RESUMO
The use of resistant cultivars is one of the most practical and cost-efficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident.
Assuntos
Cicer/microbiologia , Fusarium/patogenicidade , Filogenia , Evolução Biológica , Impressões Digitais de DNA , Fusarium/classificação , Fusarium/genética , Marcadores Genéticos , Variação Genética , Fator 1 de Elongação de Peptídeos/classificação , Fator 1 de Elongação de Peptídeos/genética , Doenças das Plantas/microbiologia , Técnica de Amplificação ao Acaso de DNA Polimórfico , Virulência/genéticaRESUMO
The use of resistant cultivars is one of the most practical and costefficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident (AU)
La utilización de cultivares resistentes es una de las estrategias más prácticas y económicas para el control de las enfermedades de las plantas. No obstante, la eficiencia de los cultivares resistentes en dicho control está limitada por la variabilidad patogénica en las poblaciones de los patógenos. El conocimiento de la historia y el potencial evolutivo de las poblaciones de los patógenos puede ayudarnos a optimizar el uso de los genes de resistencia contra enfermedades, independientemente de la estrategia de mejora genética del huésped empleada para su desarrollo. En esta revisión examinamos la diversidad de los fenotipos de virulencia en Fusarium oxysporum f.sp. ciceris, el agente causal de la Fusariosis vascular del garbanzo, analizamos la variabilidad genética intra- e interfenotípica, e inferimos la relación filogenética existente entre las ocho razas patógénicas conocidas de este hongo. La filogenia intraespecífica inferida muestra que cada una de estas ocho razas constituye un linaje monofilético. Además, las razas virulentas sobre los cultivares resistentes de garbanzo han adquirido esta capacidad según un modelo gradual simple, con pocas ganancias o pérdidas paralelas de virulencia. A pesar de que existen cultivares de garbanzo resistentes a la Fusariosis vascular, la utilización restringida de ellas realizada hasta ahora permite que la adquisición gradual de virulencia sea aún claramente perceptible (AU)
