IDENTIFICACIÓN DE ESPECIES DE Fusarium AISLADAS DE SEMILLAS SINTOMÁTICAS Y ASINTOMÁTICAS DE MAÍZ CON BASE EN EL GEN TEF-1α

A phytosanitary problem in maize (Zea mays L.) is ear rotting due to fungi belonging to the Fusarium fujikuroi complex. The typical symptom of the disease is the presence of rotten seeds randomly distributed on the ear. Frequently, the plant breeder selects plants that produce healthy ears, which sometimes contain a few seeds with symptoms, assuming that the asymptomatic seeds are free of the pathogen. The objective of the present study was to identify Fusarium species in both symptomatic and asymptomatic seeds from the same ear, based on the phylogeny of a region of the 1α translation elongation factor (TEF-1α). Ears from seed production plots from 14 locations of five states of Mexico were used: 28 ears from Chiapas, 16 from Chihuahua, 10 from Guanajuato, 14 from the State of Mexico and 16 from Jalisco. Seeds of each type were disinfested and placed in culture medium. After 5 d mycelium and conidia growth was observed, of which three were selected from each isolate, transferred to PDA medium and their coloration (white, salmon, purple, violet or red) was registered. Four hundred and thirtynine strains were obtained. The predominant color of the mycelia was white. Fifty-four percent of the total strains came from symptomatic seeds and the rest from asymptomatic ones. In each state, the number of strains from each type of seed was similar. In both cases, Fusarium subglutinans, F. temperatum and F. verticillioides were identified. In addition, for the first time in Mexico, the presence of Haplotypes 10 and 11 of the latter species was detected. The breeder is at the risk of selecting germplasm susceptible to rot when choosing plants that produce ears in which both types of seed coexist.