Julian M Hibberd

• PhD
• University of Cambridge

Gynandropsis gynandra is a nutrient-rich, climate-resilient, C 4 under-utilised crop with potential to enhance food security in low-input farming systems. To support its genetic improvement, we performed linkage mapping using two F 2 populations (213 and 187 individuals) derived from Malaysian and Malawian founder lines. Under controlled greenhouse...

Research in Arabidopsis thaliana has a powerful influence on our understanding of gene functions and pathways. However, not everything translates from Arabidopsis to crops and other plants. Here, a group of experts consider instances where translation has been lost and why such translation is not possible or is challenging. First, despite great eff...

C 4 photosynthesis has arisen from the ancestral C 3 state in over sixty lineages of angiosperms. It is widely accepted that an early step in C 4 evolution is associated with the appearance of so-called C 2 photosynthesis caused by loss of glycine decarboxylase activity from mesophyll cells followed by activation in the bundle sheath. Although chan...

The liverwort Marchantia polymorpha is a widely used model organism for studying land plant biology, which has also proven to be a promising testbed for bioengineering. CRISPR/Cas9 technology has emerged as a transformative tool for precise genome modifications in M. polymorpha . However, a robust method for the simultaneous expression of multiple...

In the leaves of C3 species such as rice (Oryza sativa), 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 considerable chloroplast compartment in both bundle sheath and mesophyll cells. Accordingly, the evolution of...

C4 photosynthesis is used by the most productive plants on the planet, and compared with the ancestral C3 pathway, it confers a 50% increase in efficiency¹. In more than 60 C4 lineages, CO2 fixation is compartmentalized between tissues, and bundle-sheath cells become photosynthetically activated². How the bundle sheath acquires this alternate ident...

A sustainable food supply is vital for addressing the challenges of a growing global population and climate change. Gynandropsis gynandra , a nutritious C 4 orphan crop native to Africa and Asia, thrives in low-input agricultural systems, making it a valuable candidate for future food security. This crop also serves as a model for studying C 4 phot...

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 photosynthes...

The C4 pathway has evolved in over sixty lineages of plants and improves photosynthetic efficiency by ~50%. One unifying character of C4 plants is photosynthetic activation of a compartment such as the bundle sheath, but gene regulatory networks controlling this cell type are poorly understood. For example, in Arabidopsis thaliana a bipartite MYC-M...

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 evolution of the efficient C4 pathway from the ancestral C3 state. The molecular events en...

C4 photosynthesis allows increased efficiency and has evolved in more than sixty-six plant lineages. Underpinning this repeated appearance of the C4 pathway is a major transcriptional reprogramming of photosynthesis genes. Here we investigated whether evolution has also significantly modified translational control by comparing the translational dyn...

In leaves of C4 plants, the reactions of photosynthesis become restricted between two compartments. Typically, this allows accumulation of C4 acids in mesophyll (M) cells and subsequent decarboxylation in the bundle sheath (BS). In C4 grasses, proliferation of plasmodesmata between these cell types is thought to increase cell‐to‐cell connectivity t...

Model species continue to underpin groundbreaking plant science research. At the same time, the phylogenetic resolution of the land plant Tree of Life continues to improve. The intersection of these two research paths creates a unique opportunity to further extend the usefulness of model species across larger taxonomic groups. Here we promote the u...

C 4 photosynthesis has arisen from the ancestral C 3 state in over sixty lineages of angio-sperms. It is widely accepted that an early step in C 4 evolution is restriction of glycine decarboxylase activity to bundle sheath cells to generate the so-called C 2 pathway. In C 2 Moricandia species, changes to the cis -regulatory region controlling expre...

Photosynthesis in both crops and natural vegetation allows light energy to be converted into chemical energy, and thus forms the foundation for almost all terrestrial trophic networks on Earth. The efficiency of photosynthetic energy conversion plays a crucial role in determining the portion of incident solar radiation that can be used to generate...

Chloroplast biogenesis is dependent on master regulators from the Golden2-like (GLK) family of transcription factors, but higher order glk mutants contain residual chlorophyll and therefore other proteins must also be involved. Here we identify MYB-related transcription factors as regulators of chloroplast biogenesis in the liverwort Marchantia pol...

Compared with the ancestral C3 state, C4 photosynthesis occurs at higher rates with improved water and nitrogen use efficiencies. In both C3 and C4 plants, rates of photosynthesis increase with light intensity and are maximal around midday. We determined that in the absence of light or temperature fluctuations, photosynthesis in maize (Zea mays) pe...

