Biology subjects

Luginbuehl, L. H.

Publications and source records attributed to Luginbuehl, L. H..

4 recordsLinked to original sources

bioRxiv2025

Conserved spatial patterning of gene expression in independent lineages of C4 plants

O_LIC4 photosynthesis enhances carbon fixation efficiency by reducing photorespiration through the use of an oxygen-insensitive carboxylase and spatial separation of photosynthesis between mesophyll and bundle sheath cells. The C4 pathway has evolved independently in more than sixty plant lineages but molecular mechanisms underpinning this convergence remain unclear. To explore this, we generated high-resolution transcriptome atlases for two independently evolved C4 dicotyledonous species - Gynandropsis gynandra (NAD-ME subtype) and Flaveria bidentis (NADP-ME subtype). C_LIO_LIWe used both single-cell and single-nucleus RNA sequencing to capture gene expression profiles from individual leaf cells, enabling detailed comparison of cell types and transcriptional signatures. C_LIO_LIBoth approaches produced biologically comparable data for major leaf cell types, transcriptomes from single-nucleus sequencing showed lower stress signatures and were more representative of tissue proportions in the leaf. The single-nucleus data revealed that bundle sheath cells from both C4 species share a gene expression pattern associated with mesophyll cells of C3 plants. A conserved set of transcription factors, including members of the C2H2 and DOF families, was identified in the bundle sheath cells of both species. C_LIO_LIThis study presents the first single-cell-resolution transcriptomes for two independent C4 dicot lineages and provides a valuable resource, including a web-based portal for data visualization. C_LI

plant biology↗

bioRxiv2024

Increased chloroplast area in the rice bundle sheath through cell specific perturbation of brassinosteroid signalling

In the leaves of C3 species such as rice, mesophyll cells contain the largest compartment of photosynthetically active chloroplasts. In contrast, plants that use the derived and more efficient C4 photosynthetic pathway have a significant chloroplast compartment in both bundle sheath and mesophyll cells. Accordingly, the evolution of C4 photosynthesis from the ancestral C3 state requires an increase in the chloroplast compartment of the bundle sheath. Here we investigated the potential to increase chloroplast compartment size in rice bundle sheath cells by manipulating brassinosteroid signalling. Treatment with brassinazole, a brassinosteroid biosynthesis inhibitor, increased leaf chlorophyll content and increased the number but decreased the area of chloroplasts in bundle sheath cells. Constitutive overexpression of the BRASSINAZOLE RESISTANT 1 (OsBZR1) transcription factor increased bundle sheath chloroplast area by up to 45% but plants became chlorotic. However, when OsBZR1 was placed under the control of a bundle sheath specific promoter, the negative effects on growth and viability were removed whilst chloroplast area still increased. In summary, we report a role for brassinosteroids in controlling chloroplast area and number in rice and conclude that cell-specific manipulation of brassinosteroid signalling can be used to manipulate the chloroplast compartment in rice bundle sheath cells.

plant biology↗

bioRxiv2023

Single nuclei sequencing reveals C4 photosynthesis is based on rewiring of ancestral cell identity networks

In multicellular systems changes to the patterning of gene expression drive modifications in cell function and trait evolution. One striking example is found in more than sixty plant lineages where compartmentation of photosynthesis between cell types allowed the evolution of the efficient C4 pathway from the ancestral C3 state. The molecular events enabling this transition are unclear. We used single nuclei sequencing to generate atlases for C3 rice and C4 sorghum during photomorphogenesis. Our analysis revealed that initiation of photosynthesis gene expression is conditioned by cell identity. In both species a conserved cistrome defines each cell type, and photosynthesis genes switching expression from mesophyll in rice to bundle sheath in sorghum acquire hallmarks of bundle sheath identity. The sorghum bundle sheath has also acquired gene networks associated with C3 guard cells. We conclude C4 photosynthesis is based on rewiring in cis that exapts cell identity networks of C3 plants.

plant biology↗

bioRxiv2019

Fluorescent reporters for functional analysis in rice leaves

Fluorescent reporters have facilitated non-invasive imaging in multiple plant species and thus allowed analysis of processes ranging from gene expression and protein localization through to cellular patterning. However, in rice, a globally important crop and model species, there are relatively few reports of fluorescent proteins being used in leaves. Fluorescence imaging is particularly difficult in the rice leaf blade, likely due to a high degree of light scattering in this tissue. To address this, we investigated approaches to improve deep imaging in mature rice leaf blades. We found that ClearSee treatment, which has previously been used to visualise fluorescent reporters in whole tissues of plants, led to improved imaging in rice. Removing epidermal and subtending mesophyll cell layers was faster than ClearSee, and also reduced light scattering such that imaging of fluorescent proteins in deeper leaf layers was possible. To expand the range of fluorescent proteins suitable for imaging in rice, we screened twelve whose spectral profiles spanned most of the visible spectrum. This identified five proteins, mTurquoise2, mClover3, mNeonGreen, mKO{kappa} and tdTomato that are robustly expressed and visible in mesophyll cells of stably transformed plants. Using microparticle bombardment, we show that mTurquoise2 and mNeonGreen can be used for simultaneous multicolour imaging of different sub-cellular compartments. Overall, we conclude that mTurquoise2, mClover3, mNeonGreen, mKO{kappa} and tdTomato are suitable for high resolution live imaging of rice leaves, both after transient and stable transformation. Along with the rapid microparticle bombardment method, which allows transient transformation of major cell types in the leaf blade, these fluorescent reporters should greatly facilitate the analysis of gene expression and cell biology in rice.\n\nOne sentence summaryWe report five fluorescent reporters suitable for functional analysis in rice leaves.

plant biology↗