Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea
Barley plants carrying a mutation in the Mlo (barley [Hordeum vulgare L.] cultivar Ingrid) locus conferring a durable resistance against powdery mildew are hypersusceptible to the rice blast fungus Magnaporthe grisea. It has been speculated that a functional Mlo gene is required for the expression o...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
2003-02-01
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| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI.2003.16.2.107 |
| _version_ | 1811291299069820928 |
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| author | Birgit Jarosch Marcus Jansen Ulrich Schaffrath |
| author_facet | Birgit Jarosch Marcus Jansen Ulrich Schaffrath |
| author_sort | Birgit Jarosch |
| collection | DOAJ |
| description | Barley plants carrying a mutation in the Mlo (barley [Hordeum vulgare L.] cultivar Ingrid) locus conferring a durable resistance against powdery mildew are hypersusceptible to the rice blast fungus Magnaporthe grisea. It has been speculated that a functional Mlo gene is required for the expression of basic pathogen resistance and that the loss of Mlo function mediating powdery mildew resistance is an exception for this particular disease. Here, we report that the onset of acquired resistance (AR) after chemical as well as biological treatments is sufficient to overcome the hypersusceptible phenotype of backcross line BCIngridmlo5 (mlo) barley plants against M. grisea. Moreover, even barley plants bearing a functional Mlo gene and thus showing a moderate infection phenotype against rice blast exhibit a further enhanced resistance after induction of AR. Cytological investigations reveal that acquired resistance in mlo genotypes is manifested by the restoration of the ability to form an effective papilla at sites of attempted penetration, similarly to wild-type Mlo plants. In addition, the rate of effective papillae formation in Mlo plants was further enhanced after the onset of AR. These results demonstrate that treatments leading to the AR state in barley function independently of the Mlo/mlo phenotype and suggest that the Mlo protein is not a component of the AR signaling network. Moreover, it seems that only concomitant action of Mlo together with AR permits high level resistance in barley against blast. Higher steady state levels of PR1 and barley chemically induced mRNA correlate with higher disease severity rather than with the degree of resistance observed in this particular interaction. |
| first_indexed | 2024-04-13T04:27:18Z |
| format | Article |
| id | doaj.art-f55a984282c94ecbaeef4f3a50d95d32 |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-04-13T04:27:18Z |
| publishDate | 2003-02-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-f55a984282c94ecbaeef4f3a50d95d322022-12-22T03:02:28ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062003-02-0116210711410.1094/MPMI.2003.16.2.107Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe griseaBirgit JaroschMarcus JansenUlrich SchaffrathBarley plants carrying a mutation in the Mlo (barley [Hordeum vulgare L.] cultivar Ingrid) locus conferring a durable resistance against powdery mildew are hypersusceptible to the rice blast fungus Magnaporthe grisea. It has been speculated that a functional Mlo gene is required for the expression of basic pathogen resistance and that the loss of Mlo function mediating powdery mildew resistance is an exception for this particular disease. Here, we report that the onset of acquired resistance (AR) after chemical as well as biological treatments is sufficient to overcome the hypersusceptible phenotype of backcross line BCIngridmlo5 (mlo) barley plants against M. grisea. Moreover, even barley plants bearing a functional Mlo gene and thus showing a moderate infection phenotype against rice blast exhibit a further enhanced resistance after induction of AR. Cytological investigations reveal that acquired resistance in mlo genotypes is manifested by the restoration of the ability to form an effective papilla at sites of attempted penetration, similarly to wild-type Mlo plants. In addition, the rate of effective papillae formation in Mlo plants was further enhanced after the onset of AR. These results demonstrate that treatments leading to the AR state in barley function independently of the Mlo/mlo phenotype and suggest that the Mlo protein is not a component of the AR signaling network. Moreover, it seems that only concomitant action of Mlo together with AR permits high level resistance in barley against blast. Higher steady state levels of PR1 and barley chemically induced mRNA correlate with higher disease severity rather than with the degree of resistance observed in this particular interaction.https://apsjournals.apsnet.org/doi/10.1094/MPMI.2003.16.2.107 |
| spellingShingle | Birgit Jarosch Marcus Jansen Ulrich Schaffrath Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea Molecular Plant-Microbe Interactions |
| title | Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea |
| title_full | Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea |
| title_fullStr | Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea |
| title_full_unstemmed | Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea |
| title_short | Acquired Resistance Functions in mlo Barley, Which Is Hypersusceptible to Magnaporthe grisea |
| title_sort | acquired resistance functions in mlo barley which is hypersusceptible to magnaporthe grisea |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI.2003.16.2.107 |
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