Host respostas transcricionais para vasculares e foliar fungos fitopatogênicos

• Autor(a) principal: Almeida, Robson Ferreira de
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1123
• topic: Interação plant-patógeno; Mecanismos de defesa; Microarranjo; Biblioteca subtrativa; Hemileia vastatrix; Verticillium longisporum; Plant-pathogen interaction; Defense mechanisms; Microarray; Subtractive library; Hemileia vastatrix; Verticillium longisporum; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

We used a comprehensive approach for the dissection of genetic mechanims controlling plant responses to phytopathogenic species of the genus Verticillium. V. dahliae (Vd) and V. longisporum (Vl) are soil fungi causing vascular diseases in herbaceous plants and trees that result in billions of dollars in annual losses worldwide. The pathogens lack a high degree of host specificity and can colonize and multiply in several different plant species. At the present, there is little or no knowledge of the deterministic molecular and genetic basis of plant resistance/tolerance to Verticillium spp. To address this knowledge gap, we studied the interaction of Vl with the model plant Arabidopsis thaliana. Microarray experiments and metabolite analysis indicated that Vl but not Vd isolates were able of reprogramming the tryptophan (Trp) metabolic pathway resulting in lack of accumulation of the Trp-derived defense compounds indolic glucosinolates (IGs). We are proposing that the Vl pathogenicity strategy involves recruiting the transcription factor WRKY 70 as negative regulator of the IG biosynthesis This part of the thesis was developed at Dr. Paola Veronese's lab at NCSU (North Carolina State University). We also studied the molecular mechanism involved in coffee's plant response against the phytopathogen Hemileia vastatrix. We focused on the identification of genes involved or related with coffee resistance to orange rust caused by the fungi Hemileia vastatrix . This part of the thesis was developed at Biocafé/Bioagro/UFV (Federal University of Vicosa). The methodology used for the isolation of genes involved in resistance was the suppression subtractive hybridization (SSH), which is based on a preferential amplification performed by the polymerase chain reaction (PCR) of differentially represented sequences in two cDNA populations, and prevention of the amplification of common sequences by suppression event. We used in the present work the Timor Hybrid CIFC 832/2 genotype. Leaves of this genotype were inoculated with uredospores of Hemileia vastatrix (race II). After inoculation, the RNA was extracted from leaves (at 12 and 24 hs) to proceed the suppression subtractive hybridization. We also studied the expression of two genes (cysteine protease and chitinase) by quantitative RT-PCR in two different genotypes, CIFC 832/2 (resistant to H. vastatrix) and Catuaí (susceptible to H. vastatrix). The result showed different patterns of expression of these two genes between these two genotypes. The expression of the two genes in the Timor Hybrid CIFC 832/2 was higher and earlier than was in the Catuaí IAC 44 genotype.