Fusarium oxysporum f. sp. lycopersici is a phytopathogenic fungus that causes vascular wilt in tomato plants. In this work we analyze the influence of metal salts such as iron and copper sulphate, as well as that of bathophenanthrolinedisulfonic acid (iron chelator) and bathocuproinedisulfonic acid (copper chelator) on the activity of laccases in the intra (IF) and extracellular fractions (EF) of the wild-type and the non-pathogenic mutant strain (rho1::hyg) of F. oxysporum. The results show that laccase activity in the IF fraction of the wild and mutant strain increased with the addition of iron chelator (53.4 and 114.32%; respectively). With copper, it is observed that there is an inhibition of the activity with the addition of CuSO for the EF of the wild and mutant strain (reduction of 82 and 62.6%; respectively) and for the IF of the mutant strain (54.8%). With the copper chelator a less laccase activity in the IF of the mutant strain was observed (reduction of 53.9%). The results obtained suggest a different regulation of intracellular laccases in the mutant strain compared with the wild type in presence of CuSO and copper chelator which may be due to the mutation in the rho gene.

Fusarium oxysporum f. sp. lycopersici is a fungus responsible for the tomato disease known as fusariosis. Enolase, which is the enzyme that catalyzes the reaction of 2-phosphoglycerate to phosphoenolpyruvate, is present during glycolysis. Enolase genes have been isolated from bacteria and fungi, among other organisms. In this research, a large portion of the enolase, eno, gene sequence was isolated from F. oxysporum and compared with those of other microorganisms, revealing a similarity of 51-69 %. We analyzed the copy number of the eno gene and determined that only a single copy is present in F. oxysporum, as in several fungi, such as Candida albicans and Aspergillus oryzae. We also detected the expression of the eno gene by reverse transcription-polymerase chain reaction during in vitro growth under two growth conditions where glucose was used as the carbon source, and we observed the same eno gene expression levels under both growth conditions.