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Nectar- and stigma exudate-specific expression of an acidic chitinase could partially protect certain apple cultivars against fire blight disease.
- Source :
-
Planta [Planta] 2019 Nov 28; Vol. 251 (1), pp. 20. Date of Electronic Publication: 2019 Nov 28. - Publication Year :
- 2019
-
Abstract
- Main Conclusion: Certain apple cultivars accumulate to high levels in their nectar and stigma exudate an acidic chitinase III protein that can protect against pathogens including fire blight disease causing Erwinia amylovora. To prevent microbial infections, flower nectars and stigma exudates contain various antimicrobial compounds. Erwinia amylovora, the causing bacterium of the devastating fire blight apple disease, is the model pathogen that multiplies in flower secretions and infects through the nectaries. Although Erwinia-resistant apples are not available, certain cultivars are tolerant. It was reported that in flower infection assay, the 'Freedom' cultivar was Erwinia tolerant, while the 'Jonagold' cultivar was susceptible. We hypothesized that differences in the nectar protein compositions lead to different susceptibility. Indeed, we found that an acidic chitinase III protein (Machi3-1) selectively accumulates to very high levels in the nectar and the stigma exudate of the 'Freedom' cultivar. We show that three different Machi3-1 alleles exist in apple cultivars and that only the 5B-Machi3-1 allele expresses the Machi3-1 protein in the nectar and the stigma exudate. We demonstrate that the 5B-Machi3-1 allele was introgressed from the Malus floribunda 821 clone into different apple cultivars including the 'Freedom'. Our data suggest that MYB-binding site containing repeats of the 5B-Machi3-1 promoter is responsible for the strong nectar- and stigma exudate-specific expression. As we found that in vitro, the Machi3-1 protein impairs growth and biofilm formation of Erwinia at physiological concentration, we propose that the Machi3-1 protein could partially protect 5B-Machi3-1 allele containing cultivars against Erwinia by inhibiting the multiplication and biofilm formation of the pathogen in the stigma exudate and in the nectar.
- Subjects :
- Alleles
Amino Acid Sequence
Anti-Bacterial Agents pharmacology
Biofilms drug effects
Biofilms growth & development
Chitinases chemistry
Disease Resistance
Erwinia amylovora drug effects
Erwinia amylovora growth & development
Gene Expression Regulation, Plant drug effects
Malus drug effects
Malus genetics
Organ Specificity
Plant Proteins chemistry
Plant Proteins metabolism
Promoter Regions, Genetic genetics
RNA, Messenger genetics
RNA, Messenger metabolism
Nicotiana genetics
Chitinases metabolism
Erwinia amylovora physiology
Flowers metabolism
Malus enzymology
Malus microbiology
Plant Diseases microbiology
Plant Exudates metabolism
Plant Nectar metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1432-2048
- Volume :
- 251
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Planta
- Publication Type :
- Academic Journal
- Accession number :
- 31781986
- Full Text :
- https://doi.org/10.1007/s00425-019-03303-2