Identification of DIR1-Dependant Cellular Responses in Guard Cell Systemic Acquired Resistance

After localized invasion by bacterial pathogens, systemic acquired resistance (SAR) is induced in uninfected plant tissues, resulting in enhanced defense against a broad range of pathogens. Although SAR requires mobilization of signaling molecules via the plant vasculature, the specific molecular mechanisms remain elusive. The lipid transfer protein defective in induced resistance 1 (DIR1) was identified in Arabidopsis thaliana by screening for mutants that were defective in SAR. Here, we demonstrate that stomatal response to pathogens is altered in systemic leaves by SAR, and this guard cell SAR defense requires DIR1. Using a multi-omics approach, we have determined potential SAR signaling mechanisms specific for guard cells in systemic leaves by profiling metabolite, lipid, and protein differences between guard cells in the wild type and dir1-1 mutant during SAR. We identified two long-chain 18 C and 22 C fatty acids and two 16 C wax esters as putative SAR-related molecules dependent on DIR1. Proteins and metabolites related to amino acid biosynthesis and response to stimulus were also changed in guard cells of dir1-1 compared to the wild type. Identification of guard cell-specific SAR-related molecules may lead to new avenues of genetic modification/molecular breeding for disease-resistant plants.

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Identification of DIR1-dependant cellular responses required for guard cell systemic acquired resistance

10.1101/2021.06.02.446770 ◽

2021 ◽

Author(s):

Lisa David ◽

Jianing Kang ◽

Joshua J Nicklay ◽

Craig Dufresne ◽

Sixue Chen

Keyword(s):

Guard Cell ◽

Molecular Mechanisms ◽

Systemic Acquired Resistance ◽

Lipid Transfer Protein ◽

Acquired Resistance ◽

Guard Cells ◽

Lipid Transfer ◽

Wild Type ◽

Transfer Protein ◽

Uninfected Plant

After localized invasion by bacterial pathogens, systemic acquired resistance (SAR) is induced in uninfected plant tissues, resulting in enhanced defense against a broad range of pathogens. Although SAR requires mobilization of signaling molecules via the plant vasculature, the specific molecular mechanisms remain elusive. The lipid transfer protein-defective in induced resistance 1-1 (DIR1-1) was identified in Arabidopsis thaliana by screening for mutants that were defective in SAR. Here we demonstrate that stomatal response to pathogens is altered in systemic leaves by SAR, and this guard cell SAR defense requires DIR1. Using a multi-omics approach, we have determined potential SAR signaling mechanisms specific for guard cells in systemic leaves by profiling metabolite, lipid, and protein differences between guard cells in wild type and dir1-1 mutant during SAR. We identified two 18C fatty acids and two 16C wax esters as putative SAR-related molecules dependent on DIR1. Proteins and metabolites related to amino acid biosynthesis and response to stimulus were also changed in guard cells of dir1-1 compared to wild type. Identification of guard cell-specific SAR-related molecules may lead to new avenues of genetic modification/molecular breeding for disease resistant plants.

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Multi-Omics Revealed Molecular Mechanisms Underlying Guard Cell Systemic Acquired Resistance

International Journal of Molecular Sciences ◽

10.3390/ijms22010191 ◽

2020 ◽

Vol 22 (1) ◽

pp. 191

Author(s):

Lisa David ◽

Jianing Kang ◽

Daniel Dufresne ◽

Dan Zhu ◽

Sixue Chen

Keyword(s):

Palmitic Acid ◽

Pseudomonas Syringae ◽

Guard Cell ◽

Pathogenic Bacteria ◽

Molecular Mechanisms ◽

Systemic Acquired Resistance ◽

Acquired Resistance ◽

Guard Cells ◽

Local Exposure ◽

Molecular Components

Systemic Acquired Resistance (SAR) improves immunity of plant systemic tissue after local exposure to a pathogen. Guard cells that form stomatal pores on leaf surfaces recognize bacterial pathogens via pattern recognition receptors, such as Flagellin Sensitive 2 (FLS2). However, how SAR affects stomatal immunity is not known. In this study, we aim to reveal molecular mechanisms underlying the guard cell response to SAR using multi-omics of proteins, metabolites and lipids. Arabidopsis plants previously exposed to pathogenic bacteria Pseudomonas syringae pv. tomato DC3000 (Pst) exhibit an altered stomatal response compared to control plants when they are later exposed to the bacteria. Reduced stomatal apertures of SAR primed plants lead to decreased number of bacteria in leaves. Multi-omics has revealed molecular components of SAR response specific to guard cells functions, including potential roles of reactive oxygen species (ROS) and fatty acid signaling. Our results show an increase in palmitic acid and its derivative in the primed guard cells. Palmitic acid may play a role as an activator of FLS2, which initiates stomatal immune response. Improved understanding of how SAR signals affect stomatal immunity can aid biotechnology and marker-based breeding of crops for enhanced disease resistance.

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Redox proteomics of stomatal immunity reveals role of a lipid transfer protein in plant defense

10.1101/2020.05.21.108704 ◽

2020 ◽

Author(s):

Kelly M Balmant ◽

Sheldon R Lawrence ◽

Benjamin V Duong ◽

Fanzhao Zhu ◽

Ning Zhu ◽

...

