Uji Ketahanan Lima Varietas Tanaman Cabai Merah (Capsicum annuum) terhadap Penyakit Tular Tanah (Fusarium oxysporum f.sp capsici)

Produksi tanaman cabai merah di Indonesia dipengaruhi oleh penyakit yang menyerang tanaman cabai merah yang disebabkan oleh cendawan Fusarium oxysporum f.sp capsici dan varietas tanaman cabai merah. Pemilihan varietas yang unggul meliputi Reskin, Gada, Imperial10, Osaka03, dan Maruti dilakukan untuk mendapatkan varietas yang tahan terhadap serangan Fusarium oxysporum f.sp capsici. Penelitian ini bertujuan untuk menguji ketahanan lima varietas tanaman cabai merah terhadap tingkat toleransi penyakit Fusarium oxysporum, untuk mendeskripsikan pengaruh dosis Fusarium oxysporum terhadap tingkat toleransi lima varietas tanaman cabai merah dan untuk mendeskripsikan pengaruh kombinasi varietas dan dosis Fusarium oxysporum terhadap tingkat toleransi tanaman cabai merah. Rancangan penelitian ini adalah rancangan acak kelompok (RAK) dengan tiga kali pengulangan. Tanaman cabai merah berumur 14 HST diinfeksi oleh cendawan Fusarium oxysporum dengan dosis 0 g, 10 g, dan 20 g selama 75 HST. Pengamatan dilakukan dengan  memberikan kategori penilaian terhadap ketahanan tanaman dari serangan cendawan, tinggi tanaman 45 HST, dan hasil produksi 75 HST. Data tinggi tanaman dan hasil produksi yang diperoleh dianalisis dengan ANAVA dua arah dan bila terdapat perbedaan yang signifikan maka dilanjutkan uji Duncan. Data tingkat ketahanan tanaman terhadap serangan Fusarium oxysporum dianalisis menggunakan analisis deskriptif. Hasil penelitian menunjukkan bahwa lima varietas tanaman cabai merah memengaruhi tingkat toleransi. Varietas Gada berkriteria tahan, varietas Imperial 10, varietas Osaka03, dan varietas Reskin berkriteria agak tahan, sedangkan varietas Maruti berkriteria rentan. Tidak ada pengaruh dosis Fusarium oxysporum terhadap tingkat toleransi dan tidak ada perbedaan kombinasi varietas dan dosis Fusarium oxysporum terhadap tingkat toleransi   Kata kunci: varietas tanaman Cabai merah; Fusarium oxysporum f.sp capsici; kriteria ketahana

Basal rot of narcissus : understanding pathogenicity in fusarium oxysporum f. sp. narcissi

Fusarium oxysporum is a globally distributed soilborne fungal pathogen causing root rots, bulb rots, crown rots and vascular wilts on a range of horticultural plants. Pathogenic F. oxysporum isolates are highly host specific and are classified as formae speciales. Narcissus is an important ornamental crop and both the quality and yield of flowers and bulbs can be severely affected by a basal rot caused by F. oxysporum f. sp. narcissi (FON); 154 Fusarium isolates were obtained from different locations and Narcissus cultivars in the United Kingdom, representing a valuable resource. A subset of 30 F. oxysporum isolates were all found to be pathogenic and were therefore identified as FON. Molecular characterisation of isolates through sequencing of three housekeeping genes, suggested a monophyletic origin with little divergence. PCR detection of 14 Secreted in Xylem (SIX) genes, previously shown to be associated with pathogenicity in other F. oxysporum f. spp., revealed different complements of SIX7, SIX9, SIX10, SIX12 and SIX13 within FON isolates which may suggest a race structure. SIX gene sequences were unique to FON and SIX10 was present in all isolates, allowing for molecular identification of FON for the first time. The genome of a highly pathogenic isolate was sequenced and lineage specific (LS) regions identified which harboured putative effectors including the SIX genes. Real-time RT-PCR, showed that SIX genes and selected putative effectors were expressed in planta with many significantly upregulated during infection. This is the first study to characterise molecular variation in FON and provide an analysis of the FON genome. Identification of expressed genes potentially associated with virulence provides the basis for future functional studies and new targets for molecular diagnostics

