in capacity to regenerate tissues and organs, from whole-plant vegetative propagation via cuttings, to recalcitrance even under optimized tissue culture. Currently, the molecular pathways underpinning this phenotypic variation are poorly understood. Here, we report that Arabidopsis mutants of the DNA demethylase pathway exhibit dramatically enhanced regeneration and the ability to propagate whole plants from cuttings without the use of exogenous hormones. Vegetatively propagated plants possess a shared regeneration signature of de novo DNA methylation gains at the transcription start sites of many genes, including approximately 30 genes involved in cellular pluripotency and tissue regeneration. These methylation changes can be inherited through sexual reproduction and are associated with exacerbated transcriptomic changes. We propose that loss of the DNA demethylase pathway unlocks a path on the epigenetic landscape towards increased pluripotency and regeneration without the application of exogenous hormones.

plant biology↗

bioRxiv2026

Genetic encoding of climate-responsive stomatal developmental plasticity in tomato

Flexible developmental programs enable plants to customize their organ size and cellular composition. In leaves of eudicots, the stomatal lineage produces two essential cell types, stomata and pavement cells, and plants can adjust the total numbers and ratios of these cell types in response to external cues. Central to this flexibility is the stomatal lineage-initiating transcription factor, SPEECHLESS (SPCH). Here we explore the mechanisms underlying SPCHs involvement in environmental response. Using multiplexed CRISPR/Cas9 editing of SlSPCH cis-regulatory sequences in tomato, we identified variants with altered stomatal development responses to drought, light and temperature cues. By creating and live-cell tracking translational reporters of SlSPCH and its paralogues SlMUTE and SlFAMA, we revealed the corresponding cellular events that lead to the environmental change-driven responses in stomatal production and leaf form. Plants bearing the novel reporters and SlSPCH variants are powerful resources for fundamental and applied studies of tomato resilience in response to climate change.

plant biology↗

bioRxiv2023

Targeting editing of tomato SPEECHLESS cis-regulatory regions generates plants with altered stomatal density in response to changing climate conditions

Flexible developmental programs enable plants to customize their organ size and cellular composition. In leaves of eudicots, the stomatal lineage produces two essential cell types, stomata and pavement cells, but the total numbers and ratio of these cell types can vary. Central to this flexibility is the stomatal lineage initiating transcription factor, SPEECHLESS (SPCH). Here we show, by multiplex CRISPR/Cas9 editing of SlSPCH cis-regulatory sequences in tomato, that we can identify variants with altered stomatal development responses to light and temperature cues. Analysis of tomato leaf development across different conditions, aided by newly-created tools for live-cell imaging and translational reporters of SlSPCH and its paralogues SlMUTE and SlFAMA, revealed the series of cellular events that lead to the environmental change-driven responses in leaf form. Plants bearing the novel SlSPCH variants generated in this study are powerful resources for fundamental and applied studies of tomato resilience in response to climate change. Significance statementPlants can change their shape, size and cellular composition in response to environmental cues. Here, by precise gene editing of a core stomatal development regulator gene in tomato, we generate new alleles with enhanced or dampened responses to light and temperature cues. Combined with live imaging of development, we show the genetic and cellular pathways that contribute to customization of the leaf epidermis, and how this could lead to better climate-adapted varieties.

plant biology↗

bioRxiv2021

On the edge: Evolution of polarity protein BASL and the capacity for stomatal lineage asymmetric divisions

Asymmetric and oriented stem cell divisions enable the continued production of patterned tissues. The molecules that guide these divisions include several "polarity proteins" that are localized to discrete plasma membrane domains, are differentially inherited during asymmetric divisions, and whose scaffolding activities can guide division plane orientation and subsequent cell fates. In the stomatal lineages on the surfaces of plant leaves, asymmetric and oriented divisions create distinct cell types in physiologically optimized patterns. The polarity protein BASL is a major regulator of stomatal lineage division and cell fate asymmetries in Arabidopsis, but its role in the stomatal lineages of other plants is unclear. Here, using phylogenetic and functional assays, we demonstrate that BASL is a eudicot-specific polarity protein. Among dicots, divergence in BASLs roles may reflect some intrinsic protein differences, but more likely reflects previously unappreciated differences in how asymmetric cell divisions are employed for pattern formation in different species. This multi-species analysis therefore provides insight into the evolution of a unique polarity regulator and into the developmental choices available to cells as they build and pattern tissues. HIGHLIGHTSO_LIBASL is a eudicot-specific regulator of stomatal lineage asymmetric cell divisions C_LIO_LIBASL protein evolution includes stepwise addition of polarity domains to an ancestral MAPK-binding chassis C_LIO_LICellular quiescence and BASL-guided polarity generate proper stomatal spacing in tomato C_LIO_LICell size and fate asymmetries are uncoupled in the tomato stomatal lineage C_LI

plant biology↗

bioRxiv2020

Single-Cell Resolution of Lineage Trajectories in the Arabidopsis Stomatal Lineage and Developing Leaf

Dynamic cell states underlie flexible developmental programs, such as with the stomatal lineage of the Arabidopsis epidermis. Initial stages of the lineage feature asynchronous and indeterminate divisions modulated by environmental cues, enabling cell fate flexibility to generate the requisite density and pattern of stomata for a given environment. It remains unclear, however, how flexibility of cell fates is controlled. Here, we uncovered distinct models of cell state differentiation within Arabidopsis leaf tissue by leveraging single-cell transcriptomics and molecular genetics. Our findings resolved underlying heterogeneity within cell states of the flexible epidermal stomatal lineage, which appear to exist along a continuum, with progressive cell specification. Beyond the early stages of the lineage, we discovered that the core transcriptional regulator SPEECHLESS is required for cell fate commitment to yield stomatal guard cells. Overall, our work has refined the stomatal lineage paradigm and uncovered progressive cell state decisions along lineage trajectories in developing leaves.

plant biology↗