Keyword(s):

Plant Defense ◽

Lipid Transfer Protein ◽

Guard Cells ◽

Lipid Binding ◽

Lipid Transfer ◽

Redox Proteomics ◽

Transfer Protein ◽

Redox Responsive ◽

Redox Sensors ◽

Thiol Redox

ABSTRACTRedox-based post-translational modifications (PTMs) involving protein cysteine residues as redox sensors are important to various physiological processes. However, little is known about redox-sensitive proteins in guard cells and their functions in stomatal immunity. In this study, we applied an integrative protein labeling method cysTMTRAQ and identified guard cell proteins that were altered by thiol redox PTMs in response to a bacterial flagellin peptide flg22. In total, eight, seven and 20 potential redox-responsive proteins were identified in guard cells treated with flg22 for 15, 30 and 60 min, respectively. The proteins fall into several functional groups including photosynthesis, lipid binding, oxidation-reduction, and defense. Among the proteins, a lipid transfer protein (LTP)-II was confirmed to be redox-responsive and involved in plant resistance to Pseudomonas syringe pv. tomato DC3000. This study not only creates an inventory of potential redox-sensitive proteins in flg22 signal transduction in guard cells, but also highlights the relevance of the lipid transfer protein in plant defense against the bacterial pathogens.Sentence summaryThiol-redox proteomics identified potential redox sensors important in stomatal immunity, and a lipid transfer protein was characterized to function as a redox sensor in plant immune response.

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A second member of the Nicotiana glauca lipid transfer protein gene family, NgLTP2, encodes a divergent and differentially expressed protein

Functional Plant Biology ◽

10.1071/fp05170 ◽

2006 ◽

Vol 33 (2) ◽

pp. 141 ◽

Cited By ~ 3

Author(s):

Kimberly D. Cameron ◽

William A. Moskal ◽

Lawrence B. Smart

Keyword(s):

Gene Family ◽

Cdna Library ◽

Dna Sequences ◽

Guard Cell ◽

Genomic Library ◽

Lipid Transfer Protein ◽

Expression Patterns ◽

Lipid Transfer ◽

Nicotiana Glauca ◽

Transfer Protein

Multiple, highly similar members of the lipid transfer protein (LTP) family have been identified in Nicotiana glauca L. Here we describe four new members of the NgLTP gene family and further characterise one member. Three genes were isolated from a guard cell cDNA library and one (NgLTP2) was isolated from a genomic library. These four NgLTPs, as well as one described previously, NgLTP1, share >83% amino acid similarity, but the deduced protein sequence of NgLTP2 lacks the last five residues compared with other LTPs. Since the DNA sequences of the five genes are nearly identical, techniques based on nucleic acid hybridisation or PCR amplification were not sufficient to resolve the expression of the individual genes with confidence. Therefore, we characterised the expression pattern of NgLTP2, the only NgLTP gene that was not found in the guard cell cDNA library, using an NgLTP2 promoter–GUS reporter assay. GUS activity driven by the NgLTP2 promoter was assayed in three species of transgenic plants as an indicator of the endogenous pattern of expression of this gene. GUS was strongly induced upon wounding, whereas NgLTP1 was induced by drought stress. Sequence analysis of the NgLTP2 promoter revealed cis-acting motifs associated with induction by wounding. Differential expression of the NgLTP gene family, revealed by the different expression patterns of NgLTP1 and NgLTP2, is further evidence that these genes have multiple functions in N. glauca.

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Differential Effectiveness of Microbially Induced Resistance Against Herbivorous Insects in Arabidopsis

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-21-7-0919 ◽

2008 ◽

Vol 21 (7) ◽

pp. 919-930 ◽

Cited By ~ 134

Author(s):

Vivian R. Van Oosten ◽

Natacha Bodenhausen ◽

Philippe Reymond ◽

Johan A. Van Pelt ◽

L. C. Van Loon ◽

...

Keyword(s):

Systemic Acquired Resistance ◽

Pieris Rapae ◽

Lipid Transfer Protein ◽

Acquired Resistance ◽

Parasitic Wasp ◽

Indirect Defense ◽

Systemic Resistance ◽

Lipid Transfer ◽

Generalist Herbivore ◽

Direct Defense

Rhizobacteria–induced systemic resistance (ISR) and pathogen-induced systemic acquired resistance (SAR) have a broad, yet partly distinct, range of effectiveness against pathogenic microorganisms. Here, we investigated the effectiveness of ISR and SAR in Arabidopsis against the tissue-chewing insects Pieris rapae and Spodoptera exigua. Resistance against insects consists of direct defense, such as the production of toxins and feeding deterrents and indirect defense such as the production of plant volatiles that attract carnivorous enemies of the herbivores. Wind-tunnel experiments revealed that ISR and SAR did not affect herbivore-induced attraction of the parasitic wasp Cotesia rubecula (indirect defense). By contrast, ISR and SAR significantly reduced growth and development of the generalist herbivore S. exigua, although not that of the specialist P. rapae. This enhanced direct defense against S. exigua was associated with potentiated expression of the defense-related genes PDF1.2 and HEL. Expression profiling using a dedicated cDNA microarray revealed four additional, differentially primed genes in microbially induced S. exigua-challenged plants, three of which encode a lipid-transfer protein. Together, these results indicate that microbially induced plants are differentially primed for enhanced insect-responsive gene expression that is associated with increased direct defense against the generalist S. exigua but not against the specialist P. rapae.

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