Hyphal growth of phagocytosed fusarium oxysporum causes cell lysis and death of murine macrophages

Peer reviewedPublisher PD

A Detection Method for Tropical Race 4 of the Banana Pathogen Fusarium oxysporum f. sp. cubense

Fusarium oxysporum f. sp. cubense (Foc) is the causal agent of Fusarium wilt, the devastating disease that ruined the ‘Gros Michel’ (AAA)-based banana production in the first half of the 20th century. The occurrence of a new variant in Southeast Asia that overcomes the resistance in Cavendish clones such as ‘Grand Naine’ (AAA) is a major concern to current banana production worldwide. The threat posed by this new variant, called tropical race 4 (TR4), may be overcome by the introduction of resistant cultivars. However, the identification of new resistant sources or breeding for resistance is a long-term effort. Currently, the only option to control the disease is to avoid or reduce the spread of the pathogen by eradication of infected plants and isolation of infested plantations. This requires sensitive and highly specific diagnostics that enable early detection of the pathogen. A two-locus database of DNA sequences, from over 800 different isolates from multiple formae speciales of F. oxysporum, was used to develop a molecular diagnostic tool that specifically detects isolates from the vegetative compatibility group (VCG) 01213, which encompasses the Foc TR4 genotype. This diagnostic tool was able to detect all Foc TR4 isolates tested, while none of the Foc isolates from 19 VCGs other than 01213 showed any reaction. In addition, the developed diagnostic tool was able to detect Foc TR4 when using DNA samples from different tissues of ‘Grand Naine’ plants inoculated with TR4 isolate

Crossing Lilium Orientals of different ploidy creates Fusarium-resistant hybrid

Oriental hybrid lily is of great commercial value, but it is susceptible to Fusarium disease that causes a significant loss to the production. A diploid Oriental hybrid resistant to Fusarium, Cai-74, was diploidized from triploid obtained from the offspring of tetraploid (from ‘Star Fighter’) and diploid (‘Con Amore’, ‘Acapulco’) by screening the hybrids of different cross combinations following inoculating Fusarium oxysporum to the tissue cultured plantlets in a greenhouse. By analyzing saponins content in bulbs of a number of lily genotypes with a known Fusarium resistance, it was found that the mutant Cai-74 had a much higher content of saponin than its parents. Highly resistant wild _L. dauricum_ had the highest level (4.59mg/g), followed by the resistant Cai-74 with 4.01mg/g. The resistant OT cultivars ‘Conca d’or’ and ‘Robina’ had a higher saponins content (3.70 mg/g) and 2.83 mg/g, than the susceptible Oriental lily cultivars ‘Sorbonne’, ‘Siberia’ and ‘Tiber’. The hybrid Cai-74 had a different karyotype compared with the normal Lilium Oriental hybrid cultivars. The results suggested that Cai-74 carries a chromosomal variation correlated to Fusarium resistance. Cai-74 might be used as a genetic resource for breeding of Fusarium resistant cultivars of Oriental hybrid lilies

First record of Fusarium oxysporum F.SP. radicis-lycopersici in Malta

Disease note describing the first record of Fusarium oxysporum F.SP. radicis-lycopersici on tomatoes in Maltapeer-reviewe

Genetic mapping, synteny, and physical location of two loci for Fusarium oxysporum f. sp. tracheiphilum race 4 resistance in cowpea [Vignaunguiculata (L.) Walp].

