Ultrastructural changes in blastospores of Taphrina caerulescens in the presence of a susceptible and non-host species

Abstract

Taphrina caerulescens is a fungal pathogen of oak trees, it causes the disease leaf blister in 50 reported Quercus spp. In 2015, the fungus was isolated for the first time from Quercus eduardii, an oak species endemic to the Sierra Fria of Aguascalientes, Mexico. The objective of this study was to document the changes that occur in the inoculum prior to infection of its host as it changes from saprophytic to parasitic. Two host plant species were used: Q. eduardii and Q. potosina and one non-host species Pittosporum tobira. Portions of leaf tissue 24 h, 48 h and 72 h post inoculation with a suspension of T. caerulescens conidia were analysed with a scanning electron microscope. Moderate budding was observed after 24 h on Quercus samples; after 48 h increased budding on both Quercus spp. and the formation of blastospores significantly smaller than the original inoculum was observed on the Quercus eduardii samples. Formation of germ tubes was verified after 48 h on Quercus eduardii. The germinative tubes were observed growing randomly towards the stomata. No significant changes were observed on the surface of the non-host samples. There is no other report of these smaller blastospores in T. caerulescens.