Background: It has been proposed that engineering the C4 photosynthetic pathway into C3 crops could significantly increase yield. This goal requires an increase in the chloroplast compartment of bundle sheath cells in C3 species. To facilitate large-scale testing of candidate regulators of chloroplast development in the rice bundle sheath, a simpl...

C4 photosynthesis has evolved multiple times in the angiosperms and typically involves alterations to the biochemistry, cell biology and development of leaves. One common modification found in C4 plants compared with the ancestral C3 state is an increase in vein density such that the leaf contains a larger proportion of bundle sheath cells. Recent...

Compared with the ancestral C3 state, C4 photosynthesis enables higher rates of photosynthesis as well as improved water and nitrogen use efficiencies. In both C3 and C4 plants rates of photosynthesis increase with light intensity and so are maximal around midday. We report that in the absence of light or temperature fluctuations, photosynthesis in...

Land plants comprise two large monophyletic lineages, the vascular plants and the bryophytes, which diverged from their most recent common ancestor approximately 480 million years ago. Of the three lineages of bryophytes, only the mosses and the liverworts are systematically investigated, while the hornworts are understudied. Despite their importan...

Background It has been proposed that engineering the C 4 photosynthetic pathway into C 3 crops could significantly increase yield. This goal requires an increase in the chloroplast compartment of bundle sheath cells in C 3 species. To facilitate large-scale testing of candidate regulators of chloroplast development in the rice bundle sheath, a simp...

C4 photosynthesis has evolved by repurposing enzymes found in C3 plants. Compared with the ancestral C3 state, accumulation of C4 cycle proteins is enhanced. We used de-etiolation of C4 Gynandropsis gynandra and C3 Arabidopsis thaliana to understand this process. C4 gene expression and chloroplast biogenesis in G. gynandra were tightly coordinated....

Chilling stress has the potential to significantly decrease growth and yield of sensitive crop plants such as maize. Based on previous work, high light during chilling may exacerbate stress via enhanced photoinhibition but may also aid acclimation responses to chilling. To further understand molecular processes behind responses to chilling with and...

C 4 photosynthesis has evolved multiple times in the angiosperms and typically involves alterations to the biochemistry, cell biology and development of leaves. One common modification found in C 4 plants compared with the ancestral C 3 state is an increase in vein density such that the leaf contains a larger proportion of bundle sheath cells. Rece...

Gynandropsis gynandra (Cleomaceae) is a cosmopolitan leafy vegetable and medicinal plant, which has also been used as a model to study C4 photosynthesis due to its evolutionary proximity to C3 Arabidopsis (Arabidopsis thaliana). Here, we present the genome sequence of G. gynandra, anchored onto 17 main pseudo-molecules with a total length of 740 Mb...

Gynandropsis gynandra (Cleomaceae) is a cosmopolitan leafy vegetable and medicinal plant, which has also been used as a model to study C4 photosynthesis due to its evolutionary proximity to C3 Arabidopsis (Arabidopsis thaliana). Here, we present the genome sequence of G. gynandra, anchored onto 17 main pseudo-molecules with a total length of 740 Mb...

Photosynthesis in eukaryotic cells takes place in specialised plastids. The regulation of plastid development is crucial for multicellular systems such as plants. Two families of transcription factors known as Golden2-like (GLK) and GATA regulate plant chloroplast development, and the miR171-targeted SCARECROW-LIKE (SCL) GRAS transcription factors...

In leaves of C 4 plants the reactions of photosynthesis become restricted between two compartments. Typically, this allows accumulation of C 4 acids in mesophyll cells and subsequent decarboxylation in the bundle sheath. In C 4 grasses proliferation of plasmodesmata between these cell types is thought to increase cell-to-cell connectivity to allow...

Reactive oxygen species (ROS) and the photoreceptor protein phytochrome B (phyB) play a key role in plant acclimation to stress. However, how phyB that primarily functions in the nuclei impacts ROS signaling mediated by respiratory burst oxidase homolog (RBOH) proteins that reside on the plasma membrane, during stress, is unknown. Arabidopsis thali...

A key feature of C4 Kranz anatomy is the presence of an enlarged, photosynthetically highly active bundle sheath whose cells contain large numbers of chloroplasts. With the aim to identify novel candidate regulators of C4 bundle sheath development, we performed an activation tagging screen with Arabidopsis thaliana. The reporter gene used encoded a...

