Phytophthora Infestans (Mont.) de Bary. I. Host-pathogen specificity and resistance components
The molecular identity of Phytophthora infestans strains infectingpotatoes in the Toluca Valley has been documented. Nevertheless,the relationship of the P. infestans genotypes to the hosts geneticresistance is unclear. In order to identify potential host-pathogenspecificity, isolates of the oomyce...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2006 |
| País: | México |
| Institución: | Universidad Michoacana de San Nicolás de Hidalgo |
| Repositorio: | Redalyc-UMSNH |
| OAI Identifier: | oai:redalyc.org:30240206 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=30240206 |
| Access Level: | acceso abierto |
| Palabra clave: | Agrociencias host isozymes Compatibility genetic resistance metalaxyl resistance |
| Sumario: | The molecular identity of Phytophthora infestans strains infectingpotatoes in the Toluca Valley has been documented. Nevertheless,the relationship of the P. infestans genotypes to the hosts geneticresistance is unclear. In order to identify potential host-pathogenspecificity, isolates of the oomycete obtained from five potatovarieties with differing levels of disease resistance were comparedregarding mating type (MT), isozyme genotype for glucose-6-phosphate isomerase (Gpi) and peptidase (Pep), and sensitivity tometalaxyl. Also, host resistance components and specificity on thehost-pathogen interaction were assessed twice in detached leavesin the laboratory and once in attached leaves in the greenhouse forthree of the varieties. No mating type predominated relative to hostgenetic resistance (frequency of A1:A2; Alpha, susceptible: 1:1.6;Rosita, resistant: 1:0.75; Norteña, resistant: 1:0.9; Monserrat,resistant: 1:2; Michoacán, resistant: 1:0.20). Eighteen MT-isozymecombinations were identified from 97 isolates. All of them havebeen previously reported. The most common multilocus genotypes(MT, Gpi, and Pep) were A1, 86/100, 100/100 (37% of the wholepopulation) and A2, 86/100, 100/100 (14%). Both genotypesrepresented 66% of the P. infestans population obtained fromcvs. Michoacán and Monserrat. The level of metalaxyl sensitivitywas lower relative to the levels reported in previous studies. Arelationship between frequency of pathogen genotypes and level ofhost genetic resistance was not observed. The isolate from Rositawas the most aggressive. It resulted in the largest lesion area inthe laboratory and in the greenhouse, and showed the highestsporulation in the greenhouse. The isolate from Alpha, whichshowed the highest sporulation in the laboratory, was second insporulation under greenhouse conditions. Aggressiveness washigher in isolates obtained from resistant varieties and onlylimited host-pathogen specificity was observed in cvs. Alpha andRosita. Suppression of lesion area and sporulation were the hostresistance components identified only for the variety Norteña. |
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