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

Abstract

Resumo -O objetivo deste estudo foi a caracterização fenotípica e molecular de 31 genótipos de feijão do tipo carioca, quanto à resistência aos patógenos da antracnose, ferrugem e mancha-angular. Foram realizadas inoculações com 13 patótipos de Colletotrichum lindemuthianum, dois de Uromyces appendiculatus e sete de Pseudocercospora griseola. Na caracterização molecular, foram utilizados cinco marcadores moleculares previamente identificados, ligados a diferentes alelos de resistência aos patógenos. Sete genótipos apresentaram resistência a 12 patótipos de C. lindemuthianum. Nove genótipos apresentaram resistência a cinco patótipos de P. griseola. Dez genótipos foram resistentes aos patótipos de U. appendiculatus. As linhagens VC 2, VC 3 e VC 5, além da Rudá-R (linhagem piramidada com cinco genes que conferem resistência a alguns patótipos de antracnose, ferrugem e mancha-angular), foram as que se destacaram quanto à resistência múltipla aos patógenos acima citados. Foi detectado polimorfismo molecular entre a maioria dos genótipos com a Rudá-R, o que indica a possibilidade de uso dos marcadores moleculares SCARF10, SCARY20, SCARAZ20, SCARH13 e OPX11.Termos para indexação: Colletotrichum lindemuthianum, Phaseolus vulgaris, Pseudocercospora griseola, Uromyces appendiculatus, marcador molecular, melhoramento do feijoeiro. Phenotypic and molecular characterization of genitors of carioca-type common bean regarding their resistance to pathogensAbstract -The present study aimed at the phenotypic and molecular characterization of 31 genotypes of the carioca-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, identified in advance, and linked to the different alleles of pathogens' resistance, were used. Seven genotypes showed resistance 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 and VC 5, besides Rudá-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. Molecular polymorphism was detected between the most genotypes with Rudá-R, which indicates the possibility of using the molecular markers SCARF10, SCARY20, SCARAZ20, SCARH13 and OPX11 .

Introgression of resistance to pathogens in common bean lines with the aid of molecular markers

“…Sanglard et al (2007) and Melo et al (2008) also obtained this same result with the Rudá-R line. Molecular characterization of the recurrent parents shows the possibility of monitoring of most of the resistance alleles in the populations under selection, with the exception of lines BRSMG Talismã and VC9.…”

“…The former was not polymorphic for the marker SCARH13, since it also showed amplification for this marker. This result contradicts the result found by Melo et al (2008) in which this cultivar did not show the band in question and corroborates the result of Sanglard et al (2007). The VC9 line showed amplification in reference to the primer SCARY20, which marks the allele Co-4 and, therefore, does not allow the monitoring of this allele in the population arising from this parent.…”

“…However, this result is a false positive, considering that this line showed susceptibility to race 65 (Table 1) and therefore does not have the Co-4 allele. It is known that this line has the Co-10 allele arising from the cultivar Ouro Negro (Melo et al 2008). This fact is confirmed by the phenotypic characterization in which VC9 proved to be resistant to race 453 of C. lindemuthianum since this dominant allele confers vertical resistance to this race (Table 1).…”

Common bean breeding for resistance to anthracnose and angular leaf spot assisted by SCAR molecular markers

“…These results suggest that these families carried the alleles Co-4 and Co-10 and/or the allele Co-6, considering that the source of resistance used in the crosses (Rudá-R) carries these three alleles (Table 5). It is important to emphasize that race 65 of C. lindemuthianum has been reported as one of the most frequent in the common bean producing regions of Brazil (Carbonell et al 1999, Talamini et al 2004 and that the cultivars Pérola and Rudá are susceptible to this race (Melo et al 2008).…”

“…For the cariocatype common bean, the preference has been for grains with opaque tegument, cream color with light brown stripes and light underground. The cultivar Pérola, for example, the standard for grain type and yield, is the most cultivated in Brazil, even though it is susceptible to the main races of C. lindemuthianum and P. griseola that predominate in the producing regions in Brazil (Faleiro et al 2001, Melo et al 2008.…”