Biology subjects

Ho, C.-M. K.

Publications and source records attributed to Ho, C.-M. K..

4 recordsLinked to original sources

bioRxiv2024

Guard-cell phytosterol homeostasis is critical for proper stomatal development

Stomata regulate gas exchange and control water loss in response to the environmental stimuli and their distribution in the leaf epidermis is tightly regulated during development to ensure proper patterns. Although many studies have focused on the function of early stomatal lineage cells, little is known about the role of mature guard cells (GCs) in maintaining stomatal distribution. Here, we identified a previously uncharacterized enzyme, GDSL-type sterol esterase (GSEase), that is specifically expressed in mature guard cells and catalyzes lipid droplet-stored phytosterol ester degradation. Loss of GSEase decreased the level of free campesterol, a biosynthetic precursor of brassinosteroids (BRs), reduced BR level, and increased stomatal density in leaves, which could be further rescued by increasing the BR signaling. Furthermore, selectively reducing the BR response in GCs by utilizing the GSEase promoter-driven det2-1, a mutation causing BR biosynthesis deficiency, resulted in an elevated stomatal count, as demonstrated in gsease plants. These results indicate that GSEase plays a critical role in maintaining phytosterol homeostasis in GCs and the released phytosterols suppress the initiation of stomatal development in adjacent cells though the BR pathway.

plant biology↗

bioRxiv2024

StomaVision: stomatal trait analysis through deep learning

StomaVision is an automated tool designed for high-throughput detection and measurement of stomatal traits, such as stomatal number, pore size, and closure rate. It provides insights into plant responses to environmental cues, streamlining the analysis of micrographs from field-grown plants across various species, including monocots and dicots. Enhanced by a novel collection method that utilizes video recording, StomaVision increases the number of captured images for robust statistical analysis. Accessible via an intuitive web interface at and available for local use in a containerized environment at , this tool ensures long-term usability by minimizing the impact of software updates and maintaining functionality with minimal setup requirements. The application of StomaVision has provided significant physiological insights, such as variations in stomatal density, opening rates, and total pore area under heat stress. These traits correlate with critical physiological processes, including gas exchange, carbon assimilation, and water use efficiency, demonstrating the tools utility in advancing our understanding of plant physiology. The ability of StomaVision to identify differences in responses to varying durations of heat treatment highlights its value in plant science research. Plain language summaryStomaVision is a tool that automatically counts and measures tiny openings on plant leaves, helping us learn how plants deal with their surroundings. It is easy to use and works well with various plant species. This tool helps scientists see how plants change under stress, making plant research easier and more accurate.

plant biology↗

bioRxiv2023

The HOMEODOMAIN-Like protein HDL mediates chromatin organization and rewires leaf epidermal patterning

The Arabidopsis leaf epidermis is comprised of trichomes, pavement cells, and stomata, originating from versatile precursor cells capable of dividing or differentiating to create unique epidermal patterns. The mechanism governing these transitions and the maintenance of cell heterogeneity remains unclear. In this study, we identified a novel homeodomain-like superfamily protein, HDL, localized in chromocenters and playing a role in chromatin organization. HDL interacts with histone deacetylase 6 (HDA6) and methyltransferases, indicating its function in modulating chromatin accessibility. In hdl mutants, we observed moderately increased chromatin accessibility in the promoter region of protein-coding genes, along with reduced stomatal density and elevated trichome numbers on leaf surfaces. Corresponding to these phenotypes, stomatal-related gene expression decreased, while a transcriptional reporter for GLABRA2, a trichome initiation gene, exhibited higher and more variable expression levels. These findings highlight how HDL-mediated chromatin organization influences epidermal cell fate by modulating gene expression and enhancing cell heterogeneity within the leaf epidermis. One Sentence SummaryA homeodomain-like protein functions with histone modifiers to regulate chromatin and influence cell fate decisions.

plant biology↗

bioRxiv2021

Misregulation of MYB16 causes stomatal cluster formation by disrupting polarity in asymmetric cell division

Stomata and leaf cuticle regulate water evaporation from the plant body and balance the trade-off between photosynthesis and water loss. We identified MYB16, a key transcription factor controlling cutin biosynthesis, from previous stomatal lineage ground cell (SLGC)-enriched transcriptome study. The preferential localization of MYB16 in SLGCs but not meristemoids suggests a link between cutin synthesis and stomatal development. Here, we showed that downregulation of MYB16 in meristemoids was directly mediated by the stomatal master transcription factor, SPEECHLESS (SPCH). The suppression of MYB16 before asymmetric division was crucial for stomatal patterning because overexpression or ectopic expression of MYB16 in meristemoids increased impermeability and elevated stomatal density and clusters. The aberrant pattern of stomata was due to reduced and disrupted establishment of polarity during asymmetric cell division. Manipulating polarity by growing seedlings on hard agar rescued stomatal clusters and polarity defects in MYB16 ectopic lines. By expressing a cutinase in MYB16 ectopic lines, stomatal clustering was reduced, which suggests that the ectopic accumulation of cuticle affects the polarity in asymmetrically dividing cells and causes clustered stomata. Taken together, inhibiting MYB16 expression by SPCH in early stomatal lineage is required to correctly place the polarity complex for proper stomatal patterning during leaf morphogenesis.

plant biology↗