Fusarium wilt is a vascular disease caused by the fungus Fusariumoxysporum f.sp. tracheiphilum (Fot) in cowpea [Vignaunguiculata (L.) Walp]. In this study, we mapped loci conferring resistance to Fot race 4 in three cowpea RIL populations: IT93K-503-1 × CB46, CB27 × 24-125B-1, and CB27 × IT82E-18/Big Buff. Two independent loci which confer resistance to Fot race 4 were identified, Fot4-1 and Fot4-2. Fot4-1 was identified in the IT93K-503-1 (resistant) × CB46 (susceptible) population and was positioned on the cowpea consensus genetic map, spanning 21.57-29.40 cM on linkage group 5. The Fot4-2 locus was validated by identifying it in both the CB27 (resistant) × 24-125B-1 (susceptible) and CB27 (resistant) × IT82E-18/Big Buff (susceptible) populations. Fot4-2 was positioned on the cowpea consensus genetic map on linkage group 3; the minimum distance spanned 71.52-71.75 cM whereas the maximum distance spanned 64.44-80.23 cM. These genomic locations of Fot4-1 and Fot4-2 on the cowpea consensus genetic map, relative to Fot3-1 which was previously identified as the locus conferring resistance to Fot race 3, established that all three loci were independent. The Fot4-1 and Fot4-2 syntenic loci were examined in Glycine max, where several disease-resistance candidate genes were identified for both loci. In addition, Fot4-1 and Fot4-2 were coarsely positioned on the cowpea physical map. Fot4-1 and Fot4-2 will contribute to molecular marker development for future use in marker-assisted selection, thereby expediting introgression of Fot race 4 resistance into future cowpea cultivars

Murine model for Fusarium oxysporum invasive fusariosis reveals organ-specific structures for dissemination and long-term persistence

Peer reviewedPublisher PD

A severe outbreak of crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici in Malta

A severe outbreak of crown and root rot of tomato was observed in greenhouses in Malta in eight locations during the period November 2004 – February 2005. Besides root and crown symptoms, several plants showed cankers at the basal part of the stem. Fusarium oxysporum was constantly isolated from these plants. One isolate from each location was tested for pathogenicity on tomato seedlings. All these isolates caused severe necrotic lesions of the crown and roots, and stem cankers. It was concluded that F. oxysporum f. sp. radicis-lycopersici (FORL) was the cause of the outbreak. Incidence ranged from 10 to 50%. Cold weather conditions occurring in Malta during the late fall and winter of 2004–2005 probably favoured the disease. The use of tomato cultivars or hybrids resistant to FORL is suggested for winter tomato crops in south Mediterranean areas.peer-reviewe

Generating Phenotypic Diversity in a Fungal Biocatalyst to Investigate Alcohol Stress Tolerance Encountered during Microbial Cellulosic Biofuel Production

peer-reviewedConsolidated bioprocessing (CBP) of lignocellulosic biomass offers an alternative route to renewable energy. The crop pathogen Fusarium oxysporum is a promising fungal biocatalyst because of its broad host range and innate ability to co-saccharify and ferment lignocellulose to bioethanol. A major challenge for cellulolytic CBP-enabling microbes is alcohol inhibition. This research tested the hypothesis that Agrobacterium tumefaciens - mediated transformation (ATMT) could be exploited as a tool to generate phenotypic diversity in F. oxysporum to investigate alcohol stress tolerance encountered during CBP. A random mutagenesis library of gene disruption transformants (n=1,563) was constructed and screened for alcohol tolerance in order to isolate alcohol sensitive or tolerant phenotypes. Following three rounds of screening, exposure of select transformants to 6% ethanol and 0.75% n-butanol resulted respectively in increased (≥11.74%) and decreased (≤43.01%) growth compared to the wild –type (WT). Principal component analysis (PCA) quantified the level of phenotypic diversity across the population of genetically transformed individuals and isolated candidate strains for analysis. Characterisation of one strain, Tr. 259, ascertained a reduced growth phenotype under alcohol stress relative to WT and indicated the disruption of a coding region homologous to a putative sugar transporter (FOXG_09625). Quantitative PCR (RT-PCR) showed FOXG_09625 was differentially expressed in Tr. 259 compared to WT during alcohol-induced stress (P<0.05). Phylogenetic analysis of putative sugar transporters suggests diverse functional roles in F. oxysporum and other filamentous fungi compared to yeast for which sugar transporters form part of a relatively conserved family. This study has confirmed the potential of ATMT coupled with a phenotypic screening program to select for genetic variation induced in response to alcohol stress. This research represents a first step in the investigation of alcohol tolerance in F. oxysporum and has resulted in the identification of several novel strains, which will be of benefit to future biofuel research.Funding provided through the Irish Department of Agriculture and Food's Research Stimulus Fund (Project Code RSF 07 513