Percorrer por autor "Offerman, J."
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- In vitro culture conditions of Colletotrichum gloeosporioides for spore production: a) Effect of medium composition and light on spore productionPublication . Offerman, J.; Sousa, Maria João; Rodrigues, Paula; Martins, Anabela; Dias, AlbertoColletotrichum gloeosporioides, the imperfect stage of the ascomycete Glomerella singulata, is responsible for anthracnose in a wide variety of plant species. Hypericum perforatum, which is responsible for the synthesis of hypericin, a metabolite with important pharmaceutical applications, is one of the species sensitive to C. gloeosporioides. Since H. perforatum tolerance to C. gloeosporioides is dependent on plant variety, we intend to select tolerant varieties in vitro for metabolite production without fungicide application. C. gloeosporioides spores are needed to inoculate and induce a selective pressure on plants, but in vitro sporulation is particularly difficult to achieve. The establishment of in vitro conditions for sporulation was the main goal of the trials here presented. Two variables were tested for C. gloeosporioides spore production: medium composition and light. The effect of medium composition was tested by growing the fungus in PDA (Potato Dextrose Agar) and MMN (modified Melin & Norkrans). We also tested the influence of moving the fungus from PDA to MMN and vice-versa. Growth and spore formation was recorded for a period of three months. Light influence was tested by submitting the fungus to light and dark conditions, for both media. Growth and spore formation under these conditions was recorded for a period of two months. Preliminary results showed PDA to be a better medium for spore production in C. gloeosporioides. The presence or absence of light did not influence spore production.
- In vitro culture conditions of colletotrichum gloeosporioides: b) Effect of temperature shock on spore productionPublication . Offerman, J.; Sousa, Maria João; Rodrigues, Paula; Martins, Anabela; Dias, AlbertoHypericum perfuratum is an important plant species used for the production of hypericin, a metabolite of major application in the pharmaceutical industry. Its production is, however, strongly limited by Colletotrichum gloeosporioides, the causative agent of anthracnose. As H. perforatum tolerance to C. gloeosporioides is dependent on plant variety, we intend to select tolerant varieties under in vitro conditions for metabolite production without fungicide application. Selective pressure on plants is induced by inoculation with the fungus spores, but spores are difficult to obtain. The establishment of in vitro conditions for spore production was the main goal of the trials here presented. The influence of changing temperature on spore production of C. gloeosporioides was tested. Four different temperature conditions were tested, using the environment temperature as reference. We tested the influence of an initial cold and heat shock, as well as a cold and heat shock after growth under environment conditions. Preliminary results showed that an initial heat shock induces spore production in C. gloeosporioides. Complementary trials on spore production and in vitro plant inoculation are being developed.