Virulence not linked with vegetative compatibility groups in Australian cotton Verticillium dahliae isolates

Verticillium dahliae, the causal agent of Verticillium wilt, is a soil-borne ascomycete that infects numerous agriculturally important crops globally, including cotton. As a billion-dollar industry, cotton is economically important to Australia and the management of disease such as Verticillium wilt is key for the success of the industry. Internationally, defoliating V. dahliae isolates belonging to Vegetative Compatibility Group (VCG) 1A cause severe damage to cotton, while non-defoliating VCG2A isolates result in significantly less disease. However, in Australia, VCG2A is causing more severe damage to crops in the field than the defoliating VCG1A. This study aimed to replicate field observations in controlled greenhouse conditions. We examined and compared disease symptoms on a range of Australian commercial cotton varieties when inoculated with different V. dahliae VCGs. Seedlings were root dipped in conidial suspensions and assessed over seven weeks. The final disease score, disease over time and root length were analysed. Plant mortality resulted from both V. dahliae VCG1A and VCG2A isolates across all cotton varieties used, confirming that there are virulent VCG2A isolates present in Australia. To our knowledge, although virulent on other plant hosts, V. dahliae VCG2A has not previously been reported to be highly virulent in cotton. We infer that virulence cannot be defined solely by VCG in Australian V. dahliae isolates causing disease in cotton.

High-Quality Draft Genome Sequence of the Causal Agent of the Current Panama Disease Epidemic

We present a high-quality draft genome assembly for Fusarium oxysporum f. sp. cubense tropical race 4 (Fusarium odoratissimum), assembled from PacBio reads and consisting of 15 contigs with a total assembly size of 48.59 Mb. This strain appears to belong to vegetative compatibility group complex 01213/16.

Evaluation of Some Specific Primer Sets Development for Detecting Fusarium oxysporum f. sp. cubense Tropic Race 4 (Foc TR4) Originating from Indonesia

Fusarium oxysporum f. sp. cubense tropic race 4 (Foc TR4) strain which belong to Vegetative Compatibility Group (VCG) 01213 is the most devastating disease in global banana production. Validation of specific primer sets using the positive control (Foc TR4). In total, 50 isolates of Foc are collected from several banana production regions in Indonesia represent the group of VCG, races, genotype, cultivars, which are confirmed as Foc based on the tested using FocEf3 primer set, except Cjr-2 and Lmp-4 isolates. Foc-1/Foc-2 could amplify 34 Foc isolates included in Foc race 4. Three specific primer sets i.e. TR4-F/TR4-R, Six-1c, and TR4-F2/TR4-R1 are used to classify Foc isolates into Foc tropic race 4. TR4-F/TR4-R is known have the highest specificity as it could amplify 35 Foc isolates including positive controls (Foc TR4) compared to the other primer sets (Six-1c and TR4-F2/TR4-R1). This research indicates that there are a large number of diversity strains found in Foc isolates to be studied for further research. Race 4 of Foc (STR4 or TR4) is known to be widespread in several regions in Indonesia. Therefore, specific primer set development needs to be done to detect Foc TR4 and the most damaging strains on Foc TR4 based on molecular data.IntisariFusarium oxysporum f. sp. cubense ras 4 tropika (Foc TR4) yang termasuk ke dalam kelompok VCG 01213 merupakan patogen yang paling merusak dalam produksi tanaman pisang secara global. Validasi primer spesifik berbasis PCR menggunakan kontrol positif (Foc TR4). Total, 50 isolat Foc dikoleksi dari beberapa daerah produksi pisang di Indonesia mewakili VCG, ras, genotipe dan kultivar yang dikonfirmasi sebagai isolat Foc berdasarkan pengujian menggunakan primer FocEf3, kecuali isolat Cjr-2 dan Lmp-4. Foc-1/Foc-2 dapat mengamplifikasi 34 isolat Foc yang termasuk ke dalam Foc ras 4. Selanjutnya tiga pasang primer spesifik yaitu TR4-F/TR4-R, Six-1c, dan TR4-F2/TR4-R1 digunakan untuk mengelompokkan isolat-isolat tersebut ke dalam isolat Foc ras 4 tropika. TR4-F/TR4-R diketahui memiliki spesifitas tertinggi karena dapat mengamplifikasi sebanyak 35 isolat Foc termasuk kontrol positif (Foc TR4) dibandingkan dengan primer lainnya (Six-1c dan TR4-F2/TR4-R1). Penelitian ini menunjukkan bahwa terdapat sejumlah besar keragaman strain yang terlihat pada isolat-isolat Foc tersebut untuk dapat dipelajari lebih lanjut. Ras 4 dari Foc (STR4 atau TR4) diketahui tersebar luas pada beberapa daerah di Indonesia. Oleh karena itu, perlu dilakukan pengembangan primer spesifik untuk mendeteksi Foc TR4 dan strain yang paling merusak pada Foc TR4 berdasarkan data molekuler.

