Everaldo Gonçalves de Barros

Genetic characterization of anthracnose resistance genes Co-4 3 and Co-9 in common bean cultivar tlalnepantla 64 (PI 207262)

Tlalnepantla 64 (PI 207262) is an important source of genes for resistance to common bean anthracnose, caused by Colletotrichum lindemuthianum. However, these genes have not been fully characterized. Inheritance studies using crosses involving PI 207262 show that two independent genes confer resistance to anthracnose. Allelism tests showed that the genes are located at distinct loci from the previously identified resistance genes Co-1, Co-2, Co-3, Co-5, Co-6, and Co-10. Also, no segregation was observed in relation to Co-4, Co-42, Co-9, and to the gene present in cultivar Widusa, indicating that PI 207262 harbors alleles of these genes. We conclude that PI 207262 harbors two anthracnose resistance genes, Co-4 and Co-9. The Co-4 allele of PI 207262 would be different from Co-4 and Co-42 and it is proposed Co-43 as the genetic symbol for this resistance allele. As PI 207262 is the parent of BAT 93, the Co-9 symbol represents the gene of both cultivars. Also, one allele of Co-9 gene was detected in cultivar Widusa.

Propriedades físico-químicas de polifenoloxidase de feijão (Phaseolus vulgaris L.)

The polyphenoloxidase activity of nine bean (Phaseolus vulgaris L.) cultivars (Arua, Apore, A774, Carioca, Diamante Negro, Ouro Branco, Perola, RAO 33 e Ruda) were studied. The crude enzyme extract of the nine cultivars was found to have optimum pH in 7.2 using catechol as substrate. No PPO activity in beans (Phaseolus vulgaris L.) was observed using D,L DOPA and gallic acid as substrate.

Padrão de herança e critérios de seleção para resistência às raças 3 e 9 do nematóide-de-cisto-da-soja

The objective of this work was to determine soybean resistance inheritance to Heterodera glycines Ichinohe (soybean cyst nematode - SCN) races 3 and 9, as well as to evaluate the efficiency of direct and indirect selection in a soybean population of 112 recombinant inbred lines (RIL) derived from the resistant cultivar Hartwig. The experiment was conducted in a completely randomized design, in Londrina, PR, Brazil. The estimated narrow-sense heritabilities for resistance to races 3 and 9 were 80.67 and 77.97%. The genetic correlation coefficient (rg = 0.17; p<0.01) shows that some genetic components of resistance to these two races are inherited together. The greatest genetic gain by indirect selection was obtained to race 9, selecting to race 3 due to simpler inheritance of resistance to race 9 and not because these two races share common resistance genes. The resistance of cultivar Hartwig to races 3 and 9 is determined by 4 and 2 genes, respectively. One of these genes confers resistance to both races, explaining a fraction of the significant genetic correlation found between resistance to these SCN races. The inheritance pattern described indicates that selection for resistance to SCN must be performed for each race individually.

Comparação de blocos casualizados e testemunhas intercalares na estimação de parâmetros genéticos em feijoeiro (1)

The main goal of this work was to compare two experimental designs to estimate different genetic parameters based on the evaluation of 154 recombinant inbred lines (RIL) of the common bean (Phaseolus vulgaris L.). Random blocks (RB) and another design, in which, each line was represented by only one plot and compared with intercalated checks (IC) were the designs used. Lines at the F7 generation were obtained by the single seed descent method from a cross between Ouro Negro and Ruda cultivars used as checks in the IC design. Eight quantitative characteristics were evaluated and seven genetic parameters were estimated for each characteristic. The mean values for the characteristics and the experimental precision in both designs were similar. The RB design was better suited to detect genetic variability and was also more accurate than the IC design. Coincidence coefficients between the lines selected in both experimental designs were between 32% and 78% and the smallest values were obtained for traits with low heritabilities.

Caracterização fenotípica e molecular de genitores de feijão tipo carioca quanto à resistência a patógenos

Abstract€–€The present study aimed at the phenotypic and molecular characterization of 31€genotypes of thecarioca-type common bean regarding the resistance to anthracnose, rust and angular leaf spot (ALS) pathogens.Thirteen pathotypes of Colletotrichum lindemuthianum , two of Uromyces appendiculatus and seven of Pseudocercospora griseola were inoculated. In the molecular characterization, five molecular markers, identifiedin advance, and linked to the different alleles of pathogens’ resistance, were used. Seven genotypes showedresistance to 12€pathotypes of C.€lindemuthianum . Nine genotypes presented resistance to five pathotypes of P.€griseola . Ten genotypes were resistant to the pathotypes of U.€appendiculatus . The lines VC€2, VC€3 andVC€5, besides Ruda-R (line pyramided with five genes which confer resistance to some pathotypes of anthracnose,rust and ALS), were the stood out for multiple resistance to the pathogens above described. Molecularpolymorphism was detected between the most genotypes with Ruda-R, which indicates the possibility of usingthe molecular markers SCARF10, SCAR Y20, SCARAZ20, SCARH13 and OPX1 1 .Index terms:

Enzimas marcadoras de indução de resistência diferencialmente reguladas em soja resistente e suscetível à ferrugem‑asiática‑da‑soja

The objective of this work was to evaluate induced resistance to Asian soybean rust by means of enzyme activities in soybean genotypes contrasting as to their susceptibility to Phakopsora pachyrhizi. Total protein and the activities of five induced resistance marker enzymes (lipoxygenases, peroxidases, phenylalanine ammonia-lyase, chitinases and β-1, 3-glucanases) were evaluated in leaf extracts of soybean plants of the genotypes Embrapa 48 (susceptible) and PI 561356 (resistant), inoculated or not with the pathogen. Discrepant defense responses were obtained between the two genotypes and among the leaf harvest times (12, 72, and 168 hours after inoculation). The induction response of these enzymes resembles the biphasic defense in Embrapa 48 and is consistent with that observed in other pathological systems. However, the genotype PI 561356 responded with a decrease in total protein concentration and in enzymatic activities, indicating a general reduction in the metabolism of the infected plants. There is an important mechanism of resistance for the genotype PI 561356, not yet reported, which is grounded on the metabolic ways involving these induced resistance marker enzymes and on the mechanisms that use lower concentrations of total protein, such as the ones with metabolic pathways in response cascade.