Introduction: Botrytis cinerea (teleomorph: Botryotinia fuckeliana) is an airborne plant pathogen with a necrotrophic lifestyle attacking over 200 crop hosts worldwide. Although there are fungicides for its control, many classes of fungicides have failed due to its genetic plasticity. It has become an important model for molecular study of necrotrophic fungi. Taxonomy: Kingdom: Fungi, phylum: Ascomycota, subphylum: Pezizomycotina, class: Leotiomycetes, order: Helotiales, family: Sclerotiniaceae, genus: Botryotinia. Host range and symptoms: Over 200 mainly dicotyledonous plant species, including important protein, oil, fibre and horticultural crops, are affected in temperate and subtropical regions. It can cause soft rotting of all aerial plant parts, and rotting of vegetables, fruits and flowers post-harvest to produce prolific grey conidiophores and (macro)conidia typical of the disease. Pathogenicity: B. cinerea produces a range of cell-wall-degrading enzymes, toxins and other low-molecular-weight compounds such as oxalic acid. New evidence suggests that the pathogen triggers the host to induce programmed cell death as an attack strategy. Resistance: There are few examples of robust genetic host resistance, but recent work has identified quantitative trait loci in tomato that offer new approaches for stable polygenic resistance in future.

Botrytis cinerea: the cause of grey mould disease

The hypersensitive response (HR) of plants resistant to microbial pathogens involves a complex form of programmed cell death (PCD) that differs from developmental PCD in its consistent association with the induction of local and systemic defence responses. Hypersensitive cell death is commonly controlled by direct or indirect interactions between pathogen avirulence gene products and those of plant resistance genes and it can be the result of multiple signalling pathways. Ion fluxes and the generation of reactive oxygen species commonly precede cell death, but a direct involvement of the latter seems to vary with the plant-pathogen combination. Protein synthesis, an intact actin cytoskeleton and salicylic acid also seem necessary for cell death induction. Cytological studies suggest that the actual mode and sequence of dismantling the cell contents varies among plant-parasite systems although there may be a universal involvement of cysteine proteases. It seems likely that cell death within the HR acts more as a signal to the rest of the plant rather than as a direct defence mechanism.

Hypersensitive response-related death.

Plants are equipped with an array of defense mechanisms to protect themselves against attack by herbivorous insects and microbial pathogens. Some of these defense mechanisms are preexisting, whereas others are only activated upon insect or pathogen invasion. Induced defense responses entail fitness

Cross Talk in Defense Signaling

https://www.bioinf.uni-leipzig.de/Leere/SS10/Praktikum/Uelker04_WRKY.pdf

WRKY transcription factors: from DNA binding towards biological function

WRKY proteins are a recently identified class of DNA-binding proteins that recognize the TTGAC(C/T) W-box elements found in the promoters of a large number of plant defense-related genes. With oligo molecules containing the W-box sequences as probes, we detected a number of WRKY DNA-binding activities in Arabidopsis that were induced by salicylic acid (SA). Search of the Arabidopsis genome identifies 72 genes encoding proteins characteristic of WRKY DNA-binding transcription factors that can be divided into three groups based on the number and structures of their WRKY zinc-finger motifs. Northern blotting analysis revealed that 49 of the 72 AtWRKY genes were differentially regulated in the plants infected by an avirulent strain of the bacterial pathogen Pseudomonas syringae or treated by SA. These pathogen- and/or SA-regulated WRKY genes can be further categorized into groups based on their expression patterns in both wild-type plants and mutants defective in defense signaling pathways. Inspection of the 5' sequences upstream of the predicated translation start sites revealed a substantial enrichment of W boxes in the promoters of pathogen- and/or SA-regulated Arabidopsis WRKY genes. These results suggest that defense-regulated expression of WRKY genes involves extensive transcriptional activation and repression by its own members of the transcription factor superfamily.

Expression profiles of the Arabidopsis WRKY gene superfamily during plant defense response.

Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as "safe fungicides". This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use.

https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-95-1368

Induced Resistance for Plant Disease Control: Maximizing the Efficacy of Resistance Elicitors

A potato gene encoding a putative WRKY protein was isolated from a cDNA library enriched by suppression subtractive hybridization for sequences upregulated 1 h post-inoculation with Erwinia carotovora subsp. atroseptica. The cDNA encodes a putative polypeptide of 172 amino acids, containing a single WRKY domain with a zinc finger motif and preceded by a potential nuclear localization site. St-WRKY1 was strongly upregulated in compatible, but only weakly in incompatible, interactions with Phytophthora infestans where, in all cases, it was coregulated with class I endochitinase, associating its expression with a known defense response. Whereas St-WRKY1 was strongly induced by E. carotovora culture filtrate (CF), confirming it to be an elicitor-induced gene, no such induction was detected after treatment with salicylic acid, methyl jasmonate, ethylene, or wounding. St-WRKY1 was upregulated by treatment of potato leaves with CFs from recombinant Escherichia coli containing plasmids expressing E. carotovora pe...

/pdf/a-potato-gene-encoding-a-wrky-like-transcription-factor-is-4ync3r445u.pdf

A potato gene encoding a WRKY-like transcription factor is induced in interactions with Erwinia carotovora subsp. atroseptica and Phytophthora infestans and is coregulated with class I endochitinase expression.

Induced resistance offers the prospect of broad spectrum, long-lasting and potentially environmentally-benign disease and pest control in plants. Induced Resistance for Plant Defense 2e provides a comprehensive account of the subject, encompassing the underlying science and methodology, as well as research on application of the phenomenon in practice. The second edition of this important book includes updated coverage of cellular aspects of induced resistance, including signalling and defenses, costs and trade-offs associated with the expression of induced resistance, research aimed at integrating induced resistance into crop protection practice, and induced resistance from a commercial perspective. Current thinking on how beneficial microbes induce resistance in plants has been included in the second edition. The 14 chapters in this book have been written by internationally-respected researchers and edited by three editors with considerable experience of working on induced resistance. Like its predecessor, the second edition of Induced Resistance for Plant Defense will be of great interest to plant pathologists, plant cell and molecular biologists, agricultural scientists, crop protection specialists, and personnel in the agrochemical industry. All libraries in universities and research establishments where biological, agricultural, horticultural and forest sciences are studied and taught should have copies of this book on their shelves.

Induced resistance for plant defence: a sustainable approach to crop protection

Suppression subtractive hybridization (SSH) was used to generate a cDNA library enriched for sequences induced in a late-blight-resistant potato cultivar undergoing the hypersensitive response (HR). Of 100 partial cDNA sequences submitted to international DNA and protein data bases, 42 showed similarity to 35 genes, of which 31 were from plants. Of these, 13 were previously characterized as either defense-, stress-, or senescence-associated. One sequence matched (75 to 81%) all known serine palmitoyltransferases (SPTs) at the protein level. SPT catalyzes the first committed step in the synthesis of sphingolipids, important signaling molecules involved in cell differentiation and apoptosis. Putative products of other genes identified here may play a role in programmed cell death, including protein degradation, DNA degradation, metal ion chelation, and signal transduction. cDNA-amplified fragment length polymorphism was used to confirm differential expression of sequences isolated by SSH.

Isolation of Potato Genes That Are Induced During an Early Stage of the Hypersensitive Response to Phytophthora infestans

https://leseprobe.buch.de/images-adb/ed/71/ed711994-070a-4983-b030-6259f767a8c1.pdf

Gary D. Lyon

Papers

Induced Resistance for Plant Disease Control: Maximizing the Efficacy of Resistance Elicitors

A potato gene encoding a WRKY-like transcription factor is induced in interactions with Erwinia carotovora subsp. atroseptica and Phytophthora infestans and is coregulated with class I endochitinase expression.

Induced resistance for plant defence: a sustainable approach to crop protection

Isolation of Potato Genes That Are Induced During an Early Stage of the Hypersensitive Response to Phytophthora infestans

Induced Resistance for Plant Defence