THE USE OF ERGOSTEROL IN THE PATHOGENIC FUNGUS BIPOLARIS-SOROKINIANA FOR RESISTANCE RATING OF BARLEY CULTIVARS

Ergosterol content in the plant pathogenic fungus Bipolaris sorokinian a was determined in different matrices including mycelium, spores, cul ture filtrate and infected barley leaves. Ergosterol was extracted wit h methanol, hydrolysed with KOH and quantified by reverse phase high p erformance liquid chromatography (HPLC). Our procedure was used to stu dy how the ergosterol concentration of B. sorokiniana varied due to fu ngal age and nutrient availability when growing in liquid medium. It w as found that the ergosterol content decreased with fungal age. The de crease was not due to leakage. It was also found that a change to a le ss nutrient-rich medium caused an increase in ergosterol content where as a change to a rich medium led to a decrease. The procedure was also used for quantification of fungal infections in complex matrices (e.g . leaves). The development of fungal infection in barley leaves was fo llowed during 10 days. Visual grading of leaf spots was also compared to ergosterol content in three varieties of barley. The ergosterol con tent in the leaves increased exponentially until day 7, and the gradin g of the leaf spots was correlated to the ergosterol content. Our resu lts show that, despite a great variation, ergosterol may be used as a biomarker to detect and quantify fungal infections in a given matrix.