Leaves of shade-avoiding plants such as Arabidopsis (Arabidopsis thaliana) change their growth pattern and position in response to low red to far-red ratios (LRFRs) encountered in dense plant communities. Under LRFR, transcription factors of the phytochrome interacting factor (PIF) family are de-repressed. PIFs induce auxin production, which is req...

Gynandropsis gynandra (Cleomaceae) is a cosmopolitan leafy vegetable and medicinal plant, which has also been used as a model to study C 4 photosynthesis due to its evolutionary proximity to Arabidopsis. Here, we present a high-quality genome sequence of G. gynandra , anchored onto 17 main super-scaffolds with a total length of 740 Mb, an N50 of 42...

In biological discovery and engineering research there is a need to spatially and/or temporally regulate transgene expression. However, the limited availability of promoter sequences that are uniquely active in specific tissue‐types and/or at specific times often precludes co‐expression of multiple transgenes in precisely‐controlled developmental c...

Leaves of shade avoiding plants like Arabidopsis thaliana change their growth pattern and position in response to a low red to far-red ratio (LRFR) that is encountered in dense plant communities. In LRFR, transcription factors of the phytochrome interacting family (PIFs) are de-repressed. PIFs induce auxin production, which is required to promote l...

Grafting is possible in both animals and plants. Although in animals the process requires surgery and is often associated with rejection of non-self, in plants grafting is widespread, and has been used since antiquity for crop improvement¹. However, in the monocotyledons, which represent the second largest group of terrestrial plants and include ma...

In C4 plants, the enzymatic machinery underpinning photosynthesis can vary, with, for example, three distinct C4 acid decarboxylases being used to release CO2 in the vicinity of RuBisCO. For decades, these decarboxylases have been used to classify C4 species into three biochemical sub‐types. However, more recently, the notion that C4 species mix an...

Plants are essential for life on Earth converting light into chemical energy in the form of sugars. To adjust for changes in light intensity and quality, and to become as efficient as possible in harnessing light, plants utilize multiple light receptors, signaling, and acclimation mechanisms. In addition to altering plant metabolism, development an...

Chloroplasts are best known for their role in photosynthesis, but they also allow nitrogen and sulphur assimilation, amino acid, fatty acid, nucleotide and hormone synthesis. How chloroplasts develop is therefore relevant to these diverse and fundamental biological processes, but also to attempts at their rational redesign. Light is strictly requir...

Reducing photorespiration in C3 crops could significantly increase rates of photosynthesis and yield. One method to achieve this would be to integrate C4 photosynthesis into C3 species. This objective is challenging as it involves engineering incompletely understood traits into C3 leaves including complex changes to their biochemistry, cell biology...

The engineering of C4 photosynthetic activity into the C3 plant rice has the potential to nearly double rice yields. To engineer a two‐cell photosynthetic system in rice, the rice bundle sheath (BS) must be rewired to enhance photosynthetic capacity. Here, we show that BS chloroplast biogenesis is enhanced when the transcriptional activator, Oryza...

C4 photosynthesis is a remarkable complex trait, elucidations of the evolutionary trajectory of C4 photosynthesis from its ancestral C3 pathway can help us better understand the generic principles of the evolution of complex traits and guide the engineering of C3 crops for higher yields. Here, we used the genus Flaveria that contains C3, C3–C4, C4-...

Best poster award

Significance The ability of plants to initiate systemic responses to local biotic and abiotic stress is well known. One such example takes place after exposure to high-light episodes and involves an initial, local accumulation of reactive oxygen species (ROS) in the region exposed to excessive light. Overexcitation of the photosynthetic apparatus h...

Leaves comprise multiple cell types but our knowledge of the patterns of gene expression that underpin their functional specialization is fragmentary. Our understanding and ability to undertake the rational redesign of these cells is therefore limited. We aimed to identify genes associated with the incompletely understood bundle sheath of C3 plants...

Leaves comprise multiple cell types but our knowledge of the patterns of gene expression that underpin their functional specialization is fragmentary. Our understanding and ability to undertake rational redesign of these cells is therefore limited. We aimed to identify genes associated with the incompletely understood bundle sheath of C 3 plants, w...

We generated antisense constructs targeting two of the five Rubisco small subunit genes (OsRBCS2 and 4) which account for between 30-40% of the RBCS transcript abundance in leaf blades. The constructs were driven by a maize phosphoenolpyruvate carboxylase (PEPC) promoter known to have enriched expression in mesophyll cells (MCs). In the resulting l...