Kompatibilitas Vegetatif Fusarium oxysporum dari Beberapa Tanaman Inang

ABSTRACTVegetatif compatibility of Fusarium oxysporum on various hostsMany strains or race of Fusarium oxysporum can be grouped based on compatibility reproduction from a variety of different strains called Vegetative Compatibility Group (VCG). This study was aimed to determine how the grouping of several isolates of F. oxysporum and grouping of several hosts of the fungus by vegetative compatibility group. Fusarium oxysporum isolated from chickpea plants that showed symptoms of fusarium wilt. The isolates of F. oxysporum of chili and tomatoes obtained from the culture collections of Mycology Laboratory of IPB. Stages of vegetative compatibility testing assayed through recovery of nit mutants, the identification of phenotype of nit mutant, and complementation test. There are 29 mutants isolated from the isolates of F. oxysporum. Nit1 mutant was obtained from all isolates of beans, tomatoes and peppers. NitM and Nit3 mutant isolates were obtained from chickpea 4 and chili sequentially. Two VCG and one single self compatibility (SSC) were assayed from isolates of F. oxysporum based on complementation testing.Keywords: Beans, Fusarium wilt, Nit mutant, SSC, VCGABSTRAKJamur Fusarium oxysporum memiliki banyak forma spesialis dan ras. Jamur ini dapat dikelompokkan berdasarkan kompatibilitas reproduksi dari berbagai strain yang berbeda disebut dengan vegetative compatibility group (VCG). Penelitian ini bertujuan untuk mengetahui cara pengelompokkan F. oxysporum dan pengelompokkan jamur tersebut dari beberapa inang berdasarkan kelompok kompatibilitas vegetatifnya. Isolasi F. oxysporum dilakukan dari tanaman kacang panjang yang menunjukkan gejala layu fusarium. Isolat F. oxysporum dari cabai dan tomat berasal dari koleksi Laboratorium Mikologi IPB. Tahapan pengujian kompatibilitas vegetatif melalui pembiakan nit mutan, identifikasi fenotipe nit mutan, dan pengujian komplementasi. Isolasi mutan F. oxysporum didapatkan 29 mutan. Mutan nit1 didapatkan dari semua isolat yang diperoleh dari semua inang yang berbeda yaitu kacang panjang, tomat dan cabai. Mutan nitM hanya didapatkan dari isolat kacang panjang 4 dan mutan nit3 hanya didapatkan dari isolat cabai. Berdasarkan uji komplementasi F. oxysporum yang diuji terdiri dari dua VCG dan satu single self compatibility (SSC).Kata Kunci: Kacang panjang, Layu fusarium, Nit mutant, SSC, VCG

Uji Virulensi Isolat Fusarium oxysporum f.sp. cubense Dalam Vegetative Compatibility Group Complex 0124 Pada Tanaman Pisang

<p>Patogen Fusarium oxysporum f.sp. cubense (Foc) ras 1 dilaporkan tidak patogenik terhadap pisang kelompok Cavendish, namun beberapa hasil penelitian menunjukkan bahwa ras 1 pada kondisi tertentu juga dapat menyerang pisang kelompok Cavendish. Sedikit laporan tentang variasi virulensi Foc ras 1 dalam VCG complex 0124 terhadap pisang Ambon Kuning (AAA/Gros Michel) dan Ambon Hijau (AAA/Cav.subgroup). Tujuan penelitian ialah mengetahui variasi virulensi isolat Foc dalam VCG complex 0124 terhadap pisang Ambon Kuning dan Ambon Hijau. Penelitian dilakukan di Laboratorium Proteksi dan Rumah Kasa Balai Penelitian Tanaman Buah Tropika Solok, dari Bulan April sampai Oktober 2011. Rancangan yang digunakan ialah acak kelompok faktorial dengan tiga ulangan setiap perlakuan terdiri atas 10 tanaman. Faktor pertama ialah lima isolat Foc dalam VCG complex 0124: F1=0124/5 (WJP 02), F2=0124/5/8 (WJG 03), F3=0124/5/8 (WJG 09), F4=0124/5 (Indo 119), dan F5=0124/5/20 (02020114B) dan faktor kedua ialah dua varietas pisang yaitu: V1= varietas Ambon Hijau (AAA/Cav.subgroup) dan V2=varietas Ambon Kuning (AAA/Gros Michel). Hasil penelitian menunjukkan bahwa semua isolat Foc dalam VCG complex 0124 yang diuji dapat menyerang pisang Ambon Kuning dan Ambon Hijau dengan persentase serangan yang sangat tinggi yaitu 96,67–98,33%. Perlakuan tunggal jenis isolat terhadap peubah masa inkubasi menunjukkan bahwa isolat 0124/5/8 (WJG 03) masa inkubasinya paling panjang yaitu 26,57 hari dan berbeda nyata dengan isolat lainnya. Masa inkubasi penyakit oleh semua isolat yang diuji pada Ambon Kuning lebih panjang (24,27 hari) dan berbeda nyata dengan Ambon Hijau (16,42 hari). Semua isolat Foc yang diuji sangat virulen pada pisang Ambon Kuning (AAA/Gros Michel) dan Ambon Hijau (AAA/Cav.subgroup) dengan indeks keparahan penyakit pada daun dan bonggol berkisar antara 4,72–5,22 dan 5,03–5,14. Hasil penelitian ini mendorong kajian lebih lanjut tentang biologi dan virulensi patogen dalam rangka memperoleh teknik pengendalian yang tepat.</p>

