Resistance of Three Superior New Banana Varieties on Several Vegetative Compatibility Groups Fusarium oxysporum f. sp. cubense

Balai Penelitian Tanaman Buah (Balitbu) Tropika telah melepas tiga varietas unggul baru (VUB) pisang dengan keunggulan masing-masing. Dalam menunjang keberhasilan pengembangan varietas unggul baru tersebut perlu diketahui informasi tentang ketahanannya terhadap beberapa Vegetative Compatibility Groups (VCGs) Fusarium oxysporum f. sp. cubense (Foc). Tujuan penelitian ini ialah menentukan ketahanan tiga VUB pisang terhadap beberapa VCGs Foc di rumah kasa. Penelitian dilakukan di laboratorium proteksi tumbuhan dan rumah kasa Balitbu Tropika di Solok, dari bulan September 2016 sampai bulan Desember 2017. Rancangan yang digunakan ialah acak kelompok 21 perlakuan dan 3 ulangan, masing-masing perlakuan terdiri atas 10 tanaman. Sebanyak 3 VUB pisang (Ketan 01, Kepok Tanjung dan Raja Kinalun) masing-masing diinokulasi dengan 7 VCGs Foc: yaitu VCG 0120/15, 0123, 0124/5, 0126, 01218, 01213/16 dan 01219. Hasil penelitian menunjukkan bahwa tiga VUB pisang menunjukkan respons ketahanan yang bervariasi terhadap isolat Foc dari berbagai VCGs dalam ras 1 dan ras 4. Ketahanan dipengaruhi oleh kompatibilitas masing-masing VCGs dari isolat Foc dengan varietas pisang. Varietas Ketan 01 (AA) mempunyai respons agak tahan dan tahan terhadap semua VCGs Foc yang diuji kecuali dengan VCG 0124/5 (ras 1) dan VCG 01213/16 (ras 4 tropis). Kepok Tanjung (ABB/BBB) rentan dan sangat rentan terhadap semua VCGs Foc, Raja Kinalun (ABB) memberikan respons tahan dan sangat tahan terhadap semua isolat VCGs Foc kecuali dengan isolat Foc VCG 0124/5 (ras 1) responsnya sangat rentan. Hasil penelitian ini bermanfaat sebagai informasi awal pengembangan varietas unggul baru pisang di Indonesia.

Molecular characterization and vegetative compatibility groups of Fusarium spp. pathogenic to Ilex paraguariensis A. St.-Hil.

Nas regiões Centro-Oeste e Sul do Brasil, a cultura da erva-mate (Ilex paraguariensis) constitui-se uma importante fonte de extrativismo florestal, além de diversificar a renda, principalmente na agricultura familiar. A erva-mate, como outras espécies florestais, é infectada por diversos patógenos, como o gênero Fusarium, causador da podridão-de-raízes. Os patógenos possuem ampla variabilidade genética, mesmo dentro de um único gênero e dentro de uma única espécie, resultado de adaptações ao meio em que vivem. Este estudo teve como objetivo avaliar o sequenciamento das regiões do genoma ITS e β-tubulina na identificação em nível de espécie dos isolados de Fusarium spp. patogênicos à erva-mate, e identificar a formação de grupos de compatibilidade vegetativa (VCG) entre os isolados de Fusarium spp. patogênicos à erva-mate. O sequenciamento das regiões ITS e β-tubulina consolidou a separação entre os sete isolados patogênicos em F. solani e F. oxysporum. Para esses isolados, a técnica para obtenção de mutantes nit foi adequada para a classificação fenotípica, fundamentais nos testes de VCG para espécies de Fusarium, sendo obtidos cinco VCG.

Genetic variability and vegetative compatibility in Aspergillus niger isolated from various food substances in Benin City Nigeria

In this investigation, Aspergillus niger isolated from eight food substances, have been classified based on the absence of heterokaryon formation. The size of their sporangia were differentiated, the wild and mutant strains were subjected to vegetative compatibility tests in order to group them into different vegetative compatibility groups (VCGs) which include VCG-1, VCG-2, VCG-3 and VCG-4. The strains were further tested for the possible formation of a stable heterokaryon using nit mutants generated on potato dextrose agar (PDA) containing 2.5% chlorate (KClO3), represented as PDC. Based on the vegetative compatibility groups, nit mutants were paired on a minimal medium (MM) for complementation test. Interestingly, there was compatibility with mycelia showing anastomoses but without the formation of heterokaryon. The vegetative compatibility groups suggested four genotypes and polymorphism in the het loci. A population study for detailed genotyping is suggested in order to unravel the genetic recombination in A. niger.

Draft Genome Sequences of 20 Aspergillus flavus Isolates from Corn Kernels and Cornfield Soils in Louisiana

ABSTRACT Aspergillus flavus is a common saprophyte and opportunistic fungal pathogen that infects plants, animals, and humans. It also produces numerous toxic and nontoxic secondary metabolites. Here, we report the draft genome sequences of 20 A. flavus isolates, belonging to 16 vegetative compatibility groups, from Louisiana corn kernels and cornfield soils.

Phylogenetic Analysis, Vegetative Compatibility, Virulence, and Fungal Filtrates of Leaf Curl Pathogen Colletotrichum fioriniae From Celery

Leaf curl of celery, caused by Colletotrichum acutatum sensu lato, has been reported in the U.S. A multi-locus phylogenetic analysis with three genes was conducted with a collection of isolates from celery (23) and non-celery (29) hosts to evaluate their taxonomic position within C. acutatum sensu lato. The three DNA regions used for phylogenetic analysis included the introns of glutamine synthase (GS) and glyceraldehyde-3-phosphate dehydrogenase (GPDH), and the partial sequence of the histone3 (his3) gene. Moreover, celery and non-celery isolates were evaluated for vegetative compatibility and pathogenicity on celery. Culture filtrates from celery and non-celery isolates were also evaluated for their ability to reproduce leaf curl symptoms. A total of 23 celery isolates were evaluated based on phylogenetic analysis, which showed that all celery isolates were closely related and belonged to the newly described species C. fioriniae. The celery isolates were grouped into six vegetative compatibility groups indicating the population was not clonal. Twenty two of 23 isolates of C. fioriniae from celery and other hosts (26 of 29) caused leaf curl symptoms. Isolates of C. acutatum, C. nymphaeae, and C. godetiae were pathogenic but did not cause leaf curl symptoms. Isolates of C. lupini, C. johnstonii, and C. gloeosporioides were not pathogenic on celery. In addition, cell-free fungal culture filtrates caused leaf curl symptoms on celery indicating that certain isolates produce a metabolite that can cause leaf curl symptoms on celery, possibly indole acetic acid (IAA).

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.