Inheritance of angular leaf spot resistance in common bean line BAT 332 and identification of RAPD markers linked to the resistance gene

The existence of genetic variability for angular leaf spot (ALS) resistance in the common bean germplasm allows the development of breeding lines resistant to this disease. The BAT 332 line is an important resistance source to common bean ALS. In this work we determined the inheritance pattern and identified RAPD markers linked to a resistance gene present in BAT 332. Populations F₁, F₂,BCs and BCr derived from crosses between BAT 332 and cultivar Rudá were used. Rudá is a commercial cultivar with carioca type grains and susceptible to ALS. The resistance of BAT 332 to race 61.41 of the pathogen was confirmed. Segregation analysis of the plants indicated that a single dominant gene confers resistance. For identification of RAPD markers linked to the resistance gene, bulk segregant analysis (BSA) was used. Two RAPD markers,OPAA07₉₅₀ and OPAO12₉₅₀, linked in coupling phase at 5.10 and 5.83 cM of this gene, respectively, were identified. These molecular markers are important for common bean breeders and geneticists as source of genetic information and for marker assisted selection in breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of the anthracnose resistance gene present in Ouro Negro (Honduras 35) common bean cultivar

Ouro Negro (Honduras 35) is a highly productive Mesoamerican black seeded bean cultivar that possesses a major dominant gene conferring resistance to anthracnose (causal organism Colletotrichum lindemuthianum). In this work the anthracnose resistance gene present in Ouro Negro was characterized by studying allelic relationships to the following previously characterized anthracnose resistance genes (cultivars): Co-1 (MDRK), Co-1 ² (Kaboon), Co-1 ³ (Perry Marrow), Co-2 (Cornell 49-242), Co-3 (Mexico 222), Co-4 (TO), Co-4 ² (SEL 1308), Co-5 (SEL1360), Co-6 (AB 136), and the resistance genes present in PI 207262 and Widusa. In addition, we determined the resistance spectrum of Ouro Negro in relation to 19 pathotypes of C. lindemuthianum. The allelism tests confirmed that the dominant anthracnose resistance gene present in Ouro Negro is positioned at a locus distinct from those with which it was compared. We propose that this new gene be named Co-10. The inoculation of Ouro Negro with the 19 pathotypes of C. lindemuthianum demonstrated that Co-10 confers resistance to pathotypes 23, 64, 67, 73, 81, 83, 87, 89, 95, 102, 117, 119, 343, 453, 1033, 1545 and 1600. The identification of Co-10 is an important contribution to bean breeding programs that are in constant need of new sources of resistance to anthracnose. This revised version was published online in July 2006 with corrections to the Cover Date.     

Two microsatellite markers flanking a dominant gene for resistance to soybean cust nematode race 3

The purpose of this work was to identifymicrosatellite markers linked to a gene forresistance to Heterodera glycinesIchinohe (Soybean Cyst Nematode – SCN) insoybean cultivar Hartwig. ABC₁F₂ mapping population derivedfrom a cross between Hartwig (resistant)and the Brazilian soybean line Y23(susceptible) was used. About 200microsatellite or simple sequence repeat(SSR) primer pairs were tested in a bulkedsegregant analysis (BSA). Those thatshowed clear polymorphisms were amplifiedin the BC₁F₂ population, whichhad been previously inoculated andevaluated for resistance/susceptibility toSCN Race 3. Three SSR markers linked toSCN resistance were detected in thepopulation. Two of them, Satt 038 and Satt163, flanking a dominant resistant gene(d/a = –0.90), explained 37% of thephenotypic variance. This gene was mappedat the edge of molecular linkage group G. Broad and narrow sense heritabilities wereestimated to be 50.54% and 37.73%,respectively. A selection efficiency of91.18% was obtained with the simultaneoususe of the two markers. The identified SSRmarkers will be useful tools for assistingthe selection of homozygous genotypes andfor expediting the introgression of the SCNresistance locus from cv. Hartwig tosoybean elite cultivars.     

Multi-level characterization of perennial cotton (Gossypium hirsutum L. race marie-galante Hutch.) populations from the northeastern Brazil to the breeding and conservation of this germplasm

Genetic Resources and Crop Evolution - The remaining populations of perennial cotton (Gossypium hirsutum L. r. marie-galante Hutch.) that occur in northeastern Brazil are part of the primary gene...     

Processing of soybean products by semipurified plant and microbial alpha-galactosidases

Galactooligosaccharides (GO) are responsible for intestinal disturbances following ingestion of legume-derived products. Enzymatic reduction of GO level in these products is highly desirable to improve their acceptance. For this purpose, plant and microbial semipurified alpha-galactosidases were used for GO hydrolysis in soybean flour and soy molasses. alpha-Galactosidases from soybean germinating seeds, Aspergillus terreus, and Penicillium griseoroseum presented maximal activities at pH 4.0-5.0 and 45-65 degrees C. The KM,app values determined for raffinose by the soybean, A. terreus, and P. griseoroseum alpha-galactosidases were 3.44, 19.39, and 20.67 mM, respectively. The enzymes were completely inhibited by Ag+ and Hg2+, whereas only soybean enzyme was inhibited by galactose. A. terreus alpha-galactosidase was more thermostable than the enzymes from the other two sources. This enzyme maintained about 100% of its original activity after 3 h at 60 C. The microbial alpha-galactosidases were more efficient for reducing GO in soybean flour and soy molasses than soybean enzyme.     

