RESUMEN
Invasive microbes causing diseases such as sudden oak death negatively affect ecosystems and economies around the world. The deployment of resistant genotypes for combating introduced diseases typically relies on breeding programs that can take decades to complete. To demonstrate how this process can be accelerated, we employed a genome-wide association mapping of ca 1,000 resequenced Populus trichocarpa trees individually challenged with Sphaerulina musiva, an invasive fungal pathogen. Among significant associations, three loci associated with resistance were identified and predicted to encode one putative membrane-bound L-type receptor-like kinase and two receptor-like proteins. A susceptibility-associated locus was predicted to encode a putative G-type D-mannose-binding receptor-like kinase. Multiple lines of evidence, including allele analysis, transcriptomics, binding assays, and overexpression, support the hypothesized function of these candidate genes in the P. trichocarpa response to S. musiva.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Interacciones Huésped-Patógeno/genética , Enfermedades de las Plantas/genética , Proteínas de Plantas/genética , Populus/genética , Saccharomycetales/patogenicidad , Transcriptoma , Alelos , Mapeo Cromosómico , Cromosomas de las Plantas/química , Resistencia a la Enfermedad/genética , Perfilación de la Expresión Génica , Sitios Genéticos , Interacciones Huésped-Patógeno/inmunología , Lectina de Unión a Manosa/genética , Lectina de Unión a Manosa/inmunología , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta/genética , Proteínas de Plantas/inmunología , Populus/inmunología , Populus/microbiología , Proteínas Quinasas/genética , Proteínas Quinasas/inmunología , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/inmunología , Saccharomycetales/fisiologíaRESUMEN
Sphaerulina musiva, the causal agent of Septoria leaf spot and stem canker, is responsible for mortality and yield loss in Populus plantations. However, little is known about the mode of infection and the mechanisms of resistance in this pathosystem. To characterize these phenomena, microscopic, biochemical, and transcriptome comparisons were performed between leaves of moderately resistant and susceptible genotypes of Populus inoculated with S. musiva conidia. Using scanning electron, cryofracture, and laser-scanning confocal microscopy, the infection and colonization of Populus leaves by S. musiva were examined across five time points (48 h, 96 h, 1 week, 2 weeks, and 3 weeks). The infection process was similar regardless of the host genotype. Differences in host colonization between susceptible and moderately resistant genotypes were apparent by 1 week postinoculation. However, the germination of conidia was greater on the susceptible than on the moderately resistant genotype (P < 0.008). Diaminobenzidine staining, a measure of hydrogen peroxide accumulation, was different (P < 0.001) between the host genotypes by 2 weeks postinoculation. Transcriptome differences between genotypes indicated that the speed and amplitude of the defense response were faster and more extensive in the moderately resistant genotype. Changes in gene expression support the microscopic and biochemical observations.
Asunto(s)
Ascomicetos , Resistencia a la Enfermedad , Populus , Ascomicetos/fisiología , Resistencia a la Enfermedad/genética , Genotipo , Enfermedades de las Plantas/microbiología , Hojas de la Planta/microbiología , Populus/genética , Populus/microbiología , TranscriptomaRESUMEN
Fusarium solani species complex (FSSC) 11 is the primary phylogenetic species of FSSC causing root rot in soybean in the north-central United States. A polymerase chain reaction (PCR)-based assay was developed to identify and differentiate FSSC 11 from the less aggressive FSSC 5 and other Fusarium and Pythium spp. associated with soybean roots. The primer set FSSC11-F and FSSC11-R designed from the RNA polymerase second largest subunit gene yielded the expected amplicon of about 900 bp with DNA from all 22 FSSC 11 isolates tested in PCR. However, it did not produce an amplicon with DNA from 29 isolates of FSSC 5, seven other Fusarium spp., three Pythium spp., and soybean tested in PCR. Furthermore, the primer set successfully detected FSSC 11 from a DNA mixture containing the DNA of FSSC 11, FSSC 5, other Fusarium spp., and soybean. The primer set also detected FSSC 11 from both soil and soybean roots. Additionally, the prevalence of FSSC 11 in soybean roots was determined in five fields in North Dakota by both a culture-independent PCR approach with FSSC11-F and FSSC11-R and a culture-dependent approach. Results from both the culture-dependent and culture-independent approaches with FSSC11-F and FSSC11-R were consistent and revealed the presence of the FSSC 11 in three of five fields sampled.