White Mold (WM) is a yield–limiting disease found in soybean. However, up to now no cultivars have been genetically resistant to this disease. Given this context, the present study aimed to develop ...superior soybean lines with resistance to WM, while maintaining other desirable agronomic traits. Two early maturing soybean cultivars (i.e., EMGOPA 316 and MG/BR 46–Conquista), moderately resistant to WM were used for biparental crosses from which the analyzed population was derived. Therefore, we assessed the resistance to WM in early generation testing of this population. Additionally, we determined the agronomic traits, genetic parameters and selection gains. From 348 F2 genotypes, 35 transgressive genotypes moderately resistant to WM were identified, amongst which 22 genotypes showed desirable agronomic traits for early cycle and grain yield. Moreover, 69 lines were selected as the most promising genotypes for each agronomic trait (i.e. based on the number of days to flowering and maturity, plant height at flowering and maturity, number of nodes on main stem at flowering and maturity, number of pods, grain yield, etc.). Among these selected lines, ten progenies emerged as the superior genotypes for grain yield and early cycle. All together, these results demonstrated that the cross between EMGOPA 316 × MG/BR 46 (Conquista) revealed promising progenies with moderate resistance to WM and/or desirable agronomic traits. Thus, these lines could be used as future resources for breeding efforts aimed at improving resistance to WM.
Asian soybean rust (ASR), caused by the phytopathogen Phakopsora pachyrhizi Sydow & Sydow, is a worldwide distributed fungal disease responsible for causing damages in soybean crops Glycine max (L.) ...Merril of up to 90% of its productive potential. So far, due to limited availability of resistant varieties, fungicide application is the most widely used strategy for ASR control, although some populations of the pathogen have shown reduced sensitivity to certain active ingredients. Several methods have been described to measure the sensitivity of a fungus to a given fungicide, or even the fungitotoxicity of a chemical. The most used tests are spore germination in water-agar medium and disease severity in detached soybean leaflets. Two experiments were carried out with populations of the pathogen from Uberlândia - MG and from Chapadão do Sul - MS. The results showed the reduction of benzovindiflupyr efficiency in relation to spore germination and disease severity for the MS population. The novel carboxamide Sumitomo Chemical (S2399T) was highly efficient for both populations inhibiting the pathogen at 0.1 ppm. The carboxamide fluxapiroxade (EC50 = 1-10 ppm) was stable in the two commercial products (Orkestra - Fluxapiroxade and Ativum - Epoxiconazole). Multisite fungicides (chlorothalonil and mancozeb) at concentrations above 100 ppm may be used in the management of resistance in the fields of Brazil associated with strobilurins, triazoles, and carboxamides. The efficiency of the main active ingredient tested depends on the formulation and others fungicides used in the commercial fungicide.
The Xanthomonadaceae family consists of species of non-pathogenic and pathogenic γ-proteobacteria that infect different hosts, including humans and plants. In this study, we performed a comparative ...analysis using 69 fully sequenced genomes belonging to this family, with a focus on identifying proteins enriched in phytopathogens that could explain the lifestyle and the ability to infect plants. Using a computational approach, we identified seven phytopathogen-enriched protein families putatively secreted by type II secretory system: PheA (CM-sec), LipA/LesA, VirK, and four families involved in N-glycan degradation, NixE, NixF, NixL, and FucA1. In silico and phylogenetic analyses of these protein families revealed they all have orthologs in other phytopathogenic or symbiotic bacteria, and are involved in the modulation and evasion of the immune system. As a proof of concept, we performed a biochemical characterization of LipA from Xac306 and verified that the mutant strain lost most of its lipase and esterase activities and displayed reduced virulence in citrus. Since this study includes closely related organisms with distinct lifestyles and highlights proteins directly related to adaptation inside plant tissues, novel approaches might use these proteins as biotechnological targets for disease control, and contribute to our understanding of the coevolution of plant-associated bacteria.
Asian soybean rust (ASR), caused by the phytopathogen Phakopsora pachyrhizi Sydow & Sydow, is a worldwide distributed fungal disease responsible for causing damages in soybean crops Glycine max (L.) ...Merril of up to 90% of its productive potential. So far, due to limited availability of resistant varieties, fungicide application is the most widely used strategy for ASR control, although some populations of the pathogen have shown reduced sensitivity to certain active ingredients. Several methods have been described to measure the sensitivity of a fungus to a given fungicide, or even the fungitotoxicity of a chemical. The most used tests are spore germination in water-agar medium and disease severity in detached soybean leaflets. Two experiments were carried out with populations of the pathogen from Uberlândia - MG and from Chapadão do Sul - MS. The results showed the reduction of benzovindiflupyr efficiency in relation to spore germination and disease severity for the MS population. The novel carboxamide Sumitomo Chemical (S2399T) was highly efficient for both populations inhibiting the pathogen at 0.1 ppm. The carboxamide fluxapiroxade (EC50 = 1-10 ppm) was stable in the two commercial products (Orkestra - Fluxapiroxade and Ativum - Epoxiconazole). Multisite fungicides (chlorothalonil and mancozeb) at concentrations above 100 ppm may be used in the management of resistance in the fields of Brazil associated with strobilurins, triazoles, and carboxamides. The efficiency of the main active ingredient tested depends on the formulation and others fungicides used in the commercial fungicide.
PDF
