Linkage and mapping of quantitative trait loci associated with angular leaf spot and powdery mildew resistance in common beans

Angular leaf spot (ALS) and powdery mildew (PWM) are two important fungi diseases causing significant yield losses in common beans. In this study, a new genetic linkage map was constructed using single sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), in a segregating population derived from the AND 277 x SEA 5 cross, with 105 recombinant inbred lines. Phenotypic evaluations were performed in the greenhouse to identify quantitative trait loci (QTLs) associated with resistance by means of the composite interval mapping analysis. Four QTLs were identified for ALS resistance. The QTL ALS11AS, linked on the SNP BAR 5054, mapped on chromosome Pv11, showed the greatest effect (R2 = 26.5%) on ALS phenotypic variance. For PWM resistance, two QTLs were detected, PWM2AS and PWM11AS, on Pv2 and Pv11, explaining 7% and 66% of the phenotypic variation, respectively. Both QTLs on Pv11 were mapped on the same genomic region, suggesting that it is a pleiotropic region. The present study resulted in the identification of new markers closely linked to ALS and PWM QTLs, which can be used for marker-assisted selection, fine mapping and positional cloning

Bioprospection of yeast and bacteria isolates from oral secretion of field-collected diatraea saccharalis (fabricius, 1794) (Lepidoptera: Crambidae) Antagonic to Fusarium verticillioides (Nirenberg, 1976) AND Colletotrichum falcatum (Went, 1893)

Insect symbionts may have unknown functions in the interaction between insect-plant and insect with microorganisms that co-inhabit the same space. The objective of this study was to investigate the antagonism potential of symbiont microbiota from oral secretion D. saccharalis collected in the field, against Fusarium verticillioides and Colletotrichum falcatum pathogens commonly found inside the cane. For this, 4° and 5° instar caterpillars were collected inside sugarcane varieties RB-835 054 and SP- 813 250, and brought to the lab inside the cane stalks. The microbiota of oral secretion was transferred to two selective media, NA (nutrient agar) for bacteria and DRBC (dicloran Rose Bengal Chloramphenicol) for yeast. Based on morphology and coloration of the colonies twenty colonies of bacteria and yeast were selected. Four culture media were tested in co-cultivation of F. verticillioides and C. falcatum versus bacteria or yeast isolates: PDA (potato, dextrose, agar), YEPD (yeast extract, peptone, dextrose), CCS (supplemented cane broth) and NA (Nutrient Agar). The most suitable culture medium for growth of most microorganisms was BDA. Antagonism potential of 82 bacterial isolates and 87 yeast isolates to C. falcatum and F. verticillioides was assessed using a visual scale of categories 1 to 4, with 4 being the maximum degree of antagonism. Isolates that allocated category greater than or equal to 2 were evaluated in co-culture with C. falcatum and F. verticillioides as the percentage of growth inhibition. It was possible to identify four isolates of bacteria which have the potential to inhibit growth of pathogens and 9 isolates with the same potential but with much lower percentages. These results demonstrate that some isolates of bacteria and yeast may influence the relationship between the bit-rot complex and sugarcane plant, may in future be used as a biological control of these pathogens or have some molecules of biotechnological interest extracted and purified.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Simbiontes de insetos podem ter funções desconhecidas na interação entre insetoplanta e do inseto com microrganismos que co-habitam o mesmo espaço. O objetivo desse estudo foi investigar o potencial de antagonismo da microbiota simbionte, presentes na secreção oral de Diatraea saccharalis, com os fitopatógenos Fusarium verticillioides e Colletotrichum falcatum que habitam o colmo de cana-de-açúcar. Para isso, foram coletadas, nas variedades de cana RB-835054 e SP-813250, lagartas de 4° e 5° instar e trazidas para o laboratório junto aos toletes de cana. A microbiota da secreção oral foi transferida para dois meios de cultura seletivos, NA (nutrient agar) para bactérias e DRBC (Dicloran Rosa-de-Bengala Cloranfenicol) para leveduras. Baseado na morfologia e coloração das colônias, foram selecionadas, vinte colônias de bactéria e também de levedura de 5 lagartas. Foram testados quatro meios de cultura: BDA (batata, dextrose, agar), YEPD (yeast extract, peptone, dextrose), CCS (caldo-de-cana suplementado) e NA para os testes de cultivo pareado. O meio de cultura mais adequado para o crescimento da maioria dos microrganismos foi o BDA. O potencial de antagonismo de 82 isolados de bactéria e 87 isolados de levedura a C. falcatum e F. verticillioides foi avaliado através de uma escala visual de categorias de 1 a 4, sendo 4 o grau máximo de antagonismo. Os isolados a que foi atribuída categoria maior ou igual a dois foram avaliados em co-cultivo com C. falcatum e F. verticillioides quanto à porcentagem de inibição do crescimento. Foi possível identificar 4 isolados de bactéria que tem o potencial de inibir o crescimento dos fitopatógenos e 9 isolados com o mesmo potencial, porém com porcentagens menores. Esses resultados demonstram que alguns isolados de bactérias e leveduras podem influenciar na relação existente entre o complexo broca-podridão e a planta de cana-de-açúcar, podendo, futuramente, serem utilizados como controle biológico desses fitopatógenos ou terem algumas moléculas de interesse biotecnológico extraída e purificada

Linkage and mapping of quantitative trait loci associated with angular leaf spot and powdery mildew resistance in common beans

Abstract Angular leaf spot (ALS) and powdery mildew (PWM) are two important fungi diseases causing significant yield losses in common beans. In this study, a new genetic linkage map was constructed using single sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), in a segregating population derived from the AND 277 x SEA 5 cross, with 105 recombinant inbred lines. Phenotypic evaluations were performed in the greenhouse to identify quantitative trait loci (QTLs) associated with resistance by means of the composite interval mapping analysis. Four QTLs were identified for ALS resistance. The QTL ALS11AS, linked on the SNP BAR 5054, mapped on chromosome Pv11, showed the greatest effect (R2 = 26.5%) on ALS phenotypic variance. For PWM resistance, two QTLs were detected, PWM2AS and PWM11AS, on Pv2 and Pv11, explaining 7% and 66% of the phenotypic variation, respectively. Both QTLs on Pv11 were mapped on the same genomic region, suggesting that it is a pleiotropic region. The present study resulted in the identification of new markers closely linked to ALS and PWM QTLs, which can be used for marker-assisted selection, fine mapping and positional cloning