Christanti Sumardiyono

Identification of purple blotch pathogen of shallot by PCR using specific primer for Alternaria genus

Abstract Purple blotch (Alternaria porri), having symptom similar to stemphylium blight (Stemphylium vesicarium), is one of the important diseases that significantly lowered shallot yield in Indonesia. However, stemphylium blight has never been reported. Purple blotch pathogens from farmers’ crops in Bantul and experimental crop in Centre of Innovative Agricultural Technology Universitas Gadjah Mada (CIAT-UGM) Sleman Regencies were identified to observe whether Stemphylium sp. was found with A. porri. Thirteen isolates obtained showed variability in colony texture, colour and pigmentation. DNA fingerprinting through Polymerase Chain Reaction of BOX and Enterobacterial Repetitive Intergenic Consensus region dispersed those isolates into two main groups. Identification using Alternaria-specific primers, Dir1ITSAlt/Inv1ITSAlt revealed that 10 isolates were Stemphylium sp. and 3 isolates were Alternaria sp. A. porri was only identified from CIAT-UGM. This finding emphasise that the Alternaria-specific primer was able to amplify Stemphylium sp. Besides, stemphylium blight disease may have been occurred in farmers’ crops in Bantul.

Induction of Reactive Oxygen Species by Trichoderma spp. Against Downy Mildew in Maize

Downy mildew is the most important disease in maize and causes severe loss of maize productivity. Trichoderma spp., which can be used as biocontrol agents and plant inducers, could induce reactive oxygen species (ROS). This study aimed to know the potency of Trichoderma spp. in inducing downy mildew disease and inducing ROS. The production of ROS is one of the earliest cellular responses following successful pathogen recognition. There were four Trichoderma isolates in this study: JMA1, JMA2, KMA, and STA. The results showed that KMA, STA, JMA2, and JMA1 isolates significantly reduced disease intensity and the incidence of plant disease. Trichoderma spp. induced ROS as a response of plant resistance against downy mildew.

Pengimbasan Ketahanan Pisang terhadap Penyakit Layu Fusarium dengan Asam Salisilat In Vitro

Salicylic acid (SA) is an important signal in plant defense. It is used as induced resistance agent against Fusarium wilt. An artificial induction was conducted by shaking the shoot groups of banana tissue culture in liquid medium of Murashige-Skoog (MS). MS medium was added with 0 ppm (as control), ⅛ LC50, ¼ LC50, ½ LC50, and LC50 concentration of SA. Alive shoot groups were subcultured for about three months and were acclimated. Resistance test had been conducted in glass house by inoculated six months old banana seedlings with Fusarium oxysporum f.sp. cubense (Foc). Leaves symptom were observed based on Leaf Symptom Index (LSI) and corm discoloration based on Rhizome Discoloration Index (RDI). The result of this research showed that induced banana seedlings had higher plant resistance to Fusarium wilt than control. Asam salisilat (SA) merupakan signal penting dalam ketahanan tanaman, digunakan sebagaisenyawa pengimbas ketahanan tanaman pisang terhadap penyakit layu Fusarium. Pengimbasan dilakukan pada kelompok tunas kultur jaringan pisang dalam medium kultur jaringan MS cair dengan konsentrasi SA 0 ppm (sebagai kontrol), ⅛ LC50, ¼ LC50,½LC50 danLC50.Tunas yang bertahan hidup ditumbuhkan sebagai bibit dan uji ketahanan dilakukan dirumah kaca dengan inokulasiFusariumoxysporumf.sp. cubense (Foc) pada bibit pisang umur enambulan pasca aklimatisasi. Pengamatan dilakukan terhadap gejala layu pada daun (Leaf Symptom Index = LSI) dan diskolorasi pada bonggol (Rhizome Discoloration Index=RDI). Hasil penelitianmenunjukkan bahwa bibit pisang hasil pengimbasanmemiliki ketahanan yang lebih tinggi dibandingkan dengan perlakuan kontrol.