Genetic Analysis of the Aspergillus flavus Vegetative Compatibility Group to Which a Biological Control Agent That Limits Aflatoxin Contamination in U.S. Crops Belongs

ABSTRACTSome filamentous fungi inAspergillussectionFlaviproduce carcinogenic secondary compounds called aflatoxins. Aflatoxin contamination is routinely managed in commercial agriculture with strains ofAspergillus flavusthat do not produce aflatoxins. These non-aflatoxin-producing strains competitively exclude aflatoxin producers and reshape fungal communities so that strains with the aflatoxin-producing phenotype are less frequent. This study evaluated the genetic variation within naturally occurring atoxigenicA. flavusstrains from the endemic vegetative compatibility group (VCG) YV36. AF36 is a strain of VCG YV36 and was the first fungus used in agriculture for aflatoxin management. Genetic analyses based on mating-type loci, 21 microsatellite loci, and a single nucleotide polymorphism (SNP) in theaflCgene were applied to a set of 237 YV36 isolates collected from 1990 through 2005 from desert legumes and untreated fields and from fields previously treated with AF36 across the southern United States. One haplotype dominated across time and space. No recombination with strains belonging to VCGs other than YV36 was detected. All YV36 isolates carried the SNP inaflCthat prevents aflatoxin biosynthesis and themat1-2idiomorph at the mating-type locus. These results suggest that VCG YV36 has a clonal population structure maintained across both time and space. These results demonstrate the genetic stability of atoxigenic strains belonging to a broadly distributed endemic VCG in both untreated populations and populations where the short-term frequency of VCG YV36 has increased due to applications of a strain used to competitively exclude aflatoxin producers. This work supports the hypothesis that strains of this VCG are not involved in routine genetic exchange with aflatoxin-producing strains.

Evaluation of the Atoxigenic Aspergillus flavus Strain AF36 in Pistachio Orchards

The atoxigenic strain Aspergillus flavus AF36, which has been extensively used as a biocontrol agent in commercial corn and cotton fields to reduce aflatoxin contamination, was applied in research pistachio orchards from 2002 to 2005 and in commercial pistachio orchards from 2008 to 2011. AF36 was applied as hyphae-colonized steam-sterilized wheat seed (the same product and same application rate as used in cotton fields). In all orchards, applying the wheat-AF36 product substantially increased the proportion of vegetative compatibility group (VCG) YV36, the VCG to which AF36 belongs, within A. flavus soil communities. Application of the AF36 product in additional years further increased YV36 in the soil until it composed 93% of the A. flavus isolates in treated commercial orchards. Nonetheless, application of the AF36 product did not result in increased incidence of kernel decay of the nuts. For nuts harvested from commercial orchards, reductions in percentages of samples contaminated with aflatoxin from treated orchards (relative to that for untreated orchards) ranged from 20 to 45%, depending on the year. Because of the high value of pistachio nuts and the costs associated with rejection of shipments due to aflatoxin contamination, these reductions are significant and valuable to the pistachio industry.

