Melhoramento genético do feijoeiro com ênfase na piramidação de genes de resistência à mancha-angular

• Autor(a) principal: Sanglard, Demerson Arruda
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4782
• topic: Piramidação; Marcadores moleculares; Phaeoisariopsis griseola; Pyramiding; Molecular markers; Phaeoisariopsis griseola; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA MOLECULAR E DE MICROORGANISMOS

"Pyramiding is a strategy for the achievement of cultivars resistant to a larger number of pathotypes for a longer period of time and its objective is to incorporate in one single cultivar the largest possible number of resistance genes. In order to transfer rust resistance genes (Ur-ON), anthracnose (Co-10), and angular leaf spot (Phg-ON), from the cultivar Ouro Negro to the cultivar Pérola, and the angular leaf spot resistance gene (Phg-3) from the cultivar Cornell 49-242 to the cultivar Rudá, two backcrossing subprograms were conducted. To achieve this goal, inoculations with the pathogens which incite the diseases, analyses of molecular fingerprinting, molecular markers linked to the resistant genes and progeny tests were used. By means of the backcrossing method, four families were achieved BC3F5 (Pérola x Ouro Negro) homozygotes for the three diseases, which have simultaneously the bands with specific sizes linked to the resitance loci: OPX11550a, OPAJ18560a, SCAR F101050a and SCAR BA08560a (Ur-ON and Co-10); SCAR BA16669a and SCAR AA19650a (Phg-ON). It was also possible to achieve the plants BC2F1 (Rudá x Cornell 49-242) resistant to the angular leaf spot and bearing the molecular mark produced by the amplification of SCAR N02890a linked to the gene Phg-3. Those plants were crossed with a line called Rudá R , which already has five resistant genes pyramided, one for the rust (Ur-ON), other for the angular leaf spot (Phg-1) and three others for the anthracnose (Co-4, Co-10 e Co-6). According to studies on allelism previously carried out and the available lines, the possible and best combinations were stablished aiming the pyramiding of resistance genes to the angular leaf spot. In a first phase, the crossings were carried out in a directed form in two schemes separatedly conducted: lines MAR-138A-1-11-4 x BAT-67-15-8 and MEX-37-3-6-3 x Rudá R . Considering the first crossing scheme, it was used the pathotype 63.19 of Phaeoisariopsis griseola for verifying the hybrid nature of the plants F1. The resistant plants had their DNA extracted and amplified with the molecular markers OPE04500a and OPAO12950a. The resistant plants F1 which presented molecular marks were intercrossed with the line Rudá R . This way, plants F1 (triple hybrid) were achieved, which were inoculated with the pathotype 65 of Colletotrichum lindemuthianum and monitored with the molecular markers: SCAR F101050a (Ur-ON and Co-10), SCAR BA8560a (Ur-ON and Co-10), SCAR AZ20845a (Co-4), SCAR Y20830a (Co-6), SCAR H13520a (Phg-1), OPE04500a (Phg-4 e/ou Phg-52) and OPAO12950a (Phg-62). The generation F2 segregated for all these loci, but plants bearing all the marks were found. In the second crossing scheme, plants F1 MEX-37-3-6-3 x Rudá R were improved by means of autofecundation up to the generation F3. In this case, the resistant genes were also monitored through the inoculation with the pathotype 65 of C. lindemuthianum and the use of molecular markers: SCAR F101050a (Ur-ON and Co-10), SCAR BA8560a (Ur-ON and Co-10), SCAR AZ20845a (Co-4), SCAR Y20830a (Co-6), SCAR H13520a (Phg-1) and OPE04650a (Phg-2 e/ou Phg-5 e/ou Phg-6). The material to be achieved in the end of the improvement process initiated in this work, after being tested as to resistance and agronomic performance, will be able to be launched as a new cultivar and be used as a bank of resistance genes for more modern cultivars.