Hubungan Antara Aktivitas Poligalakturonase Dengan Virulensi RAS 4 Fusarium oxysporum f.sp. cubense

One of the major constraints of banana plantation in Indonesia is the occurrence of fusarium wilt disease caused by Fusarium oxysporum f.sp. cubense. The pathogen produced series of cell wall degradation extracellular enzymes which have important roles in pathogenicity. Many studies have been conducted to know the role of degrading enzyme banana pectin is the major component of cell wall. Many pectinolytic enzymes such as polygalacturonase and others have been isolated from many fungal plant pathogens. The study was aimed to know the role of polygalacturonase towards the virulence of race 4 of F. oxysporum f.sp. cubense. The result showed that from 10 isolates of race 4 of F. oxysporum f.sp. cubense, the most virulent isolate was Lmp1 followed by Srg1, Bgl6, Mln1, Bgl3, A13, Bnt2, Gnk3, Kjg1 dan Wsb5. This was indicated by high and low percentage of wilting leaves of banana cultivar Cavendish when they were inoculated with these isolates. Incubation period varied from 3 to 6 weeks after inoculation SDS-PAGE showed that polygalacturonase, mostly PG1 and PG2, was secreted by these isolates, whereas PG3 was only found in growing cultures of Gnk3 and Wsb5 isolates. Detection of polygalacturonase activity with diffusion agar and reducing sugar methods showed that the activity of polygalacturonase secreted by F. oxysporum f.sp. cubense in the growing culture had no correlation with the virulence of the fungal pathogen. Salah satu kendala utama dalam budidaya pisang di Indonesia adalah gangguan penyakit layu fusarium yang disebabkan oleh jamur Fusarium oxysporum f.sp. cubense. Jamur patogen ini menghasilkan serangkaian enzim ekstraselular pendegradasi dinding sel yang berperan dalam patogenesis. Beberapa penelitian telah dilakukan untuk mengetahui peran enzim yang mendegradasi pektin, yang merupakan komponen penting dinding sel tanaman. Beberapa enzim pektinolitik seperti poligalakturonase dan yang lainnya telah berhasil diisolasi dari berbagai spesies jamur penyebab penyakit tanaman. Penelitian ini bertujuan untuk mengetahui peranan poligalakturonase terhadap virulensi ras 4 F. oxysporum f.sp. cubense. Hasil penelitian menunjukkan bahwa dari 10 isolat F. oxysporum f.sp. cubense, yang mempunyai virulensi tertinggi hingga yang terendah berturut-turut adalah Lmp1, Srg1, Bgl6, Mln1, Bgl3, A13, Bnt2, Gnk3, Kjg1 dan Wsb5. Hal ini ditunjukkan dengan tinggi-rendahnya nilai persentase daun layu yang ditimbulkan oleh isolat-isolat tersebut pada bibit pisang kultivar Cavendish. Masa inkubasi bervariasi dari 3 hingga 6 minggu setelah inokulasi. Uji SDS-PAGE menunjukkan bahwa pada filtrat pertumbuhan isolat jamur-jamur patogen ini disekresikan poligalakturonase (PG) terutama PG1 dan PG2, sedangkan PG3 hanya dijumpai pada filtrat pertumbuhan isolat Gnk3 dan Wsb5. Adapun hasil deteksi aktivitas poligalakturonase dengan metode difusi agar serta gula reduksi menunjukkan bahwa aktivitas poligalakturonase yang disekresikan oleh F. oxysporum f.sp. cubense di dalam filtrat pertumbuhannya tidak berhubungan dengan virulensi jamur patogen tersebut.

PENGENDALIAN PENYAKIT LAYU PISANG DENGAN FUSARIUM NONPATOGENIK DAN FLUORESCENT PSEUDOMONADS

The study was aimed to know the ability of fluorescent pseudomonads and nonpathogenic Fusarium for controlling fusarium wilt of banan. The research was conducted both in the laboratory and glass ouse in the Faculty of Agriculture Gadjah Mada University. Laboratorial trial incuded the examining of antagonistic capacity in vitro and the population of these two antagonistic microorganism in compost medium. The examination of the effect of these two microorganisms in compost medium against fusarium wilt of banana Ambon Kuning cultivar was conducted in a glass house. The result showed that there was no antagonistic mechanism occured between fluorescent pseudomonads and nonpathogenic Fusarium. The treatment of compost with fluorescent pseudomonads or/and nonpathogenic Fusarium showed that there were differences on the optimum population of these two antagonistic microorganisms. Fluorescent pseudomonads attained its optimum population one week after inoculation while nonpathogenic Fusarium attained its optimum population two weeks after inoculation. The glass house trial showed taht compost enriched with two microorganisms with one week inocubation time reduced percentage of wilted leaves, although it was nonsignificant with control treatment. Field experiment should be conducted with higher population density of antagonist microorganisms.

