The Interactive Effects of Temperature and Osmotic Potential on the Growth of Aquatic Isolates ofFusarium culmorum

Abstract

The mycelial growth of 10 Fusarium culmorum strains isolated from water of the Andarax riverbed in the provinces of Granada and Almeria in southeastern Spain was tested on potato-dextroseagar adjusted to different osmotic potentials with either KCl or NaCl (−1.50 to −144.54 bars) at 10 • C intervals ranging from 15 • to 35 • C. Fungal growth was determined by measuring colony diameter after 4 d of incubation. Mycelial growth was maximal at 25 • C. The quantity and capacity of mycelial growth of F. culmorum were similar at 15 and 25 • C, with maximal growth occurring at −13.79 bars water potential and a lack of growth at 35 • C. The effect of water potential was independent of salt composition. The general growth pattern of Fusarium culmorum growth declined at potentials below −13.79 bars. Fungal growth at 25 • C was always greater than growth at 15 • C, at all of the water potentials tested. Significant differences were observed in the response of mycelia to water potential and temperature as main and interactive effects. The number of isolates that showed growth was increasingly inhibited as the water potential dropped, but some growth was still observable at −99.56 bars. These findings could indicate that F. culmorum strains isolated from water have a physiological mechanism that permits survival in environments with low water potential. Propagules of Fusarium culmorum are transported long distances by river water, which could explain the severity of diseases caused by F.culmorum on cereal plants irrigated with river water and its interaction under hydric stress or moderate soil salinity. The observed differences in growth magnitude and capacity could indicate that the biological factors governing potential and actual growth are affected by osmotic potential in different ways.

Comparative study of the pathogenicity of seabed isolates of Fusarium equiseti and the effect of the composition of the mineral salt medium and temperature on mycelial growth

“…Studies on the mycelial growth of F. solani and F. culmorum strains isolated from water or seabeds of the southeastern coast of Spain indicate that some Fusaria have the capacity to adapt metabolically to environments with low osmotic potential (21,23). Further studies on Fusarium spp.…”

Un síndrome asociado a Fusarium oxysporum y a la salinidad del agua de riego que causa la muerte de plantas de tomate en Almería (Sureste de España)

“…Así ha sido propuesto para Phytophthora por Blaker y Mac Donald (1985); Para Penicillium, Aspergillus, Fusarium por Tresner y Hayes (1971); para Fusarium oxysporum f. sp. vasinfectum (Ragazzi y Vecchio, 1992); para Fusarium culmorum (Palmero et al, 2009) y para F. oxysporum (Palmero et al, 2010), y además se han apreciado cambios en el comportamiento de estos hongos cuando se desarrollan en un medio con alta salinidad (Ragazzi et al, 1994;Palmero et al, 2010).…”