Experience

Publications

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Ralstonia solanacearum differentially colonizes roots of resistant and susceptible tomato plants

  Phytopathology

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Ralstonia solanacearum differentially colonizes roots of resistant and susceptible tomato plants

  Phytopathology

• The Subcellular Localization of Ralstonia solanacearum K60 Type III Effectors

  APSNET

  Ralstonia solanacearum is a soil-borne bacterial pathogen that causes Bacterial Wilt disease in over 200 plant species in 53 botanical families (Genin 2010). This detrimental disease is found globally and is caused by various strains of R. solanacearum; one example is the K60 strain which is found in the United States. Bacterial pathogens like R. solanacearum use their type III secretion system (T3SS) to suppress host immune responses and cause disease. T3SS is composed of a needle-like structure that pierces the host cell wall and secretes type III effector (T3E) proteins into the host cell. The function of the T3Es in the K60 strain is not well understood. A small list of K60 T3E proteins was selected to be studied; the first step in this experiment is to determine the subcellular localization of these T3Es. A green fluorescent protein (GFP) was attached to the C-terminus of the individual T3E, and was transiently expressed in two systems: the hairy root system in tomato and the Nicotiana benthamiana leaf system. The subcellular localization of each T3E was observed with the Zeiss LSM 880 Upright Confocal Microscope. Preliminary results suggest that two T3Es, RsK60-8 and RsK60-17, localize at the plasma membrane, RsK60-15 at the nucleus, and two, RsK60-3 and RsK60-6, localize at actin filaments. Future work will use secretion assays to confirm secretion of the T3Es, as well as yeast two-hybrid and mutant analyses to determine the interacting partners and function of the individual T3Es.

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Ralstonia solanacearum differentially colonizes roots of resistant and susceptible tomato plants

  Phytopathology

• The Subcellular Localization of Ralstonia solanacearum K60 Type III Effectors

  APSNET

  Ralstonia solanacearum is a soil-borne bacterial pathogen that causes Bacterial Wilt disease in over 200 plant species in 53 botanical families (Genin 2010). This detrimental disease is found globally and is caused by various strains of R. solanacearum; one example is the K60 strain which is found in the United States. Bacterial pathogens like R. solanacearum use their type III secretion system (T3SS) to suppress host immune responses and cause disease. T3SS is composed of a needle-like structure that pierces the host cell wall and secretes type III effector (T3E) proteins into the host cell. The function of the T3Es in the K60 strain is not well understood. A small list of K60 T3E proteins was selected to be studied; the first step in this experiment is to determine the subcellular localization of these T3Es. A green fluorescent protein (GFP) was attached to the C-terminus of the individual T3E, and was transiently expressed in two systems: the hairy root system in tomato and the Nicotiana benthamiana leaf system. The subcellular localization of each T3E was observed with the Zeiss LSM 880 Upright Confocal Microscope. Preliminary results suggest that two T3Es, RsK60-8 and RsK60-17, localize at the plasma membrane, RsK60-15 at the nucleus, and two, RsK60-3 and RsK60-6, localize at actin filaments. Future work will use secretion assays to confirm secretion of the T3Es, as well as yeast two-hybrid and mutant analyses to determine the interacting partners and function of the individual T3Es.

• A Scanning Electron Microscopy Technique for Viewing Plant-Microbe Interactions at Tissue and Cell-Type Resolution

  Phytopathology

  Observing pathogen colonization and localization within specific plant tissues is a critical component of plant pathology research. High resolution imaging, in which the researcher can clearly view the plant pathogen interacting with a specific plant cell, is needed to enhance our understanding of pathogen lifestyle and virulence mechanisms. However, it can be challenging to find the pathogen along the plant surface or in a specific cell type. Because of the time-consuming and expensive nature of high resolution microscopy, techniques that allow a researcher to find a region of pathogen colonization more quickly at low resolution and subsequently move to a high-resolution microscope for detailed observation are needed. Here we present paraffin scanning electron microscopy (PSEM), a technique in which paraffin embedded samples are first sectioned to identify a region of interest. Subsequently the same block is recut, deparaffinized, and used in scanning electron microscopy to generate high resolution images of plant-pathogen interactions in specific plant cell types. This method has several additional advantages over traditional SEM techniques, including reduced noise and better image quality. Here we use this technique to show that Fusarium oxysporum f. sp. lycopersici colonization is restricted in resistant Solanum pimpinellifolium, and that PSEM works well in additional pathosystems including maize leaves and Clavibacter michiganensis subsp. nebraskensis, and Arabidopsis leaves and Pseudomonas syringae.