C4 photosynthesis is a remarkable complex trait, elucidations of the evolutionary trajectory of C4 photosynthesis from its ancestral C3 pathway can help us better understand the generic principles of the evolution of complex trait and guide the engineering of C3 crops for higher yields. Here, we used the genus Flaveria that contains C3, C3-C4, C4-l...

C4 photosynthesis evolved repeatedly from the ancestral C3 state, improving photosynthetic efficiency by ~50%. In most C4 lineages, photosynthesis is compartmented between mesophyll and bundle sheath cells, but how gene expression is restricted to these cell types is poorly understood. Using the C3 model Arabidopsis thaliana, we identified cis-elem...

We generated antisense constructs targeting two of the five Rubisco small subunit genes (OsRBCS2 and 4) which account for between 30-40% of the RBCS transcript abundance in leaf blades. The constructs were driven by a maize phosphoenolpyruvate carboxylase (PEPC) promoter known to have enriched expression in mesophyll cells (MCs). In the resulting l...

When exposed to high light plants produce reactive oxygen species (ROS). In Arabidopsis thaliana local accumulation of ROS preferentially takes place in bundle sheath strands, but little is known about how this response takes place. Using rice and the ROS probes diaminobenzidine and 2',7'-dichlorodihydrofluorescein diacetate, we found that after ex...

The efficient C4 pathway is based on strong up-regulation of genes found in C3 plants, but also compartmentation of their expression into distinct cell-types such as the mesophyll and bundle sheath. Transcription factors associated with these phenomena have not been identified. To address this, we undertook genome-wide analysis of transcript accumu...

Introduction of a C 4 photosynthetic pathway into C 3 rice ( Oryza sativa ) requires installation of a biochemical pump that concentrates CO 2 at the site of carboxylation in modified bundle sheath cells. To investigate the feasibility of this, we generated a quadruple line that simultaneously expresses four of the core C 4 photosynthetic enzymes f...

Convergent trait evolution is a recurrent phenomenon in all domains of the tree of life. While some convergent traits are caused by simple sequence changes, many are associated with extensive changes to the sequence and regulation of large cohorts of genes. It is unknown how organisms traverse this expansive genotype space to assemble such complex...

Fluorescent reporters have facilitated non‐invasive imaging in multiple plant species and thus allowed the analysis of processes ranging from gene expression and protein localization 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. F...

The engineering process of C4 photosynthesis into C3 plants requires an increased activity of phosphoenolpyruvate carboxylase (PEPC) in the cytosol of leaf mesophyll cells. The literature varies on the physiological effect of transgenic maize (Zea mays) PEPC (ZmPEPC) leaf expression in Oryza sativa (rice). Therefore, to address this issue, leaf–atm...

Green plants (Viridiplantae) include around 450,000–500,000 species1,2 of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida),...

The majority of plants use C3 photosynthesis, but over 60 independent lineages of angiosperms have evolved the C4 pathway. In most C4 species, photosynthesis gene expression is compartmented between mesophyll and bundle-sheath cells. We performed DNaseI sequencing to identify genome-wide profiles of transcription factor binding in leaves of the C4...

Green plants (Viridiplantae) include around 450,000–500,000 species1,2 of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida),...

Achieving global food security for the estimated 9 billion people by 2050 is a major scientific challenge. Crop productivity is fundamentally restricted by the rate of fixation of atmospheric carbon. The dedicated enzyme, RubisCO, has a low turnover and poor specificity for CO2. This limitation of C3 photosynthesis (the basic carbon-assimilation pa...

Laser Capture Microdissection is a powerful tool that allows thin slices of specific cell types to be separated from one another. However, the most commonly used protocol, which involves embedding tissue in paraffin wax, results in severely degraded RNA. Yields from low abundance cell types of leaves are particularly compromised. We reasoned that t...

Methods for RNA isolation These methods were originally included in Appendix S1 of "Evaluating Methods for Isolating Total RNA and Predicting the Success of Sequencing Phylogenetically Diverse Plant Transcriptomes" Marc T. J. Johnson et al. PLOS ONE, November 21, 2012. https://doi.org/10.1371/journal.pone.0050226 Many of the protocols share element...

