Genetic resistance to powdery mildew in common bean

Powdery mildew can cause severe yield losses in bean crops. Limited information about resistance sources, and nature and inheritance of resistance are available to bean breeders and plant pathologist. Sources of resistance were searched in seedling tests under controlled conditions in 44 well-known genotypes and in a Spanish germplasm core collection consisting on 201 accessions. A 0-4 scale was used to describe the infection types (IT) observed. Only six out of the 245 evaluated genotypes showed a complete resistance (IT0) without visible symptoms on the leaves: Amanda, Belneb, Cornell 49242, Negro San Luis, Porrillo Sintetico and the local accession BGE003161. Inheritance of resistance was studied in F and F segregating populations. Observed reactions in the five segregating populations fitted to Mendelian ratios with different modes of inheritance. Results revealed that cultivar Porrillo Sintetico carries two dominant and independent resistance genes: one gene conferring complete resistance (IT0), and another gene conferring IT3, characterized by a moderate mycelial development on the leaves. Both genes show a dominant epistatic relationship. Inheritance of response to powdery mildew in cv. Cornell 49242 was similar to cv. Porrillo Sintetico although the correspondence with the genes described in Porrillo Sintetico was not established. Line X2776 carries one dominant gene conferring IT3, and shares this gene with cv. Porrillo Sintetico. In cv. Amanda, two complementary genes appear to be involved in resistance to this fungus. This information will be relevant for the implementation of breeding programs focused on the development of cultivars carrying genetic resistance to powdery mildew

Quest for barley canopy architecture genes in the hortillus population and whealbi germplasm collection

Barley grains are predominantly used for animal feed and malting, and breeding traditionally focused on increase of grain yield by partitioning biomass from straw to grains. The increasing demand for renewable energy sources makes straw, and specially barley straw characterized by the largest content of carbohydrates among the cereals, a valuable product for its potential conversion into biofuels and other products. The BarPLUS project aims at finding genes, alleles and candidate lines related to barley canopy architecture and photosynthesis, to maximize barley biomass and yield (https://barplus.wordpress.com/). In this framework, our research group focuses on identifying genes and alleles controlling tillering, leaf size and leaf angle traits in barley by exploiting both induced and natural allelic variation. Using a forward genetics approach, we screened the HorTILLUS population (Szurman-Zubrzycka et al., 2018) under both field and controlled conditions, identifying 5 mutants with increased tillering and/or erect leaves. After crossing with four reference cultivars, pools of F2 wild-type and mutant plants were selected to map and identify the underlying genes by exome sequencing (Mascher et al., 2014). In parallel, TILLING of the HorTILLUS population identified four lines carrying mutations in the LBO (Lateral branching oxidoreductase) gene involved in tiller number. In order to explore also natural genetic variation, we are taking advantage of the \u2018WHEALBI\u2019 germplasm collection, which includes 403 exome sequenced diverse accessions (BustosKorts et al., 2019): a field trial on a subset of 240 lines (Fiorenzuola d\u2019Arda, Italy) allowed us to conduct a preliminary genome wide association study based on high-throughput phenotyping for leaf angle (PocketPlant3D smartphone app) and quantitative image-analysis for leaf size. Results will be compared with those from a greenhouse experiment on the same 240 accessions to analyze a wide range of morphological traits and identify associated markers and genomic regions

Genetic resistance to powdery mildew in common bean

Powdery mildew can cause severe yield losses in bean crops. Limited information about resistance sources, and nature and inheritance of resistance are available to bean breeders and plant pathologist. Sources of resistance were searched in seedling tests under controlled conditions in 44 well-known genotypes and in a Spanish germplasm core collection consisting on 201 accessions. A 0-4 scale was used to describe the infection types (IT) observed. Only six out of the 245 evaluated genotypes showed a complete resistance (IT0) without visible symptoms on the leaves: Amanda, Belneb, Cornell 49242, Negro San Luis, Porrillo Sintetico and the local accession BGE003161. Inheritance of resistance was studied in F 2 and F 2:3 segregating populations. Observed reactions in the five segregating populations fitted to Mendelian ratios with different modes of inheritance. Results revealed that cultivar Porrillo Sintetico carries two dominant and independent resistance genes: one gene conferring complete resistance (IT0), and another gene conferring IT3, characterized by a moderate mycelial development on the leaves. Both genes show a dominant epistatic relationship. Inheritance of response to powdery mildew in cv. Cornell 49242 was similar to cv. Porrillo Sintetico although the correspondence with the genes described in Porrillo Sintetico was not established. Line X2776 carries one dominant gene conferring IT3, and shares this gene with cv. Porrillo Sintetico. In cv. Amanda, two complementary genes appear to be involved in resistance to this fungus. This information will be relevant for the implementation of breeding programs focused on the development of cultivars carrying genetic resistance to powdery mildew. © 2012 Springer Science+Business Media B.V.This work was supported by grant RTA2009-093 from INIA-Ministerio de Ciencia y Tecnología, Spain. Noemí Trabanco was the recipient of a salary fellowship from Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA, Spain).Peer Reviewe

Late-stage difluoromethylation: concepts, developments and perspective

This review describes the recent advances made in difluoromethylation processes based on X–CF2H bond formation where X is C(sp), C(sp2), C(sp3), O, N or S, a field of research that has benefited from the invention of multiple difluoromethylation reagents. The last decade has witnessed an upsurge of metal-based methods that can transfer CF2H to C(sp2) sites both in stoichiometric and catalytic mode. Difluoromethylation of C(sp2)–H bond has also been accomplished through Minisci-type radical chemistry, a strategy best applied to heteroaromatics. Examples of electrophilic, nucleophilic, radical and cross-coupling methods have appeared to construct C(sp3)–CF2H bonds, but cases of stereoselective difluoromethylation are still limited. In this sub-field, an exciting departure is the precise site-selective installation of CF2H onto large biomolecules such as proteins. The formation of X–CF2H bond where X is oxygen, nitrogen or sulfur is conventionally achieved upon reaction with ClCF2H; more recently, numerous protocols have achieved X–H insertion with novel non-ozone depleting difluorocarbene reagents. All together, these advances have streamlined access to molecules of pharmaceutical relevance, and generated interest for process chemistry