RESUMEN
Pecan scab is a devastating disease that causes damage to pecan (Carya illinoinensis (Wangenh.) K. Koch) fruit and leaves. The disease is caused by the fungus Venturia effusa (G. Winter) and the main management practice for controlling the disease is by application of fungicides at 2-to-3-week intervals throughout the growing season. Besides disease-related yield loss, application of fungicides can result in considerable cost and increases the likelihood of fungicide resistance developing in the pathogen. Resistant cultivars are available for pecan growers; although, in several cases resistance has been overcome as the pathogen adapts to infect resistant hosts. Despite the importance of host resistance in scab management, there is little information regarding the molecular basis of genetic resistance to pecan scab.The purpose of this study was to elucidate mechanisms of natural pecan scab resistance by analyzing transcripts that are differentially expressed in pecan leaf samples from scab resistant and susceptible trees. The leaf samples were collected from trees in a provenance collection orchard that represents the natural range of pecan in the US and Mexico. Trees in the orchard have been exposed to natural scab infections since planting in 1989, and scab ratings were collected over three seasons. Based on this data, ten susceptible trees and ten resistant trees were selected for analysis. RNA-seq data was collected and analyzed for diseased and non-diseased parts of susceptible trees as well as for resistant trees. A total of 313 genes were found to be differentially expressed when comparing resistant and susceptible trees without disease. For susceptible samples showing scab symptoms, 1,454 genes were identified as differentially expressed compared to non-diseased susceptible samples. Many genes involved in pathogen recognition, defense responses, and signal transduction were up-regulated in diseased samples of susceptible trees, whereas differentially expressed genes in pecan scab resistant samples were generally down-regulated compared to non-diseased susceptible samples.Our results provide the first account of candidate genes involved in resistance/susceptibility to pecan scab under natural conditions in a pecan orchard. This information can be used to aid pecan breeding programs and development of biotechnology-based approaches for generating pecan cultivars with more durable scab resistance.
Asunto(s)
Ascomicetos , Carya , Fungicidas Industriales , Carya/genética , Carya/microbiología , Transcriptoma , Árboles/genética , Ascomicetos/genética , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , FitomejoramientoRESUMEN
Genome-enabled biotechnologies have the potential to accelerate breeding efforts in long-lived perennial crop species. Despite the transformative potential of molecular tools in pecan and other outcrossing tree species, highly heterozygous genomes, significant presence-absence gene content variation, and histories of interspecific hybridization have constrained breeding efforts. To overcome these challenges, here, we present diploid genome assemblies and annotations of four outbred pecan genotypes, including a PacBio HiFi chromosome-scale assembly of both haplotypes of the 'Pawnee' cultivar. Comparative analysis and pan-genome integration reveal substantial and likely adaptive interspecific genomic introgressions, including an over-retained haplotype introgressed from bitternut hickory into pecan breeding pedigrees. Further, by leveraging our pan-genome presence-absence and functional annotation database among genomes and within the two outbred haplotypes of the 'Lakota' genome, we identify candidate genes for pest and pathogen resistance. Combined, these analyses and resources highlight significant progress towards functional and quantitative genomics in highly diverse and outbred crops.
Asunto(s)
Carya/genética , Cromosomas , Genoma de Planta , Genómica , Fitomejoramiento , Diploidia , Resistencia a la Enfermedad/genética , Variación Genética , Genotipo , Haplotipos , FenotipoRESUMEN
La Unidad de Emergencia del Area Occidente tiene una población asignada de 800.000 habitantes y es el centro de derivación de las urgencias del adulto. Estadísticas extranjeras establecen que un 2 por ciento de los fallecidos, es decir, 45 individuos por millón de habitantes por año deberían ser donantes potenciales. De acuerdo a esto, en nuestra unidad debería sser posible obtener entre 15 y 20 donantes efectivos por año. En 1992, se inició un "programa de procuramiento" a nivel local, basado en: educación y motivación; implementación básica y obtención de recursos y evaluación periódica de resultados. El objetivo de esta comunicación es presentar los resultados y motivar al personal de salud que labora en otros puntos del país para que inicien esta actividad. El número de donantes potenciales ha aumentado de 2 a 45 por año y el número de donantes efectivos de 1 a 15 por año. El número de órganos procurados ha sido de 88 riñones, y 7 hígados y se han logrado también 11 donantes de válvulas cardíacas, 10 de córneas, 2 de corazón y 1 de hueso. El número de riñones entregados al pool nacional supera al de los riñones reicibidos de otras partes. Desde 1993 se ha incrementado el número de donantes multiorgánicos. La motivación del personal médico y paramédico, el apoyo del neurólogo y el respaldo de la Dirección de la Unidad, han sido elementos importantes para lograr esta mejoría. Estos resultados demuestran que pese a las limitaciones y deficiencias existentes en los Servicios de Urgencias Públicos en Chile, es posible implementar el procuramiento de órganos, como actividad médica habitual