Morphological and molecular identification characterization of Neopestalotiopsis species associated with Leaf Spot on Oil Palm (Elaeis Guineensis Jacq.)

Abstract

Common phytopathogens from several genera, Annellophora, Bipolaris, Cercospora, Curvularia, Colletotrichurn, Calonectria, Exserohilum, Gliocladium, Pestalotiopsis, Pestalotia, Phaeotrichoconis, Pseudocercospora, and Stigmina can cause Leaf Spot Diseases in tropical and subtropical plants (Elliott 2005). Leaf Spot is considered as a minor disease, but it can spread rapidly during the long period of high rainfall and high humidity. The living leaves of oil palm are the main part that the Neopestalotiopsis species will infect at any growth's stages. Spots are most often yellowish to brownish, which appear as round to ovals and overtime the spots may enlarge to form blotches. This disease not only affects the mature stage of Oil Palm, but also Oil Palm seedlings. The small planted Oil Palms with to trunk and few leaves are at risk of suffering damage if they are severely affected by the leaf spots. Species of Neopestalotiopsis, a new genus is a sister clade to Pestalotiopsis. Pestalotiopsis is also a common phytopathogen that can cause Canker, Chlorosis, Fruit Rots and Post-Harvest diseases (Crous et al. 2001). Species of Neopestalotiopsis occur commonly as plant pathogens, and can be found on many different substrates. Most the species belong to the genus Neopestalotiopsis cause Leafs Spots and tip dieback, and they can be easily identified based on morphological and molecular characteristics. Species belong to the genera Pesta/otiopsis and Neopestalotiopsis show similar conidial morphology such as conidial length, width, median cell length, colour of median cells and the length of the apical appendages. According to Taylor 2001, Neopestalotiopsis species that have been isolated from Proteaceae plants especially Floriculture plants is prevented at the quarantine entry border. In the present study we examined one Neopestalotiopsis fungal species, which was isolated from oil palm and Malaysia origin. Phylogenetic relationship between isolated strain and its relative species is resolved based on analysis of internal transcribed spacer (ITS) rRNA gene sequence data. Isolated fungal species from leaf spots of oil palm in this study is therefore allocated to Neopestalotiopsis genus. Phylogenetic analyses of ITS sequence data supplemented with conidial morphology clarify the species identity in the Neopestalotiopsis genus.