Biology subjects

Vaten, A.

Publications and source records attributed to Vaten, A..

4 recordsLinked to original sources

bioRxiv2025

Fern and gymnosperm SPCH/MUTE and FAMA can regulate multiple cell fate transitions during stomatal development

Stomatal development is driven by a conserved family of basic Helix-loop-helix (bHLH) transcription factors. In the angiosperm model Arabidopsis thaliana, SPEECHLESS (SPCH), MUTE and FAMA show pronounced yet incompletely separated stage-specific functions. How the functional specialization observed within angiosperms evolved has remained unclear. Here, we perform the first functional analysis of stomatal regulators from the fern Ceratopteris richardii and the gymnosperm Picea abies (Norway spruce). We show that both species possess a single SPCH/MUTE-like gene (CrSM and PaSM) together with a single FAMA-like gene (CrFAMA and PaFAMA). Cross-species complementation in Arabidopsis showed that all the four bHLHs displayed broad developmental capacities and promoted asymmetric stomatal-lineage entry divisions, a function associated with angiosperm SPCH. Moreover, PaSM promoted pore-like structure formation in the fama background, indicating a capacity extending into a developmental transition controlled by angiosperm FAMA. To examine the functions of PaSM and PaFAMA in the native context, we generated transgenic spruce lines expressing dominant-negative variants of these genes. Perturbation of either bHLH was associated with fewer epidermal cells between adjacent stomata, whereas the two constructs produced partially distinct effects on mature stomatal-complex morphology. Together, our findings show that the fern and gymnosperm stomatal bHLHs examined here possess broad and overlapping developmental capacities. These results support a model in which the stage-specific functions of angiosperm stomatal regulators evolved through the progressive refinement and partitioning of broader, partially overlapping developmental capacities.

plant biology↗

bioRxiv2024

The dynamic and diverse nature of parenchyma cells in the Arabidopsis root during secondary growth

During the process of secondary growth, the vascular cambium produces the conductive xylem and phloem cells, while the phellogen (cork cambium) deposit phellem (cork) as the outermost protective barrier. Although most of the secondary tissues is made up by parenchyma cells which are also produced by both cambia, their diversity and function are poorly understood. Here we combined single-cell RNA sequencing analysis with lineage tracing to recreate developmental trajectories of the cell types in the Arabidopsis root undergoing secondary growth. By analysing 93 reporter lines, we were able to identify 20 different cell types or cell states, many of which have not been described before. We additionally observed distinct transcriptome signatures of parenchyma cells depending on their maturation state and proximity to the conductive cell types. Our data shows that both xylem and phloem parenchyma tissues are required for normal formation of conductive tissue cell types. Furthermore, we showed that mature phloem parenchyma gradually obtains periderm identity, and this transition can be accelerated by jasmonate or wounding. Thus, our study reveals the remarkable dynamic and diverse nature of parenchyma cells during secondary growth.

plant biology↗

bioRxiv2022

Slow and not so furious: de novo stomatal pattern formation during plant embryogenesis

The fates of cells on the leaf surface depend on positional cues and environmental signals. New stomata are formed away from existing ones to prevent disadvantageous clustering, but how are the initial precursors positioned? Mature embryos do not have stomata, but we provide transcriptomic, imaging, and genetic evidence that Arabidopsis embryos engage known stomatal fate and patterning factors to create regularly spaced stomatal precursor cells. Analysis of embryos from 35 plant species indicates this trait is conserved across angiosperm clades. Embryonic stomatal patterning in Arabidopsis is established in three stages: first broad SPEECHLESS (SPCH) expression, then coalescence of SPCH and its targets into discrete domains, and finally one round of symmetric division to create stomatal precursors. Lineage progression is then halted until after germination. We show that embryonic stomatal pattern enables quick stomatal differentiation and photosynthetic activity upon germination but also guides the formation of additional stomata as the leaf expands. In addition, key stomatal regulators are prevented from driving the fate transitions they can induce after germination, revealing stage-specific layers of regulation that control lineage progression during embryogenesis.

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↗