Caracterização genética da resistência ao míldio (Peronosclerospora sorghi) em sorgo (Sorghum bicolor L. Moench)

• Ano de defesa: 2008
• Autor(a) principal: Simões, Christiano Costa
• Orientador(a): Moreira, Maurílio Alves
• Banca de defesa: Guimarães, Cláudia Teixeira , Barros, Everaldo Gonçalves de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Bioquímica Agrícola
• Departamento: Bioquímica e Biologia molecular de plantas; Bioquímica e Biologia molecular animal
• País: BR
• Palavras-chave em Português: Resistência ao míldio; Sorgo
• Palavras-chave em Inglês: Resistance to the downy mildew; Sorghum
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/2403

In this work, were assessed 13 strains of sorghum from the breeding program of the Embrapa Maize and Sorghum about the reaction to nine races of Peronosclerospora sorghi. Among the lines were identified five sources of resistance to nine races (BTx623, Tx430, SC414-12, QL-3 and ARG- 1),two lines (SC283 and ATF14B) that were susceptible to the same races, and six lines with a variable reaction of resistant and susceptibility depending upon the race inoculated. The five sources of resistance were crossed with the susceptible line ATF14B and F1's selfed to generate F2 populations with 150 individuals. For Chi- square test to 5% level of probability, it was determined that the lines SC414-12, BTx623 and Tx430 had two dominant and independent genes, while the lines QL-3 and ARG-1 had only one gene for resistance to each the six most i races of P. sorghi . Based on the frequency of resistant and susceptible individuals in populations derived from dialelic crosses between sources of resistance there is a strong possibility that the lines QL-3 and ARG-1 have the same gene for resistance to six races of P. sorghi as no susceptible plant was identified in the F2 generation between these two crosses. However, by limiting the population size could not be concluded on the number of genes segregando between resistant strains, suggesting the existence of epistatic effects of complementarity between genes and / or differences in genetic background. A population of 121 recombinant strains caused the crossing and a lineage likely BTx623 (IS3620C) was phenotyped by the reaction to the same six races, and detected the presence of two dominant genes for resistance in line BTx623 to the races 04A, 16A, 22A and 22B . Assessing the coincidence of the reaction of susceptibility / resistance in the population of RILs, it seems that one of the resistance genes in line BTx623 confers resistance to races 04A and 16A as the races 22A and 22B also have their resistance due to action of a gene in common. On the other hand, there was no common genes conferring resistance to races 16A and 22A. Thus, the set of data provides subsidies for the use of sources of resistance to brown rot sorghum, allowing the combination of resistance genes vertical and broad spectrum of specific genes to the races in the breeding program. Additionally, people are judged ready for the mapping with molecular markers. The future of these markers association with the resistance to downy mildew sorghum and their effective implementation assisted in the selection for resistance to downy mildew in sorghum is of great interest for the breeding program of the Embrapa maize and sorghum.