Acquired resistance to pimaricin in Cladosporium cucumerinum and Fusarium oxysporum f.sp. narcissi associated with decreased virulence

Abstract

In laboratory experiments strains of Cladosporium cucumerinum and Fusarium oxysporum f.sp. narcissi were selected, which showed resistance to the fungicidal antibiotic pimaricin. Increased resistance appeared associated with decreased fitness in vitro (radial growth and sporulation on agar media) and in vivo (pathogenicity). The physiological background of a link between sensitivity to the fungicide and pathogenicity is discussed.

Methods for Detecting and Monitoring the Resistance of Plant Pathogens to Chemicals

“…For new introductions with limited use in the field, such as iprodione, imazalil, procymidione and vinclozolin, continued monitoring may determine whether or not resistance will develop in practice. Venturia (Leben et al, 1955) Pyricularia (Uesugi, 1969) Physalospora (Taylor, 1953) Pyricularia (Yamasaki et a1., 1964) Botrytis cinerea (Parry and Wood, 1959) PUccinia graminis (Polyakov and Mende, 1965) UstiZago (Ben-Yepeth et a1., 1974) Aspergillus (Van Tuy1, 1975) Aspergillus (Gunati11eke et a1., 1975) Ustilago (Tillman and Sisler, 1973) Botrytis (Sakurai, 1977) Monilinia (Mader and Schneider, 1948) Cochliobolus (MacKenzie et a1., 1971) SahizophyZZum (Pika1ek et al, 1978) AspepgiZZus (Dekker, 1972) Bot~tis (Leroux, 1977) Pythium (Halos and Huisman, 1976) AspepgiZZus (De Waard et al, 1977) Cepaospopa (Giannopo1itis, 1978) Bot~tis (Parry and Wood, 1959) AspepgiZZus (Van Tuy1, 1977) SaZepotium poZfsii (Anilkmar, 1976) Epwinia (English and Van He1sema, 1954) PypiauZaPia (Yoshii et a1., 1958) AspepgiZZus (Van Tuy1, 1977) CZadospopium (Dekker et al, 1979) Fusapium (Dekker et a1., 1979) MoniZinia (Good and MacNeill, 1972) (continued) Fusarium (Vanachter, 1977) Rhizoctonia (Vanachter, 1977) Sclerotinia (Wolfe, 1971) Sphaerotheca (Gilpatrick and Provvidenti, 1973) Cladosporium (Fuchs et al, 1977) Botrytis (LeRout, 1977) Monilinia …”

Decreased sensitivity to pyrazophos of cucumber and gherkin powdery mildew

“…This might be due to instability of the resistance, or to a decreased fitness of the resistant isolate, as was earlier found for pimaricin resistant isolates of Cladosporium cucumerinum (Dekker and Gielink, 1979). From the present experiments it appeared that in absence of the fungicide, the pyrazophos-resistant isolate was less fit than the original, sensitive pathogen.…”

Comparative Study of a Semisynthetic Derivative of Natamycin and the Parent Antibiotic on the Spoilage of Shredded Cheddar Cheese

“…Mutants lose the ability to demethylate C-14 methyl groups by oxidation in the biosynthesis of ergosterol. A primitive biogenetic precursor, 14-.-methyl sterol, is incorporated in place of ergosterol in the cell membrane (Dekker and Gielink, 1979;Ziogas et al, 1983). All but one study, indicate a decrease in ergosterol content for resistant C. albicans.…”

“…Resistance to polyene antibiotics may be due to a single gene mutation. Woods (1971) showed this effect for nystatin resistance in yeasts and it was later shown for natamycin resistance in A. nidulans (Dekker and Gielink, 1979).…”

“…The quantitative and qualitative alterations in the sterols of the fungal membrane responsible for reduced affinity to polyene antibiotics, seem at the same time to lower the fitness of mutants which are resistant to these antibiotics" (Dekker and Gielink, 1979). If mutation for resistance would occur in clinical conditions it is improbable or impossible that these organisms would be able to establish appreciable numbers.…”