Mechanisms of Pathogenesis of Angular Leaf Spot of Red Kidney Bean (Phaseolus vulgaris L)

Abstract

The penetration of the fungus Phaeoisariopsis griseola (Sacc.) Ferraris was an indirect penetration. Within 48 hours after inoculation, the conidia on red kidney bean leaf surface germinated germ tube and formed appressorium at the penetrated through stomata. Infected hypha grew in substomatal cavity and expanded to reach mesophyll, parenchyma, palisade and epidermis cells. It later ramified extensively in intercellular space. Disease symptom firstly appeared in the form of pale yellowish spot ten days after inoculation and subswquent growth of infected hypha was intracellular. Hypha was aggregated to form stroma in substomatal cavity. Conidiophore was produced and emerged from stomata to produce conidia. Sporulation was completed within 4 days after disease symptom appeared.