Biochemical composition and indigestible oligosaccharides in Phaseolus vulgaris L. seeds

Common beans have a high nutritional value, but contain galactooligosaccharides (GO), which cause flatulence and intestinal discomfort in humans. The biochemical composition of ten bean cultivars was determined to select those of high protein and low GO contents. The cultivars varied in carbohydrate (47.02-60.17%), GO (3.12-5.71%), protein (22.17-33.50%), lipid (1.13-1.81%), moisture (11.42-12.93%) and ash contents (4.08-5.61%). 'Mexico 222' presented the highest alpha-galactosidase activity. Protein and GO contents were positively correlated. 'Perry Marrow' combined high protein and low GO concentrations, indicating it can be used in improvement programs aiming at high-quality cultivars for human consumption.     

Mapping QTLs for Witches' Broom (Crinipellis Perniciosa) Resistance in Cacao (Theobroma Cacao L.)

Molecular markers (RAPD, AFLP and microsatellites) were used to generate a linkage map and to identify QTLs associated to witches' broom (Crinipellis perniciosa) resistance in cacao (Theobroma cacao), using 82 individuals of an F₂ population derived from the clones ICS-1 (susceptible) and Scavina-6 (resistant). Fifteen evaluations of the number of brooms have been carried out in six years (1997–2002). In order to increase the precision and accuracy in the measures of resistance, each F₂ plant was cloned in three replications in a randomized block design with single-tree plots and evaluated over 2 years. Three hundred and forty-two markers were obtained, being 33 microsatellites, 77 AFLPs and 232 RAPDs. The distribution of the number of brooms in the F₂ population was skewed to resistance, suggesting the involvement of major genes controlling resistance and the repeatability estimated for resistance was 44%. A strong putative QTL was detected as being related to witches' broom resistance. Associated to this QTL, the microsatellite mTcCIR35 explained 35.5% of the phenotypic variation in resistance. This marker is being used for marker-assisted selection in Scavina-6 progenies, including those selected in private plantations, as an auxiliary tool to the phenotypic selection.     

Biochemical Composition and Indigestible Oligosaccharides in Phaseolus vulgaris L. Seeds

Common beans have a high nutritional value, but contain galactooligosaccharides (GO), which cause flatulence and intestinal discomfort in humans. The biochemical composition of ten bean cultivars was determined to select those of high protein and low GO contents. The cultivars varied in carbohydrate (47.02–60.17%), GO (3.12 – 5.71%), protein (22.17–33.50%), lipid (1.13–1.81%), moisture (11.42–12.93%) and ash contents (4.08–5.61%). ‘Mexico 222’ presented the highest α-galactosidase activity. Protein and GO contents were positively correlated. ‘Perry Marrow’ combined high protein and low GO concentrations, indicating it can be used in improvement programs aiming at high-quality cultivars for human consumption.     

DNA marker-assisted selection to pyramid rust resistance genes in “carioca” seeded common bean lines

This work reports a gene pyramiding approach assisted by DNA markers used to develop “carioca” seeded common bean (Phaseolus vulgaris L.) elite lines harboring three different rust resistance genes. Rust is among the most destructive diseases that attack P. vulgaris and cause serious damage worldwide. The rust resistance genes Ur-5 (from ‘Mexico 309’), Ur-11 (from ‘BelMiDak RR-3’), and Ur-14 (from ‘BRS Pioneiro’, a “carioca” seeded cultivar derived from the resistance source ‘Ouro Negro’) were combined in the “carioca” seeded bean cultivar ‘Rudá’. Firstly, two different backcross programs were conducted separately to produce progenies harboring individually the Ur-5 and Ur-11 genes. Molecular fingerprinting analysis was used to select plants genetically similar to ‘Rudá’ in the backcross cycles to accelerate the recurrent-background recovery. The obtained progenies were initially intercrossed and then crossed with ‘BRSMG Pioneiro’ (Ur-14). The final F₁ plants derived from these crosses were screened with DNA markers linked to the three rust resistance genes: SI19 (Ur-5), SAE19 (Ur-11) and OPX11 (Ur-14). The plants selected as harboring all the alleles of interest were used to obtain the next generations. The selection based on DNA markers was conducted up to the F_4:5 generation. We were able to select F_4:7 progenies showing all the DNA markers associated to the genes of interest and resistant to all specific races of U. appendiculatus used for phenotypically detecting each one of the rust resistance genes. Yield evaluations show that these selected lines are as productive as the recurrent parent ‘Rudá’ and high-performing control cultivars grown in Brazil.     

Genetic diversity of Phaeoisariopsis griseola in the State of Minas Gerais, Brazil

Due to the importance of common bean angular leaf spotin the state of Minas Gerais-Brazil and to the greatvariability of the pathogen, Phaeoisariopsisgriseola, monitoring races becomes an important toolfor breeding programs aiming at genetic resistance.The pathogenic variability of 30 isolates of the P. griseola, collected from various locations in thestate of Minas Gerais, was studied using the followingcommon bean differential series (Don Timóteo,Bolón Bayo, Montcalm, G 5686, Amendoin, G 11796,BAT 332, PAN 72, Cornell 49-242, México 54, Florde Mayo and G 2858). The first trifoliate leaf wasinoculated with a 2 × 10⁴ conidia/mL. Plants weremaintained at 20–22 ^°C and 95% relativehumidity for 48 hours. Symptom evaluation wasperformed 15 days after inoculation. Thirteen raceswere identified demonstrating the wide geneticvariability of the pathogen in the state of MinasGerais. Race 63.63 was the most virulent, whereas race63.23 was the most frequent (10 of 30 isolates), beingwidely distributed among the regions studied. Thevirulence phenotype indicated that the races studiedbelonged to the Mesoamerican group, which wasconfirmed when the 30 isolates were compared to Andeanand Mesoamerican standards using RAPD markers.