- THIS ARTICLE
- Full Text (PDF)
- Alert me when this article is cited
- Alert me if a correction is posted
- SERVICES
- Similar articles in this journal
- Similar articles in PubMed
- Alert me to new issues of the journal
- Download to citation manager
- Reprints & Permissions
- CITING ARTICLES
- Citing Articles via HighWire
- Citing Articles via Google Scholar
- GOOGLE SCHOLAR
- Articles by Okubara, P. A.
- Articles by Michelmore, R. W.
- Search for Related Content
- PUBMED
- PubMed Citation
- Articles by Okubara, P. A.
- Articles by Michelmore, R. W.
Genetics, Vol 137, 867-874, Copyright © 1994
INVESTIGATIONS |
Mutants of Downy Mildew Resistance in Lactuca sativa (Lettuce)
P. A. Okubara, P. A. Anderson, O. E. Ochoa and R. W. Michelmore
Department of Vegetable Crops, University of California, Davis, California 95616
As part of our investigation of disease resistance in lettuce, we generated mutants that have lost resistance to Bremia lactucae, the casual fungus of downy mildew. Using a rapid and reliable screen, we identified 16 distinct mutants of Latuca sativa that have lost activity of one of four different downy mildew resistance genes (Dm). In all mutants, only a single Dm specificity was affected. Genetic analysis indicated that the lesions segregated as single, recessive mutations at the Dm loci. Dm3 was inactivated in nine of the mutants. One of five Dm1 mutants was selected from a population of untreated seeds and therefore carried a spontaneous mutation. All other Dm1, Dm3, Dm5/8 and Dm7 mutants were derived from {gamma}- or fast neutron-irradiated seed. In two separate Dm1 mutants and in each of the eight Dm3 mutants analyzed, at least one closely linked molecular marker was absent. Also, high molecular weight genomic DNA fragments that hybridized to a tightly linked molecular marker in wild type were either missing entirely or were truncated in two of the Dm3 mutants, providing additional evidence that deletions had occurred in these mutants. Absence of mutations at loci epistatic to the Dm genes suggested that such loci were either members of multigene families, were critical for plant survival, or encoded components of duplicated pathways for resistance; alternatively, the genes determining downy mildew resistance might be limited to the Dm loci.
This article has been cited by other articles:
 |
|
 |
|
  D. B. Chin, R. Arroyo-Garcia, O. E. Ochoa, R. V. Kesseli, D. O. Lavelle, and R. W. Michelmore Recombination and Spontaneous Mutation at the Major Cluster of Resistance Genes in Lettuce (Lactuca sativa) Genetics, February 1, 2001; 157(2): 831 - 849. [Abstract] [Full Text]
|
|
|
|
 |
|
 B. C. Meyers, D. B. Chin, K. A. Shen, S. Sivaramakrishnan, D. O. Lavelle, Z. Zhang, and R. W. Michelmore The Major Resistance Gene Cluster in Lettuce Is Highly Duplicated and Spans Several Megabases PLANT CELL, November 1, 1998; 10(11): 1817 - 1832. [Abstract] [Full Text] [PDF]
|
|