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Ralstonia solanacearum differentially colonizes roots of resistant and susceptible tomato plants

  Phytopathology

• The Subcellular Localization of Ralstonia solanacearum K60 Type III Effectors

  APSNET

  Ralstonia solanacearum is a soil-borne bacterial pathogen that causes Bacterial Wilt disease in over 200 plant species in 53 botanical families (Genin 2010). This detrimental disease is found globally and is caused by various strains of R. solanacearum; one example is the K60 strain which is found in the United States. Bacterial pathogens like R. solanacearum use their type III secretion system (T3SS) to suppress host immune responses and cause disease. T3SS is composed of a needle-like structure that pierces the host cell wall and secretes type III effector (T3E) proteins into the host cell. The function of the T3Es in the K60 strain is not well understood. A small list of K60 T3E proteins was selected to be studied; the first step in this experiment is to determine the subcellular localization of these T3Es. A green fluorescent protein (GFP) was attached to the C-terminus of the individual T3E, and was transiently expressed in two systems: the hairy root system in tomato and the Nicotiana benthamiana leaf system. The subcellular localization of each T3E was observed with the Zeiss LSM 880 Upright Confocal Microscope. Preliminary results suggest that two T3Es, RsK60-8 and RsK60-17, localize at the plasma membrane, RsK60-15 at the nucleus, and two, RsK60-3 and RsK60-6, localize at actin filaments. Future work will use secretion assays to confirm secretion of the T3Es, as well as yeast two-hybrid and mutant analyses to determine the interacting partners and function of the individual T3Es.

• A Scanning Electron Microscopy Technique for Viewing Plant-Microbe Interactions at Tissue and Cell-Type Resolution

  Phytopathology

  Observing pathogen colonization and localization within specific plant tissues is a critical component of plant pathology research. High resolution imaging, in which the researcher can clearly view the plant pathogen interacting with a specific plant cell, is needed to enhance our understanding of pathogen lifestyle and virulence mechanisms. However, it can be challenging to find the pathogen along the plant surface or in a specific cell type. Because of the time-consuming and expensive nature of high resolution microscopy, techniques that allow a researcher to find a region of pathogen colonization more quickly at low resolution and subsequently move to a high-resolution microscope for detailed observation are needed. Here we present paraffin scanning electron microscopy (PSEM), a technique in which paraffin embedded samples are first sectioned to identify a region of interest. Subsequently the same block is recut, deparaffinized, and used in scanning electron microscopy to generate high resolution images of plant-pathogen interactions in specific plant cell types. This method has several additional advantages over traditional SEM techniques, including reduced noise and better image quality. Here we use this technique to show that Fusarium oxysporum f. sp. lycopersici colonization is restricted in resistant Solanum pimpinellifolium, and that PSEM works well in additional pathosystems including maize leaves and Clavibacter michiganensis subsp. nebraskensis, and Arabidopsis leaves and Pseudomonas syringae.

• Genomics and Phenomics Approaches to Understanding Root-mediated Resistance to Ralstonia solanacearum in Tomato

  APSNET

  Plant roots constantly defend themselves against soilborne pathogens. Although roots are often critical to whole plant resistance, root defense responses are not well understood. Our long-term goal is to decipher the mechanisms of root-mediated resistance to the soilborne bacteria and fungi that cause a large class of root diseases known as vascular wilts. Ralstonia solancearum (Rs), the causal agent of bacterial wilt disease, causes upwards of 90% disease loss during epidemics. Using the tomato – Rs pathosystem as a model, we are exploring the interplay between root development and disease in root-mediated resistance. Light and scanning electron microscopy revealed that bacteria are differentially distributed in tomato root cell types of resistant and susceptible varieties, and that resistant plants delay colonization of the root vasculature. A time course of tomato root global gene expression profiling after Rs infection demonstrated that roots of resistant plants alter auxin pathways after infection. Mutational analyses with tomato mutants with altered auxin pathways revealed the critical nature of auxin in bacterial wilt disease. We have optimized the tomato hairy root system to examine Rs type III effectors in tomato root infection and find effector localization to the nucleus, cytoskeleton, and plasma membrane of tomato roots. Our data suggest that root-mediated resistance operates at multiple scales – from subcellular to cellular and whole organ levels.