Identifikasi Jamur Genus Aspergillus pada Gaplek di Kabupaten Gunung Kidul

The study was carried out in Gunung Kidul Regency of Yogyakarta special. Dried cassava was taken from the district of Nglipar (north zone), Wonosari (center zone), Semanu and Rongkop (south zones) for identification of the genera of Aspergillus growing on the samples. Clasification of the zones was based on the degree of rainfall on the area. Dichloran 18% Glyserol Agar (DG-18) medium was used for isolating pathogen, while Czapek Yeast Extract Agar (CYA), Czapek Yeast Extract Agar with 20% sucrose (CYA 20S) and Malt Extract Agar (MEA) media were used for identification. The fungi were identified on the basis of both macroscopic and microscopic morphologies. The result showed that The Genera Of Aspergillus growing on dry cassava were A. flavus, A. niger, A. oryzae, A. foetidus, A. zonatus and A. tamarii. A. flavus was a predominant fungus that grow on dry cassava.

Identifikasi Ras Fisiologis Fusarium oxysporum f.sp. cubense Berdasarkan Sifat Kompatibel Secara Vegetatif dan Pembentukan Bahan Volatil

Race characterization of F. oxysporum Schlecht. f.sp. cubense (E.F. Smith) Snyd. & Hans. by determining disease reaction is difficult because the result may be biased due to the variability of growing condition. This study is aimed to identify physiological races of F. oxysporum f.sp. cubense in banana plantation in the province of Daerah Istimewa Yogyakarta by examining the relation of the fungal pathogen isolates. The identification of physiological races of F. oxysporum f.sp. cubense was based on vegetative compatibility groups (VCGs). The research was conducted in The Laboratory of Mycology Faculty of Agriculture GMU on March to November 2000. Observation of heterokarion formed by the mutant of F. oxysporum f.sp. cubense on selective medium was carried out in order to identify the compatibility of two different fungal isolates. Nitrate non utilizing (nit) mutants obtained without mutagen were used as the label. Nit mutant obtained from the same wild type isolates could form heterokarion on minimal agar medium containing NaNO 3 as nitrogen source. Eleven isolates of F. oxysporum f.sp. cubense have been isolated from several cultivars of banana. Vegetative compatibility tests showed that of 11 eleven isolates, there were six different group VCGs where four of them formed volatile compound in rice medium whereas two of them did not. Key words: Fusarium wilt, F. oxysporum f.sp. cubense , vegetative compatibility groups (VCGs)

Ketahanan Beberapa Jamur Patogen terhadap Fungisida

Chemical control of plant pathogens have been done for a long time using contact and systemic fungicides. Resistance of the pathogens to fungicides may caused failure of disease control program. Studies by in vitro , in green house and fields were done at Yogyakarta to know the fungal which were resistant to several fungicides after treatment. The pathogen tested to fungicides were Colletotrichum capsici on red pepper to propineb, mancozeb, mixture of carbendazim and mancozeb, and thiophanate methyl, Alternaria porri on garlic to thiophanate methyl, Phytophthora palmivora on cocoa to Al-fosetyl, metalaxyl, mancozeb, and Copper Oxychloride, and Peronosclerospora maydis on corn to metalaxyl. The study indicated that C. capsici was resistant to propineb, mancozeb, and mixture of carbendazim and mancozeb, but sensitive to thiophanate methyl. A. porri from plant treated with thiophanate methyl indicated resistant to the fungicides. ED50 of Al-fosetyl and metalaxyl on P. palmivora were higher than on mancozeb and copper oxychloride, so that it was resistance strain. Key words: contact fungicides, systemic fungicides, resistance