Morphometric Variation of Phytophthora palmivora Causing Black Pod Rot Disease on Cocoa ( Theobroma cacao L.) in Indonesia

摘要

Background and Objective: Black pod rot disease caused by Phytophthora palmivora is one of factors contributing in decrease of cocoa production in Indonesia. This research was conducted to study the variation of P. palmivora causing black pod rot disease in Indonesia based on morphological characteristics and sexual reproduction. Materials and Methods: Pathogen was isolated from cocoa pods showing black rot symptoms in Indonesia for morphological and sexual characterization as well as molecular confirmation. Quantitative data of sporangial and sexual features were recorded and arranged in multivariate as well as calculated using phonetic method with hierarchical cluster. Those characters were clustered through average linkage and reconfirmed with principal component analysis (PCA) and dendrogram using NTsys 2.10e program. Results: Fifty-five isolates of pathogenic agents had been successfully collected from 38 regencies (23 provinces) in Indonesia. They had various sporangial shape, i.e., distorted, ellipsoid, globose, obpyriform and ovoid as well as and spherical chlamydospores. These features were recognized as the characteristics of Phytophthora palmivora . Molecular analysis confirmed that all isolates were positively detected with multiplex PCR using species-specific primers. Sexual reproduction was characterized with the formation of amphigynous antheridia as well as spherical oogonia and oospores in which A2 type occurred more frequently thanA1 type. Conclusion: Those isolates were classified into 8 clusters which were independent with geographical area and mating types.