• Plant Stem Segmentation Using Fast Ground Truth Generation

  arXiv

• Bacterial wilt disease: Host resistance and pathogen virulence mechanisms

  Contents lists available at ScienceDirect Physiological and Molecular Plant Pathology journal homepage: www.elsevier.com/locate/pmpp

• Ralstonia solanacearum differentially colonizes roots of resistant and susceptible tomato plants

  Phytopathology

• The Subcellular Localization of Ralstonia solanacearum K60 Type III Effectors

  APSNET

  Ralstonia solanacearum is a soil-borne bacterial pathogen that causes Bacterial Wilt disease in over 200 plant species in 53 botanical families (Genin 2010). This detrimental disease is found globally and is caused by various strains of R. solanacearum; one example is the K60 strain which is found in the United States. Bacterial pathogens like R. solanacearum use their type III secretion system (T3SS) to suppress host immune responses and cause disease. T3SS is composed of a needle-like structure that pierces the host cell wall and secretes type III effector (T3E) proteins into the host cell. The function of the T3Es in the K60 strain is not well understood. A small list of K60 T3E proteins was selected to be studied; the first step in this experiment is to determine the subcellular localization of these T3Es. A green fluorescent protein (GFP) was attached to the C-terminus of the individual T3E, and was transiently expressed in two systems: the hairy root system in tomato and the Nicotiana benthamiana leaf system. The subcellular localization of each T3E was observed with the Zeiss LSM 880 Upright Confocal Microscope. Preliminary results suggest that two T3Es, RsK60-8 and RsK60-17, localize at the plasma membrane, RsK60-15 at the nucleus, and two, RsK60-3 and RsK60-6, localize at actin filaments. Future work will use secretion assays to confirm secretion of the T3Es, as well as yeast two-hybrid and mutant analyses to determine the interacting partners and function of the individual T3Es.

• A Scanning Electron Microscopy Technique for Viewing Plant-Microbe Interactions at Tissue and Cell-Type Resolution

  Phytopathology

  Observing pathogen colonization and localization within specific plant tissues is a critical component of plant pathology research. High resolution imaging, in which the researcher can clearly view the plant pathogen interacting with a specific plant cell, is needed to enhance our understanding of pathogen lifestyle and virulence mechanisms. However, it can be challenging to find the pathogen along the plant surface or in a specific cell type. Because of the time-consuming and expensive nature of high resolution microscopy, techniques that allow a researcher to find a region of pathogen colonization more quickly at low resolution and subsequently move to a high-resolution microscope for detailed observation are needed. Here we present paraffin scanning electron microscopy (PSEM), a technique in which paraffin embedded samples are first sectioned to identify a region of interest. Subsequently the same block is recut, deparaffinized, and used in scanning electron microscopy to generate high resolution images of plant-pathogen interactions in specific plant cell types. This method has several additional advantages over traditional SEM techniques, including reduced noise and better image quality. Here we use this technique to show that Fusarium oxysporum f. sp. lycopersici colonization is restricted in resistant Solanum pimpinellifolium, and that PSEM works well in additional pathosystems including maize leaves and Clavibacter michiganensis subsp. nebraskensis, and Arabidopsis leaves and Pseudomonas syringae.

• Genomics and Phenomics Approaches to Understanding Root-mediated Resistance to Ralstonia solanacearum in Tomato

  APSNET

  Plant roots constantly defend themselves against soilborne pathogens. Although roots are often critical to whole plant resistance, root defense responses are not well understood. Our long-term goal is to decipher the mechanisms of root-mediated resistance to the soilborne bacteria and fungi that cause a large class of root diseases known as vascular wilts. Ralstonia solancearum (Rs), the causal agent of bacterial wilt disease, causes upwards of 90% disease loss during epidemics. Using the tomato – Rs pathosystem as a model, we are exploring the interplay between root development and disease in root-mediated resistance. Light and scanning electron microscopy revealed that bacteria are differentially distributed in tomato root cell types of resistant and susceptible varieties, and that resistant plants delay colonization of the root vasculature. A time course of tomato root global gene expression profiling after Rs infection demonstrated that roots of resistant plants alter auxin pathways after infection. Mutational analyses with tomato mutants with altered auxin pathways revealed the critical nature of auxin in bacterial wilt disease. We have optimized the tomato hairy root system to examine Rs type III effectors in tomato root infection and find effector localization to the nucleus, cytoskeleton, and plasma membrane of tomato roots. Our data suggest that root-mediated resistance operates at multiple scales – from subcellular to cellular and whole organ levels.

• A biomimetic platform for studying root-environment interaction

  Plant and Soil

  Microstructure plays an important role in biological systems. Microstructural features are critical in the interaction between two biological organisms, for example, a microorganism and the surface of a plant. However, isolating the structural effect of the interaction from all other parameters is challenging when working directly with the natural system. Replicating microstructure of leaves was recently shown to be a powerful research tool for studying leaf-environment interaction. However, no such tool exists for roots. Roots present a special challenge because of their delicacy (specifically of root hairs) and their 3D structure. We aim at developing such a tool for roots.