Dianthibiological aspects of one fungi rhizoctoniaand its in vitrointeraction withfusarium oxysporum f. sp.dianthi

Abstract

ABSTRACTGrowth in different culture media and temperature as well as its antagonic roleagainst Fusarium oxysporumSchlencht f. sp. dianthi(Prill and amp; Del) Snyder and amp; Hansen, werestudied on an isolated of the fungi Theobroma grandiflorum(Spreng) K. Schum. Lowgrowth and the presence of abundat moniloid cells were detected when the fungi wascultured in PDA in microculture, with natural light and at 20ºC. Higher temperatures(27ºC and 30ºC) increased growh rate. When cultured at 20ºC, in darkness, similarresults as those recorded at 30ºC in natural light were found. After a month sclerotiagrotwh was present. Culture in AMS in Petri dishes, with natural light at 20ºC showedgrowth in patches which suggests phenotype variability. Poor growth was recordedwhen cultured in AAg. Our results showed that rapid and vigorous growth isobtanined when the fungi is cultured in PDA at 30ºC in darkness producing conidiaand sclerotia. T. grandiflorumalso has an antagonic role against F.oxysporumsp. dianthi,growing faster and inihibitingits growth.

Se estudiaron diferentes aspectos de la biología de un hongo aislado de Theobromagrandiflorum(Spreng) K. Schum, tales como su comportamiento como antagonista encondiciones in vitrocon Fusarium oxysporum Schlencht f. sp. dianthi(Prill y Del) Snyder yHansen. Se encontró que el hongo cultivado en PDA, condiciones de microcultivo y luznatural a 20ºC crece lentamente y produce abundantes filamentos monilioides; a 27ºCy 30ºC, crece rápidamente. En condiciones de oscuridad a 20ºC, los resultados sonsimilares a los obtenidos a 30ºC en luz natural. Al término de un mes, el hongo produceesclerocios. En AMS, en cajas de Petri, luz natural y a 20ºC, se observan "sectores" muybien delimitados, lo que indica una fuerte y evidente variabilidad genética, demostradaen cambios fenotípicos. En AAg, el hongo crece pobremente. Los resultados obtenidosindican que en PDA, 30ºC y condiciones de oscuridad, este hongo, Rhizoctonia sp., crecerápida y vigorosamente, produciendo abundantes conidias en sus esclerocios. Con rela-ción a su comportamiento in vitrofrente a Fusarium oxysporumScht. f. sp. dianthi, Rhizoctoniaspcrece con mayor rapidez y agresividad que Fusarium oxysporum, llegando a inhibirlo.