Generation and validation of genetic markers for the selection of carioca dry bean genotypes with the slow-darkening seed coat trait

Slow darkening (SD) is a trait that helps to maintain a brighter seed coat appearance in certain market classes of dry beans. The aim of this study was to generate new fluorescence-based markers and validate previously identified microsatellite markers for linkage to the SD trait in lines of the carioca market class. Four segregating populations were generated by Embrapa, the Brazilian Agricultural Research Corporation, from crosses between the SD cultivar BRSMG Madrepe´rola and the regular-darkening cultivars BRS Estilo, BRS Cometa, BRS Nota´vel and BRS Sublime. These populations were screened with the simple-sequence markers Pvsd- 1158 and PVM02TC116 and with a TaqManTM marker designed for the single-nucleotide polymorphism (SNP) PvbHLHp12804. A KASP marker was also designed for the PvbHLHp12804 marker for testing on advanced carioca lines developed by the University of Saskatchewan. In the carioca lines developed by Embrapa, PVM02TC116 proved unsuitable for marker-assisted selection (MAS). Both the Pvsd-1158 and PvbHLHp12804 markers were found to be tightly linked to the gene responsible for the SD trait, with genetic distances calculated at 2.8 cM for Pvsd-1158 and 2.0 and 3.1 cM for PvbbHLHp12804, respectively. These markers presented more than 97% of selection efficiency. The genotypic scoring using the PvbHLHp12804 KASP marker was perfectly correlated with the phenotype in all lines of the University of Saskatchewan. The results of this study validates the use of Pvsd-1158 as a gel-based marker for SD in carioca beans. The new fluorescence-based SNP PvbHLHp12804 markers exhibited very tight linkage to SD in carioca and pinto bean lines. These markers will be ideal for MAS for the SD trait in these market classes

Generation and validation of genetic markers for the selection of carioca dry bean genotypes with the slow-darkening seed coat trait

Slow darkening (SD) is a trait that helps to maintain a brighter seed coat appearance in certain market classes of dry beans. The aim of this study was to generate new fluorescence-based markers and validate previously identified microsatellite markers for linkage to the SD trait in lines of the carioca market class. Four segregating populations were generated by Embrapa, the Brazilian Agricultural Research Corporation, from crosses between the SD cultivar BRSMG Madrepe´rola and the regular-darkening cultivars BRS Estilo, BRS Cometa, BRS Nota´vel and BRS Sublime. These populations were screened with the simple-sequence markers Pvsd- 1158 and PVM02TC116 and with a TaqManTM marker designed for the single-nucleotide polymorphism (SNP) PvbHLHp12804. A KASP marker was also designed for the PvbHLHp12804 marker for testing on advanced carioca lines developed by the University of Saskatchewan. In the carioca lines developed by Embrapa, PVM02TC116 proved unsuitable for marker-assisted selection (MAS). Both the Pvsd-1158 and PvbHLHp12804 markers were found to be tightly linked to the gene responsible for the SD trait, with genetic distances calculated at 2.8 cM for Pvsd-1158 and 2.0 and 3.1 cM for PvbbHLHp12804, respectively. These markers presented more than 97% of selection efficiency. The genotypic scoring using the PvbHLHp12804 KASP marker was perfectly correlated with the phenotype in all lines of the University of Saskatchewan. The results of this study validates the use of Pvsd-1158 as a gel-based marker for SD in carioca beans. The new fluorescence-based SNP PvbHLHp12804 markers exhibited very tight linkage to SD in carioca and pinto bean lines. These markers will be ideal for MAS for the SD trait in these market classes

Digestible lysine for 63 to 103 day-old barrows of genetic lines selected for lean deposition

Ninety-six barrows from 63 to 103 days of age were used to evaluate the effects of dietary digestible lysine levels on performance and carcass traits of two genetic lines selected for lean deposition. Pigs with initial body weight of 23.800 ± 1.075 kg were allotted in a completely randomized block design, within a 4 × 2 factorial arrangement (four digestible lysine levels: 0.80, 0.90, 1.00, 1.10%, and two genetic lines), with six replicates and two pigs per experimental unit. There was no interaction between genetic and digestible lysine levels. The digestible lysine levels also did not influence performance or carcass traits of pigs; however, average daily lysine intake increased with increasing digestible lysine level in the experimental diets. Pigs from genetic line B had better carcass traits when compared with those from genetic line A. The level of 0.80% digestible lysine corresponding to a daily intake of 16.60 g digestible lysine meets the nutritional requirement of pigs from both genetic lines evaluated, from 63 to 103 days of age