ISOLATION AND IDENTIFICATION OF Taphrina caerulescens IN Quercus eduardii IN AGUASCALIENTES, MEXICO

Abstract

Taphrina caerulescens exclusively affects plants of the Quercus genus. The identification and isolation of this fungus is difficult due to its dimorphic nature and extremely slow growth habit in artificial growth media. The objective of this research was to isolate and identify the fungal pathogen T. caerulescens. Three methods were used to isolate the fungus, however, only the spore fall method was successful. In order to identify the fungus, a visual inspection of the host plants infected leaves was carried out. The symptoms and signs of infection were noted. In addition to the typical blister formation on the infected leaves, an atypical symptom comprising of chlorotic spots covered with asci was also observed. Three biochemical tests were carried out to prove that the pathogen was in the genus Taphrina: The first, tested the ability to utilize urea, the second, its capacity to produce extra cellular DNase, and the third tested its reaction to Diazonium blue B (rapid blue salts). For species identification the following analyses were carried out: 1) carbon assimilation tests using the glucose, saccharose, D-xylose, raffinose, trehalose and sorbitol, as carbon sources; 2) molecular analysis tools were utilized to extract and sequence the genomic DNA. The resulting sequences when analysed with the NCBI Nucleotide blast tool confirmed, with 99% similitude, that the isolate was similar in nature to T. caerulescens strain CBS 351.35 ascension number AF492081.1. Pathogenicity test was also carried out and resulted in the infection of 25 % of the inoculated plants.