ORCID Profile
0000-0003-0964-9327
Current Organisations
The University of Newcastle
,
University of Sydney
,
Macquarie University Faculty of Science
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Publisher: Springer Science and Business Media LLC
Date: 09-11-2015
DOI: 10.1038/NG.3439
Abstract: As there are numerous pathogen species that cause disease and limit yields of crops, such as wheat (Triticum aestivum), single genes that provide resistance to multiple pathogens are valuable in crop improvement. The mechanistic basis of multi-pathogen resistance is largely unknown. Here we use comparative genomics, mutagenesis and transformation to isolate the wheat Lr67 gene, which confers partial resistance to all three wheat rust pathogen species and powdery mildew. The Lr67 resistance gene encodes a predicted hexose transporter (LR67res) that differs from the susceptible form of the same protein (LR67sus) by two amino acids that are conserved in orthologous hexose transporters. Sugar uptake assays show that LR67sus, and related proteins encoded by homeoalleles, function as high-affinity glucose transporters. LR67res exerts a dominant-negative effect through heterodimerization with these functional transporters to reduce glucose uptake. Alterations in hexose transport in infected leaves may explain its ability to reduce the growth of multiple biotrophic pathogen species.
Publisher: Oxford University Press (OUP)
Date: 14-01-2019
DOI: 10.1093/JXB/ERZ003
Publisher: Oxford University Press (OUP)
Date: 06-10-2019
DOI: 10.1093/JXB/ERZ443
Abstract: Transfer cells are characterized by an lified plasma membrane area supported on a wall labyrinth composed of a uniform wall layer (UWL) from which wall ingrowth (WI) papillae arise. Adaxial epidermal cells of developing Vicia faba cotyledons, when placed in culture, undergo a rapid (hours) trans-differentiation to a functional epidermal transfer cell (ETC) phenotype. The trans-differentiation event is controlled by a signalling cascade comprising auxin, ethylene, apoplasmic reactive oxygen species (apoROS), and cytosolic Ca2+. Apoplasmic hydrogen peroxide (apoH2O2) was confirmed as the apoROS regulating UWL and WI papillae formation. Informed by an ETC-specific transcriptome, a pharmacological approach identified a temporally changing cohort of H2O2 biosynthetic enzymes. The cohort contained a respiratory burst oxidase homologue, polyamine oxidase, copper amine oxidase, and a suite of class III peroxidases. Collectively these generated two consecutive bursts in apoH2O2 production. Spatial organization of biosynthetic/catabolic enzymes was deduced from responses to pharmacologically blocking their activities on the cellular and subcellular distribution of apoH2O2. The findings were consistent with catalase activity constraining the apoH2O2 signal to the outer periclinal wall of the ETCs. Strategic positioning of class III peroxidases in this outer domain shaped subcellular apoH2O2 signatures that differed during assembly of the UWL and WI papillae.
Publisher: Wiley
Date: 07-08-2020
DOI: 10.1111/NPH.16707
Abstract: Transfer cells (TCs) support high nutrient rates into, or at symplasmic discontinuities within, the plant body. Their transport capacity is conferred by an lified plasma membrane surface area, enriched in nutrient transporters, supported on an intricately invaginated wall labyrinth (WL). Thus, development of the WL is at the heart of TC function. Enquiry has shifted from describing WL architecture and formation to discovering mechanisms regulating WL assembly. Experimental systems used to examine these phenomena are critiqued. Considerable progress has been made in identifying master regulators that commit stem cells to a TC fate (e.g. the maize Myeloblastosis (MYB)‐related R1‐type transcription factor) and signals that induce differentiated cells to undergo trans ‐differentiation to a TC phenotype (e.g. sugar, auxin and ethylene). In addition, signals that provide positional information for assembly of the WL include apoplasmic hydrogen peroxide and cytosolic Ca 2+ plumes. The former switches on, and specifies the intracellular site for WL construction, while the latter creates subdomains to direct assembly of WL invaginations. Less is known about macromolecule species and their spatial organization essential for WL assembly. Emerging evidence points to a dependency on methyl‐esterified homogalacturonan accumulation, unique patterns of cellulose and callose deposition and spatial positioning of arabinogalactan proteins.
Publisher: F1000 Research Ltd
Date: 06-12-2017
DOI: 10.12688/F1000RESEARCH.12577.1
Abstract: The phloem plays a central role in transporting resources and signalling molecules from fully expanded leaves to provide precursors for, and to direct development of, heterotrophic organs located throughout the plant body. We review recent advances in understanding mechanisms regulating loading and unloading of resources into, and from, the phloem network highlight unresolved questions regarding the physiological significance of the vast array of proteins and RNAs found in phloem saps and evaluate proposed structure/function relationships considered to account for bulk flow of sap, sustained at high rates and over long distances, through the transport phloem.
Publisher: Wiley
Date: 12-06-2023
DOI: 10.1111/NPH.19058
Abstract: Sugar loading of developing seeds comprises a cohort of transport events that contribute to reproductive success and seed yield. Understanding these events is most advanced for grain crops (Brassicaceae, Fabaceae and Gramineae) and Arabidopsis. For these species, 75–80% of their final seed biomass is derived from phloem‐imported sucrose. Sugar loading consecutively traverses three genomically distinct, and symplasmically isolated, seed domains: maternal pericarp/seed coat, filial endosperm and filial embryo. Sink status of each domain co‐ordinately transitions from growth to storage. The latter is dominated by embryos (Brassicaceae and Fabaceae) or endosperms (Gramineae). Intradomain sugar transport occurs symplasmically through plasmodesmata. Interdomain sugar transport relies on plasma‐membrane transporters operating in efflux (maternal and endosperm) or influx (endosperm and embryo) modes. Discussed is substantial progress made in identifying, and functionally evaluating, sugar symporters (STPs, SUTs or SUCs) and uniporters (SWEETs). These findings have underpinned a mechanistic understanding of seed loading. Less well researched are possible physical limitations imposed by hydraulic conductivities of differentiating protophloem and of subsequent plasmodesmal transport. The latter is coupled with sugar homeostasis within each domain mediated by sugar transporters. A similar conclusion is ascribed to fragmentary understanding of regulatory mechanisms integrating transport events with seed growth and storage.
Publisher: Oxford University Press (OUP)
Date: 16-12-2016
DOI: 10.1104/PP.16.01594
Publisher: Wiley
Date: 08-2021
DOI: 10.1002/EXP.20210002
Abstract: Biological applications of nanomaterials as delivery carriers have been embedded in traditional biomedical research for decades. Despite lagging behind, recent significant breakthroughs in the use of nanocarriers as tools for plant biotechnology have created great interest. In this Perspective, we review the outstanding recent works in nanocarrier‐mediated plant transformation and its agricultural applications. We analyze the chemical and physical properties of nanocarriers determining their uptake efficiency and transport throughout the plant body.
No related grants have been discovered for John Patrick.