Resistência do feijão-comum à murcha-de-fusário: Metodologias de inoculação e de avaliação

• Ano de defesa: 2013
• Autor(a) principal: Pereira, Alisson Campos
• Orientador(a): Carneiro, José Eustáquio de Souza
• Banca de defesa: Souza, Moacil Alves de , Vieira, Rogério Faria
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Phaseoulus vulgaris; Fusarium oxysporum; Resistência; Metodologias de inoculação; Metodologias de avaliação
• Palavras-chave em Inglês: Phaseoulus vulgaris; Fusarium oxysporum; Resistance; Methods of inoculation; Methods of assessment
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1387

We conducted four experiments to efficiently identify common bean lines resistant to Fusarium wilt. The specific objectives were to develop and compare assessment methodologies, evaluate inoculation methodologies, identify sources of resistance to Fusarium wilt and obtain information in respect to the process of infection from Fusarium oxysporum f. sp. phaseoli (Fop). Thus, we first developed a new scale for assessment of the severity of Fusarium wilt (healthy control plant relative scale HCPR) which, in addition to the typical Fusarium wilt symptoms (death, leaf wilting and chlorosis and dwarfism), considers the symptom of reduction in common bean growth. The results obtained through this scale were compared to the results obtained through four scales already described in the literature. For that purpose, we set up an experiment with 15 lines of common bean using a randomized block design with four replications, each plot consisting of a pot with three plants. Assessments were made at 21 days after inoculations (DAI). According to the results obtained, the HCPR scale is more precise than the previously described methodologies. In a subsequent methodologies of inoculation (February/March (hot season of second Fop experiment, in two we compared environmental HS) and June/July (cold season four conditions CS)). The lines Manteigão Fosco 11, VP8 and Meia Noite were used in this experiment. The experimental design was randomized blocks with three replications, and plots consisted of two pots with three plants. Assessments of the severity of Fusarium wilt took place every three DAI, through use of the HCPR scale developed in the first experiment. The most suitable time period for assessment of the severity of Fusarium wilt was at 22 and 37 DAÍ in the hot and cold periods of the year, respectively. The inoculation methodology that best discriminated the lines was cutting 1/3 of the root length, followed by immersion in the Fop conidium suspension for 5 minutes. In the third study, using the HCPR scale from the best inoculation methodology and assessment time according to the previous experiments, we phenotypically characterized 197 common bean elite lines assessed in the Value for Cultivation and Use (VCU) trials in Minas Gerais in the period from 2002 to 2012 in regard to reaction to Fusarium wilt. A randomized block design with two replications was used. Each plot consisted of a pot with three plants. Of the 197 lines assessed, 29 proved to be resistant. After identifying sources of resistance, we conducted a fourth study where we sought to understand the process of infection from Fop. For that purpose, we used the lines Manteigão Fosco 11 (resistant), VP8 (intermediate) and Meia Noite (susceptible). At 43 days after inoculation, stem segments were observed in a scanning electron microscope. The lines Manteigão Fosco 11 and VP8 exhibited material occluding the xylem vessels, which possibly restrict colonization by Fop. Apparently, resistance of common bean lines to Fop may also be explained by greater compaction of xylem cells.