Resistência de plantas hospedeiras e identificação de genes diferencialmente expressos na interação soja - Phakopsora pachyrhizi

• Autor(a) principal: Nogueira, Sônia Regina
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1010
• topic: Resistência; Soja; Phakopsora pachyrhizi; Resistance; Soybean; Phakopsora pachyrhizi; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA

The Brazilian soybean production accounts for 25% of the world production. The soybean asian rust caused by Phakopsora. pachyrhizi is one of the most important fungal disease of this crop. However, there are few studies available related to the biology of the fungus and its host range. Thus, this work aimed to identify soybean genes differentially expressed in the soybean-UFVS 2002 P. pachyrhizi interaction, and to evaluate the resistance of 55 genotypes of cowpea (Vigna unguiculata (L.) Walp), 55 of pigeon pea (Cajanus cajan (L.) Millsp.) and 13 of the common bean (P. vulgaris L.) to the isolate PPUFV01. Two subtractive libraries enriched for genes differentially expressed in soybean in response to P. pachyrhizi, at 2 and 9 days after inoculation, were built. ESTs were identified with similarity to defense response genes, stress response genes, basal metabolism- related genes and genes with unknown function. Analysis of differential expression by RT-qPCR of 25 genes selected showed that 14 were induced in response to infection by the pathogen, including genes that codes for proteins PR4, thioredoxin, quitinase 1, R14, calmodulin, catalase, hemeoxigenase and RD22; functional studies must be carried out to confirm and quantify the function of these genes in the interaction. Host resistance analyses identified 5 types of reaction in the genotypes evaluated, ranging from immunity to susceptibility reactions similar to what occurs in soybean. In general, all the cowpea genotypes were resistant, and it was not observed genotype with TAN type lesion, indicative of susceptibility. In pigeon pea, genotypes ranging from immune to completely susceptible were identified; the susceptible genotypes had sporulating level similar to what is observed in soybean. No common bean genotype presented immunity reaction, with resistant and susceptible genotypes being identified, although with lower than suscetiple soybean. Common bean and pigeon pea can be important reservoirs for fungus maintenance in the field in the absence of soybean plants as well as important alternative sources of resistance genes to P. pachyrhizi.