Abstract:This study was realized with the objective of verifying the resistance to white mold of common bean progenies derived from recurrent selection for resistance to angular leaf spot. The plant material used was obtained from a program of recurrent selection
“…Recent studies concerning white mold resistance have been conducted in Brazil to identify sources of resistance (Carvalho et al, 2013;Souza et al, 2014;Lehner et al, 2015b) or understand the genetic control of resistance (Antonio et al, 2008;Carneiro et al, 2011). In a previous study (Lehner et al, 2015b), the physiological resistance of 20 putative sources of white mold resistance from the Bean White Mold Nursery (University of Nebraska, USA) was assessed.…”
White mold caused by the fungus Sclerotinia sclerotiorum is the most yield-limiting disease of common bean in Brazil. To date, there has been no commercial cultivar resistant to this disease. In a greenhouse we evaluated white mold resistance sources (Cornell 605, A195 and G122) against eight isolates of S. sclerotiorum from five Brazilian states. A Brazilian cultivar (BRSMG Madrepérola) and a susceptible check (Beryl) were used as control. Treatments were arranged in factorial combinations (5 × 8) in a completely random design with four replicates.Disease severity was assessed on a rating scale of 1-to-9 together with lesion length, which was used to determine an area under the disease progress curve (AUDPC). Polymorphisms detected in ten microsatellite loci were used to assess variability between the isolates. Each isolate was a distinct haplotype; they formed a genetic tree with two clusters. One cluster was formed by three isolates collected from the states of Minas Gerais and São Paulo (southeastern); the others, by isolates from Paraná, Santa Catarina (southern), Goiás (Mid-western), and again, Minas Gerais.Genotype × isolate interaction was significant. In general, Beryl was more susceptible than BRSMG Madrepérola. Considering the AUDPC and/or the white mold reaction score, Cornell 605 exhibited more physiological resistance than BRSMG Madrepérola to seven isolates, A195 to five isolates, and G122 to two isolates. Our results suggest that Cornell 605 is the best source of resistance to white mold for the southern region, whereas Cornell 605 and A195 are somewhat superior to G122 for the southeastern and mid-western regions.
“…Recent studies concerning white mold resistance have been conducted in Brazil to identify sources of resistance (Carvalho et al, 2013;Souza et al, 2014;Lehner et al, 2015b) or understand the genetic control of resistance (Antonio et al, 2008;Carneiro et al, 2011). In a previous study (Lehner et al, 2015b), the physiological resistance of 20 putative sources of white mold resistance from the Bean White Mold Nursery (University of Nebraska, USA) was assessed.…”
White mold caused by the fungus Sclerotinia sclerotiorum is the most yield-limiting disease of common bean in Brazil. To date, there has been no commercial cultivar resistant to this disease. In a greenhouse we evaluated white mold resistance sources (Cornell 605, A195 and G122) against eight isolates of S. sclerotiorum from five Brazilian states. A Brazilian cultivar (BRSMG Madrepérola) and a susceptible check (Beryl) were used as control. Treatments were arranged in factorial combinations (5 × 8) in a completely random design with four replicates.Disease severity was assessed on a rating scale of 1-to-9 together with lesion length, which was used to determine an area under the disease progress curve (AUDPC). Polymorphisms detected in ten microsatellite loci were used to assess variability between the isolates. Each isolate was a distinct haplotype; they formed a genetic tree with two clusters. One cluster was formed by three isolates collected from the states of Minas Gerais and São Paulo (southeastern); the others, by isolates from Paraná, Santa Catarina (southern), Goiás (Mid-western), and again, Minas Gerais.Genotype × isolate interaction was significant. In general, Beryl was more susceptible than BRSMG Madrepérola. Considering the AUDPC and/or the white mold reaction score, Cornell 605 exhibited more physiological resistance than BRSMG Madrepérola to seven isolates, A195 to five isolates, and G122 to two isolates. Our results suggest that Cornell 605 is the best source of resistance to white mold for the southern region, whereas Cornell 605 and A195 are somewhat superior to G122 for the southeastern and mid-western regions.
