Monthly Archives: August 2019

8”S, 50°11′9 8”W), São Francisco de Paula, Rio Grande do Sul, Bra

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8”S, 50°11′9.8”W), São Francisco de Paula, Rio Grande do Sul, Brazil, in April 2009. The cones

were disassembled into single seeds, which were disinfected with sodium hypochlorite (2% active chlorine) for 20 min, followed by 0.3% Benlate fungicide (Dupont, Belle, WV, US) for 10 min, and rinsed with sterile distilled water. The seeds were then placed in polyethylene bags and maintained at 0°C until use. Seeds were placed on sterile filter paper embedded in 10 ml of sterile distilled water in Petri dishes, and allowed to germinate. After the start of germination (day 0), seedlings were transferred to polyethylene jars (1.9 l) containing moist sterile vermiculite. The jars were kept wet by the addition JNK-IN-8 cost of 100 ml of sterile distilled water at 10-day eFT508 intervals. All jars were kept at 25

±2°C with light intensity of 31 μmol m-2 s-1 in a 16-h photoperiod. The natural occurrence of the pathogenic fungus and plant mortality were evaluated at days 50 and 150. The evaluation period was chosen according to the pattern of depletion of seed reserves. The plant growth is strongly dependent on carbohydrate import from seed until 70 – 80 days after germination [17] and the seed CH5424802 reserves are apparently exhausted approx. 100 days after planting [40]. Isolation and culture of the fungal pathogen Fungal infection was not observed on seeds before they had developed. The first disease symptoms consisted of cotyledon browning and abscission, followed

by browning and hardening of the megagametophyte. The fungus was isolated from about 50-days-old seedlings. For this purpose the megagametophyte and the cotyledons were removed, superficially disinfected in 96% ethanol (1 min) and submersed in 1% sodium hypochlorite for 10 minutes. The material was desiccated in a laminar flow bench and the megagametophyte Cytidine deaminase was separated from the cotyledons. Infected tissues were transferred to tubes with PDA medium (potato dextrose agar, Acumedia Manufactures, Inc. Lansing, MI, USA) using a sterile platinum loop. Tubes were incubated at 26°C for 7 days and examined for fungal growth. The emerged fungus was transferred to fresh PDA medium. Continuous culture was on ISP-2 agar [41]. The microorganism was found in all plants showing symptoms of infection. The pathogenicity test was performed by using healthy seeds excised from mature cones collected in 2011. Seeds were disinfected as previously described and scarified by removing the integuments from the seed tip [40], exposing the megagametophyte. Scarified seeds were incubated at 25°C in darkness with the fungus. For this purpose, seeds were placed in a tray and partially covered with sterile water containing mycelium. Mycelial plugs (1.5 cm diameter) of 14-day-old cultures of the isolate were homogenized in 10 ml sterile water. Controls consisted of sterile water, supplemented with an agar plug without fungus. Trays were maintained on an orbital shaker (50 rpm) for 48 h.