This protocol is part of a collection of eighteen protocols used to isolate total RNA from plant tissue. (RNA Isolation from Plant Tissue Collection: https://www.protocols.io/view/rna-isolation-from-plant-tissue-439gyr6) and was originally published as part of Appendix S1 of "Evaluating Methods for Isolating Total RNA and Predicting the Success of...

The majority of plants use C 3 photosynthesis, but over sixty independent lineages of angiosperms have evolved the C 4 pathway. In most C 4 species, photosynthesis gene expression is compartmented between mesophyll and bundle sheath cells. We performed DNaseI-SEQ to identify genome-wide profiles of transcription factor binding in leaves of the C 4...

The influence of reduced glycine decarboxylase complex (GDC) activity on leaf-atmosphere CO2 and 13CO2 exchange was tested in transgenic Oryza sativa with the knocked down (KD) of the GDC H-subunit in the leaf M cells. Leaf measurements on transgenic (gdch-KD) and wild-type (WT) plants were carried out in the light under photorespiratory and low-ph...

Background C 4 photosynthesis is a remarkable complex trait, elucidations of the evolutionary trajectory of C 4 photosynthesis from its ancestral C 3 pathway can help us to better understand the generic principles of complex trait evolution and guide engineering of C 3 crops for higher yields. We used the genus Flaveria that contains C 3 , C 3 -C 4...

In multicellular organisms the specification of distinct tissues within organs allows compartmentation of complex processes. However, the mechanisms that allow gene expression to be restricted to such tissues are poorly understood. To better understand this process, we focused on bundle sheath expression of the gene encoding the MYB76 transcription...

The bundle sheath provides a conduit linking veins and mesophyll cells. In C3 Arabidopsis thaliana it also plays important roles in oxidative stress and sulphur metabolism. However, the mechanisms responsible for the patterns of gene expression that underpin these metabolic specialisations are poorly understood. Here we used the A. thaliana SULTR2;...

Droplet-based microfluidics has been used to facilitate high-throughput analysis of individual prokaryote and mammalian cells. However, there is a scarcity of similar workflows applicable to rapid phenotyping of plant systems where phenotyping analyses typically are time-consuming and low-throughput. We report on-chip encapsulation and analysis of...

Sorting of M. polymorpha protoplasts. Bright field and fluorescence micrographs of microdroplets sorted into positive and negative channels based on their mVenus fluorescence intensity. Scale bars; 50 μm. (PDF)

Encapsulation of A. thaliana protoplasts. A) Bright field and (B) chlorophyll fluorescence micrographs of individual A. thaliana leaf protoplasts encapsulated in microdroplets. (C) Representative photomultiplier tube (PMT) readout of chlorophyll fluorescence intensity represented as arbitrary fluorescent units (AFU) recorded over 17.5 s. Each line...

Engineering C4 photosynthesis into C3 crops could substantially increase their yield by alleviating photorespiratory losses. This objective is challenging because the C4 pathway involves complex modifications to the biochemistry, cell biology and anatomy of leaves. Forward genetics has provided limited insight into the mechanistic basis of these pr...

C4 photosynthesis has evolved repeatedly from the ancestral C3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the world's most productive crops. The C4 cycle is accomplished through cell...

It has been proposed that introducing C 4 photosynthesis into C 3 crops would increase yield. The simplest scheme in- volves concentrating carbon originating from the cytosol in the chloroplast stroma of mesophyll cells without altering leaf or cell anatomy. Photosynthetic efficiency would then strongly depend on the chloroplast envelope permeabili...

If the highly efficient C4 photosynthesis pathway could be transferred to crops with the C3 pathway there could be yield gains of up to 50%. It has been proposed that the multiple metabolic and developmental modifications associated with C4 photosynthesis are underpinned by relatively few master regulators that have allowed the evolution of C4 phot...

Engineering C4 photosynthesis into C3 crops such as rice or wheat could substantially increase their yield by alleviating photorespiratory losses1,2. This objective is challenging because the C4 pathway involves complex modifications to the biochemistry, cell biology and anatomy of leaves3. Forward genetics has provided limited insight into the mec...

C 4 photosynthesis has evolved repeatedly from the ancestral C 3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the world’s most productive crops. The C 4 cycle is accomplished through c...

The bundle sheath provides a conduit linking veins and mesophyll cells. In C 3 Arabidopsis thaliana it also plays important roles in oxidative stress and sulphur metabolism. However, the mechanisms responsible for the patterns of gene expression that underpin these metabolic specialisations are poorly understood. Here we used the A. thaliana SULTR2...