Our study aims to utilize untargeted metabolomics to identify
plant metabolites involved in immune responses. Plant bacterial
pathogens cause devastating diseases in a large variety of host
plants. Plants rely on systemic signals emanating from infection
sites through a process called systemic acquired resistance (SAR),
a plant immune response that improves immunity of systemic tissues after prior exposure to a pathogen [8]. Stomata, pores on leaf
surfaces, are formed by pairs of guard cells that recognize pathogens via recognition receptors. Stomata are common entry sites for
pathogenic bacteria, and the specialized guard cells control opening
and closure in response to environmental conditions. Stomatal
closure, a local response to bacterial pathogens [9], is linked to
salicylic acid (SA), the hormone that controls SAR. To date, the
effect of SAR specifically on guard cells is unknown. Our research
shows that this stomatal response to pathogens is altered in uninfected systemic leaves by long distance SAR immune responses.
Here we used an untargeted metabolomic platform to identify
SAR signaling mechanisms specific for guard cells. Specifically, we
profiled metabolite differences between guard cells of systemic
leaves during SAR response in wild-type Columbia (Col-0) Arabidopsis. Pseudomonas syringae pv. tomato DC3000 (Pst) is the
model plant pathogen that has been used extensively to study
pathogen infection in numerous host plants including tomato and
Arabidopsis thaliana. Arabidopsis, a reference dicot species with a
fully sequenced genome and rich genetic resources, provides an
ideal study system to understand how plants can be modified to
improve their response to bacterial pathogens.
2 Materials
2.1 Bacterial
Treatment of Plants
1. Five-week-old Arabidopsis plants grown in short-day (light
8 h/dark16h) conditions. The light intensity is 160 μmol/m
2 s.
2. Pst DC3000 in water (OD600 ¼ 0.02).
3. 10 mM MgCl 2 .
4. Needless syringe.
2.2 Harvesting of
Guard Cell Samples
1. Wild-type Arabidopsis Columbia (Col-0) ecotype systemic
leaves.
2. Blender.
3. Ice water.
4. Nylon mesh—pore size of the 200 μm.
5. Liquid nitrogen.
6. Fluorescein diacetate and neutral red dye.
416
Lisa David et al.
plant metabolites involved in immune responses. Plant bacterial
pathogens cause devastating diseases in a large variety of host
plants. Plants rely on systemic signals emanating from infection
sites through a process called systemic acquired resistance (SAR),
a plant immune response that improves immunity of systemic tissues after prior exposure to a pathogen [8]. Stomata, pores on leaf
surfaces, are formed by pairs of guard cells that recognize pathogens via recognition receptors. Stomata are common entry sites for
pathogenic bacteria, and the specialized guard cells control opening
and closure in response to environmental conditions. Stomatal
closure, a local response to bacterial pathogens [9], is linked to
salicylic acid (SA), the hormone that controls SAR. To date, the
effect of SAR specifically on guard cells is unknown. Our research
shows that this stomatal response to pathogens is altered in uninfected systemic leaves by long distance SAR immune responses.
Here we used an untargeted metabolomic platform to identify
SAR signaling mechanisms specific for guard cells. Specifically, we
profiled metabolite differences between guard cells of systemic
leaves during SAR response in wild-type Columbia (Col-0) Arabidopsis. Pseudomonas syringae pv. tomato DC3000 (Pst) is the
model plant pathogen that has been used extensively to study
pathogen infection in numerous host plants including tomato and
Arabidopsis thaliana. Arabidopsis, a reference dicot species with a
fully sequenced genome and rich genetic resources, provides an
ideal study system to understand how plants can be modified to
improve their response to bacterial pathogens.
2 Materials
2.1 Bacterial
Treatment of Plants
1. Five-week-old Arabidopsis plants grown in short-day (light
8 h/dark16h) conditions. The light intensity is 160 μmol/m
2 s.
2. Pst DC3000 in water (OD600 ¼ 0.02).
3. 10 mM MgCl 2 .
4. Needless syringe.
2.2 Harvesting of
Guard Cell Samples
1. Wild-type Arabidopsis Columbia (Col-0) ecotype systemic
leaves.
2. Blender.
3. Ice water.
4. Nylon mesh—pore size of the 200 μm.
5. Liquid nitrogen.
6. Fluorescein diacetate and neutral red dye.
416
Lisa David et al.