ABSTRACT: Common bean is a worldwide important crop. The development of varieties with durable resistance to diseases is a major challenge in common bean breeding. The present study aimed at evaluating the phenotypic and molecular selection of anthracnose resistance in a population obtained by assisted backcrossing from IAC Formoso (resistant, donor parent) × BRS Pérola (susceptible, recurrent parent). Nine microsatellites (SSRs) and one Sequence Tagged Sites (STS) markers previously linked to ANT resistance were used to genotype this progeny, and the results showed that the selection of the genotypes closest to the donor parent in the BC1F1 population decreased the number of backcrossing cycles necessary to obtain advanced isogenic lines, potentiating the use of this tool for early selection of resistant cultivars. A total of 31 % of the BC1F1 progeny was selected and backcrossed again. The progeny derived from the second backcross (BC2F3) was selected for the Carioca grain ideotype, and 42 % of the genotypes showed high resistance to anthracnose under controlled conditions of infection for races 65 and 81. Superior resistant plants were selected and evaluated under natural conditions of infection to fusarium wilt and angular leaf spot, allowing the selection of two inbred lines with higher resistance to anthracnose, fusarium wilt, angular leaf spot and postharvest quality traits such as yield, 100 seed weight, L value at seed harvest grain darkening and cooking time. The approach outlined in this paper proved to be effective to simultaneously select for disease resistance without losing technological quality aspects of the bean.

Abstract Common bacterial blight (CBB) is an important disease in Phaseolus vulgaris L. A carioca diversity panel (CDP) composed of 149 cultivars of common bean was genotyped with 1,616 SNPs and evaluated for Xanthomonas phaseoli pv. phaseoli (Xap) resistance aiming to identify QTLs. Phenotypic evaluation was done in controlled conditions. The plants displayed in a randomized block design, with 3 replications were evaluated ten days after inoculation. GWAS analysis using the BLINK model identified one SNP on chromosome Pv07, with a different genomic location in relation to previous studies. Considering a confidence interval of 100 kb, gene annotation identified 13 candidate genes related to defense-associated genes, and their key functional motives were discussed. The marker identified may constitute an important resource for future marker assisted CBB resistance breeding.

Abstract IAC Nuance and IAC Tigre are special common bean cultivars for consumption in Brazil and for international markets. IAC Nuance has a 75-day cycle, with cranberry type rajado (streaked/dappled) bean seeds. IAC Tigre has 85-day cycle, a cream-colored seed coat with brown specks (pinto bean type). These cultivars are moderately resistant to anthracnose, angular leaf spot, fusarium wilt, common bacterial blight, and bacterial wilt.

Abstract IAC 1849 Polaco is a common bean cultivar with a carioca (beige/cream-colored with brown stripes) seed coat, 75-day mean maturity , semi-upright plant architecture, tolerance to seed darkening, mean 1000-seed weight of 240 grams, resistance to the main diseases in common bean, and mean seed yield of 2464 kg ha-1 obtained in 18 experiments.

Abstract IAC Netuno, a black common bean cultivar with high grain yield potential, 2968.20 kg ha-¹, upright plant architecture and Type II indeterminate growth habit, about a 90-day cycle, and 1000-seed weight of 230 grams, recommended for all common bean crop seasons in the state of São Paulo.

Abstract IAC 1850 is a common bean cultivar with a carioca (beige-colored with brown stripes) seed coat, average cycle of 88 days, semi-upright plant architecture, tolerance to seed coat darkening, 1000 seed weight of 280 grams, resistance to the main diseases in common bean, and a high average yield (2,857 kg ha-1) obtained in 36 experiments conducted in different regions in Brazil.

Abstract IAC Sintonia, new common bean cultivar, was developed to incorporate moderate resistance to the main pathogens Fusarium oxysporum and Colletotrichum lindemuthianum allied to great grain yield observed, 5,750.00 kg ha-1. IAC Sintonia has semi-upright architecture and indeterminate growth habit (Type II), cycle is around 90 days and, 1000 seed weight of 280 grams.

Abstract The common bean is characterized by high sensitivity to drought and low productivity. Breeding for drought resistance in this species involves genes of different genetic groups. In this work, we used a SEA 5 x AND 277 cross to map quantitative trait loci associated with drought tolerance in order to assess the factors that determine the magnitude of drought response in common beans. A total of 438 polymorphic markers were used to genotype the F8 mapping population. Phenotyping was done in two greenhouses, one used to simulate drought and the other to simulate irrigated conditions. Fourteen traits associated with drought tolerance were measured to identify the quantitative trait loci (QTLs). The map was constructed with 331 markers that covered all 11 chromosomes and had a total length of 1515 cM. Twenty-two QTLs were discovered for chlorophyll, leaf and stem fresh biomass, leaf biomass dry weight, leaf temperature, number of pods per plant, number of seeds per plant, seed weight, days to flowering, dry pod weight and total yield under well-watered and drought (stress) conditions. All the QTLs detected under drought conditions showed positive effects of the SEA 5 allele. This study provides a better understanding of the genetic inheritance of drought tolerance in common bean.

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.

Because of the continuous introduction of germplasm from abroad, some collections have a high number of accessions, making it difficult to explore the genetic variability present in a germplasm bank for conservation and breeding purposes. Therefore, the aim of this study was to quantify and analyze the structure of genetic variability among 500 common bean accessions to construct a core collection. A total of 58 SSRs were used for this purpose. The polymorphism information content (PIC) in the 180 common bean accessions selected to compose the core collection ranged from 0.17 to 0.86, and the discriminatory power (DP) ranged from 0.21 to 0.90. The 500 accessions were clustered into 15 distinct groups and the 180 accessions into four distinct groups in the Structure analysis. According to analysis of molecular variance, the most divergent accessions comprised 97.2% of the observed genetic variability present within the base collection, confirming the efficiency of the selection criterion. The 180 selected accessions will be used for association mapping in future studies and could be potentially used by breeders to direct new crosses and generate elite cultivars that meet current and future global market needs.