RESUMO
KEY MESSAGE: Linkage and genome-wide association analyses using high-throughput SNP genotyping revealed different loci controlling resistance to different isolates of race 65 of Colletotrichum lindemuthianum in common bean. Development of varieties with durable resistance to anthracnose is a major challenge in common bean breeding programs because of the extensive virulence diversity of Colletotrichum lindemuthianum fungus. We used linkage and genome-wide association analyses to tap the genomic regions associated with resistance to different isolates of race 65. Linkage mapping was done using an F2 population derived from the cross between the Mesoamerican common beans BRS Estilo x Ouro Vermelho, inoculated with two different isolates of race 65. Association genetics relied on a diversity common bean panel containing 189 common bean accessions inoculated with five different isolates of race 65 as an attempt to validate the linkage analysis findings and, eventually, identify other genomic regions associated with resistance to race 65. The F2 population and diversity panel were genotyped with the BARCBean6K_3 Illumina BeadChip containing 5398 SNP markers. Both linkage and genome-wide association analyses identified different loci controlling resistance to different isolates of race 65 on linkage group Pv04. Genome-wide association analysis also detected loci on Pv05, Pv10 and Pv11 associated with resistance to race 65. These findings indicate that resistance to race 65 can be overcome by the virulence diversity among different isolates of the same race and could lead to the loss of resistance after cultivar release. We identified 25 resistant common bean cultivars to all five isolates of race 65 in the diversity panel. The accessions should be useful to develop cultivars combining different resistance genes that favor durable resistance to anthracnose in common bean.
Assuntos
Cromossomos de Plantas/genética , Colletotrichum/isolamento & purificação , Resistência à Doença/genética , Phaseolus/genética , Doenças das Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas , Mapeamento Cromossômico , Colletotrichum/patogenicidade , Resistência à Doença/imunologia , Regulação da Expressão Gênica de Plantas , Phaseolus/microbiologia , Melhoramento Vegetal , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Polimorfismo de Nucleotídeo ÚnicoRESUMO
The race 65 of Colletotrichum lindemuthianum, etiologic agent of anthracnose in common bean, is distributed worldwide, having great importance in breeding programs for anthracnose resistance. Several resistance alleles have been identified promoting resistance to this race. However, the variability that has been detected within race has made it difficult to obtain cultivars with durable resistance, because cultivars may have different reactions to each strain of race 65. Thus, this work aimed at studying the resistance inheritance of common bean lines to different strains of C. lindemuthianum, race 65. We used six C. lindemuthianum strains previously characterized as belonging to the race 65 through the international set of differential cultivars of anthracnose and nine commercial cultivars, adapted to the Brazilian growing conditions and with potential ability to discriminate the variability within this race. To obtain information on the resistance inheritance related to nine commercial cultivars to six strains of race 65, these cultivars were crossed two by two in all possible combinations, resulting in 36 hybrids. Segregation in the F2 generations revealed that the resistance to each strain is conditioned by two independent genes with the same function, suggesting that they are duplicated genes, where the dominant allele promotes resistance. These results indicate that the specificity between host resistance genes and pathogen avirulence genes is not limited to races, it also occurs within strains of the same race. Further research may be carried out in order to establish if the alleles identified in these cultivars are different from those described in the literature.
Assuntos
Duplicação Gênica , Genes de Plantas , Phaseolus/microbiologia , Colletotrichum , Phaseolus/genéticaRESUMO
Background and Aims. Food allergy (FA) is a common disease that is rapidly increasing in prevalence for reasons that remain unknown. Objective. The aim of this study was to analyze the clinical characteristics and anthropometric data of patients with food allergies followed in a tertiary centre of allergy and immunology. Methods. A retrospective study was performed that assessed the data records of patients with food allergy diagnosis, covering a period from February 2009 to February 2012. Results. 354 patients were evaluated in the period; 228 (69.1%) patients had a confirmed FA diagnosis. The z-scores for weight-for-age, height-for-age, and body mass indices-for-age showed lower significant values in the FA group compared with the non-FA group by Mann-Whitney test, with significance values of P = 0.0005, P = 0.0030, and P = 0.0066, respectively. There were no statistical differences in sex, gestational age, birth type, breastfeeding period, and age of introduction of complementary formulas based on cow milk protein between groups. Conclusion. FA patients had a lower growth rate in comparison with patients without FA. The early recognition of food allergies with the establishment of protein-implicated diet exclusion, in association with an adequate nutrient replenishment, is important to reduce the nutritional impact of food allergies.