<p>ABSTRACT</p><p><br />Molecular and biochemical characteristics of Fusarium oxysporum f.sp. cubense (Foc) were detected. Six of Indonesian Foc isolates were artificially inoculated on “Ambon Kuning” banana. DNA of one-week culture isolates was extracted by three methods prior to PCR assay using Foc TR4 (tropical race 4) specific primer. Activity of extracellular enzyme was determined with reduction sugar, agar diffusion and SDS-PAGE assays. Statistical analysis revealed that all isolates insignificantly caused Fusarium wilt symptoms on tested banana with <br />disease severity index ranging from 3 to 3.6. Maximum DNA concentration was obtained by CTAB method (766.25 µg mL-1), followed by SDS and alkaline l ysis methods, i.e. 553.75 and 211.25 µg mL-1, respectively. PCR analysis showed that Bnt2 and Kjg1 isolates positively reacted to TR4 of Foc primer (DNA size of 1400 bp approximately). Reduction sugar and agar diffusion assays demonstrated that Kjg1 isolate significantly produced more extracellular enzyme, with 6.53 × 10-2mg mL-1 in conce ntration and 20 mm in halo diameter. Meanwhile, SDS-PAGE assay viewed diverse bands of tested fungi (20.6 to 80 kDa), representing four extracellular enzymes. Positive PCR results highlighted the presence of Foc TR4 infecting banana in Indonesia. Various activities of extracellular enzymes did not influence the pathogenicity of Foc.</p><p>Key words: pathogenicity, DNA concentration, extracellular enzyme</p>
Indonesia is an agricultural country with more than 30 million farmers nationwide most of it with poor disease management. An identification of a pathogen is the first step to establish efficient management strategies for disease control. In this study, we survey the diversity of oomycetes in horticulture. Samples were collected from 19 sites around Lampung, Sumatera and Java Islands. The oomycetes were isolated from rhizosphere soils sample and from symptomatic plants tissues. One hundred and twelve isolates belonging to two Phytophthora spp., three Pythium spp., and one Phytophythium sp. were identified. Phytophthora nicotianae was a predominant species from pineapple but also found in cabbage, chilli, and chrysanthemum. P. colocasiae were isolated from taro in central java, Phytopythium vexans were isolated from potato in Central Java, while Pythium acanthophoron, Py. myriotylum, Py. splendens, and Py. catenulatum were isolated from soil in pineapple farms.
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