Penyakit Layu Fusarium Pada Tanaman Pisang di Provinsi NAD: Sebaran dan Identifikasi Isolat Berdasarkan Analisis Vegetative Compatibility Group

ABSTRAK. Penyakit layu yang disebabkan oleh cendawan Fusarium oxysporum f. sp. cubense (Foc) merupakan penyakit paling berbahaya pada tanaman pisang. Untuk mendapatkan teknik pengendalian yang tepat, maka informasi tentang distribusi dan karakter biologi patogen tersebut perlu diketahui. Penelitian ini bertujuan mengetahui distribusi penyakit layu Fusarium di Provinsi Nanggroe Aceh Darussalam (NAD) dan varietas pisang yang diserangnya serta mengidentifikasi isolat Foc berdasarkan analisis vegetative compatibility group (VCG). Survei dan pengumpulan sampel tanaman pisang terserang penyakit dilakukan pada bulan Januari 2007 dan Juli 2008. Isolasi dan pemurnian isolat dilakukan di Laboratorium Hama dan Penyakit Tanaman, Balai Penelitian Tanaman Buah (Balitbu) Tropika Solok pada bulan Februari 2007 dan Agustus 2008. Analisis VCG dilakukan di Departement of Primary Industry, Plant Pathology Section, Indooroopilli Australia dan Laboratorium Hama dan Penyakit Tanaman Balai Penelitian Tanaman Buah Tropika sejak bulan Juli 2007 sampai bulan Juli 2009. Tester VCG berjumlah 17 nomor yang berasal dari Department of Primary Industry, Plant Pathology Section, Indooroopilli Australia. Hasil penelitian menunjukkan bahwa penyakit layu Fusarium ditemukan di semua lokasi pengamatan di Provinsi NAD pada empat varietas pisang, yaitu Barangan (AAA), Raja (AAB), Kepok (ABB/BBB), dan Siem (ABB). Dari 50 isolat Foc yang dikoleksi terkelompok ke dalam dua VCG, 37 isolat (74%) termasuk dalam VCG 01213/16 (Tropical Race 4), ditemukan pada tiga varietas (Barangan, Kepok, dan Raja), sembilan isolat masuk VCG 01218 (Ras 1) ditemukan hanya pada varietas Siem, sedangkan VCG empat isolat yang menyerang pisang varietas Siem belum ditemukan. Foc VCGs 01213/16 (TR4) paling dominan ditemukan di Provinsi NAD, baik dari jumlah, sebaran lokasi, maupun ragam varietas yang diserangnya. Data ini menginformasikan bahwa pengembangan tanaman pisang di Provinsi NAD harus dilakukan secara selektif serta mempertimbangkan langkah-langkah preventif dan pengendalian yang tepat.<br /><br />ABSTRACT. Jumjunidang, Edison, Riska, and Hermanto, C 2012. Fusarium Wilt Disease on Banana in NAD Province: Distribution and Identification of Isolates through Vegetative Compatibility Group Analysis. Wilt disease caused by Fusarium oxysporum f. sp. cubense (Foc) is the most dangerous pathogen on banana. Knowledge of the distribution and biological characters of the pathogen is very important to arrange an effective control technique. The objectives of this study were to reveal distribution of Fusarium wilt disease in Nanggroe Aceh Darussalam (NAD) Province and infected banana varieties as well as to identify of Foc isolates with vegetative compatibility group (VCG) analysis Survey and collection of samples of infected banana plants in NAD Province were carried out in January 2007 and July 2008. Isolation and purification of the isolates with single spore techniques were done at Plant Protection Laboratory of Indonesian Tropical Fruit Research Institute (ITFRI), Solok in February 2007 and August 2008. Vegetative compatibility group analysis was performed at Department of Primary Industry, Plant Pathology Section, Indooroopilli Australia and Plant Protection Laboratory of ITFRI from July 2007 to July 2009. Seventeen VCG testers were originated from Department of Primary Industry, Plant Pathology Section, Indooroopilli Australia. The results showed that Fusarium wilt disease was found in all surveyed locations in NAD Province on four banana varieties, i.e. Barangan (AAA), Raja (AAB), Kepok (ABB/BBB), and Siem (ABB). Fifty isolates of the pathogen Foc have been collected and grouped into two VCGs, 37 isolates (74%) were grouped into VCG 01213/16 (Tropical Race 4) attacking three varieties (Barangan, Kepok, and Raja), nine isolates were clustered into VCG 01218 (Race 1) attacking Siem variety only, and the other four isolates from Siem variety had not been identified yet. Foc VCG 01213/16 (TR4) was very dominant in NAD Province, in terms of numbers, location, and distribution of attacked varieties. These findings inform that the development of banana plants in the NAD province should be done selectively and consider both preventive measures and appropriate controls.<br />