“…Both the genotypes most resistant to oxalic acid (POTÊNCIA, 2010L011, P98Y30 and P98Y12) and those with higher means, that is, most sensitive to oxalic acid (P98Y51, M7639RR, M7908RR and 2010L021), expressed reactions consistent with resistance evaluated in the field. As such, in addition to the advantage of not using the etiological agent and therefore eliminating pathogen aggressiveness variability (Kull et al, 2004), this method is also not associated with the climactic effects that interfere in disease incidence and progression (Souza et al, 2014). Thus, these results confirm the potential for oxalic acid use in plant breeding programs, initially as a mass selection method to identify white mold-resistance genotypes.…”
White mold, caused by the fungus Sclerotinia sclerotiorum, is considered the second most destructive disease affecting soybean crops. The pathogen is controlled by integrating different methods, including genetic resistance. However, genotype selection techniques often lack the desired efficiency. As such, the aim of this study was to use sensitivity to oxalic acid as a selection method for white mold-resistant soybean genotypes and compare the results against soybean S. sclerotiorum infection in two agroecosystems, namely Barreiras (Bahia state-BA) and Jataí (Goiás state-GO). Eleven genotypes were planted and evaluated in the Barreiras region and 10 in Jataí, three of which were common to both areas. Assessments in the field involved analyzing white mold incidence, growth cycle and yield. For the oxalic acid-based selection method, the soybean genotypes were exposed to a 20 mM oxalic acid solution and wilting was assessed. In oxalic acid sensitivity testing, both the resistant and susceptible genotypes mirrored the resistance expressed under field conditions. Thus, oxalic acid sensitivity testing was considered suitable for use in breeding programs aimed at selecting white mold-resistant genotypes.
“…In other studies, significant differences were also reported between populations improved in selection cycles, compared to the parents and progenies for the traits: hypocotyl diameter, plant architecture, grain yield and white mold susceptibility in common bean. (Souza et al 2014;Anjos et al 2018). Once the genetic divergence between treatments is known, genetic components can be estimated.…”
Section: Resultsmentioning
confidence: 99%
“…For the above-ground plant parts of common bean, numerous recurrent selection studies have already addressed variables such as crop cycle, growth habit, grain yield, grain appearance, disease resistance and others (Ramalho et al 2005;Silva et al 2010;Silva et al 2013;Souza et al 2014;Alves et al 2015;Leite et al 2016;Pereira et al 2016;Anjos et al 2018). The scarcity of studies focused on the root system might be related to the difficulty of phenotyping this trait in a large number of progenies.…”
Genetic variability is essential for gains in breeding programs. The cyclic process of progeny recombination is a strategy to raise the chances of selecting better genotype combinations. The objective of this study was to identify superior progenies between common bean genes groups in first recurrent selection cycle for root system traits. Parents of the Andean and Middle American gene groups were hybridized in a complete diallel scheme. Thereafter, the parents and F 1 and F 2 populations were planted in the field. To establish the base population of recurrent selection (C 0 ), seven segregating populations (F 2 ) with superior performance for root system were selected and intercrossed, resulting in recombinant progenies (C 1 ). To estimate the selection gain, the parents and C 0 and C 1 genotypes were compared with regard to the following variables: total root length (TRL, cm), projected root area (PRA, cm²), root volume (VOL, cm³) and number of root tips (RT). The difference between genotype combinations indicates the presence of genetic variability and effectiveness of recurrent selection. The mean genetic progress for root system-related traits was 12.9% (TRL), 12.6% (PRA), 12% (VOL) and 11.5% (RT) in the first recombination cycle. The mean phenotypic performance of seven of the C 1 progenies exceeded that of their parents for all root system traits. These progenies are promising as base populations of the next selection cycle.
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