VIEW ARTICLE

Biochemistry and Cell Biology

Effects of Penicillium frequentans and Its Antibiotics on Unmelanized Hyphae of Monilinia laxa. A. De Cal, Department of Plant Protection, Centro de Investigacion y Technologia, Instituto Nacional de Investigaciones Agrarias (I.N.I.A.), Carretera de La Coruņa Km 7.5, 28040 Madrid, Spain; P. Melgarejo, Department of Plant Protection, Centro de Investigacion y Technologia, Instituto Nacional de Investigaciones Agrarias (I.N.I.A.), Carretera de La Coruņa Km 7.5, 28040 Madrid, Spain. Phytopathology 84:1010-1014. Accepted for publication 13 May 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-1010.

The effect of Penicillium frequentans and its antibiotics on the unmelanized mycelium of Monilinia laxa in culture has been investigated. An albino mutant of M. laxa obtained by ultraviolet radiation was utilized. Nonfungitoxic concentrations (10 ppm) of pyroquilon (1,2,5,6-tetrahydropyrrolo[3,2,1-if]quinolin-4-one) were also used to inhibit melanin biosynthesis in the pathogen. P. frequentans and its antibiotics induced a progressive lysis on unmelanized hyphae of M. laxa. After 14 days of incubation, more than 60% of these hyphae contained empty cells. At day 35, many hyphae were partially lysed. When 10 ppm of pyroquilon was added to the media, crude antibiotics also induced lysis on 24-h-old germ tubes. Unmelanized colonies showed poor production of macroconidia and microconidia. The significance of these findings is discussed.

Additional keywords: brown rot, integrated control, melanin inhibitors, stroma.