The fungus Fusarium oxysporum f.sp. cubense (Focub) causes Fusarium wilt of banana. Focub strains are divided into races according to their host specificity, but which virulence factors underlie these interactions is currently unknown. In the F. oxysporum f.sp. lycopersici (Fol)-tomato system, small secreted fungal proteins, called Six proteins, were identified in the xylem sap of infected plants. The Fol Six1 protein contributes to virulence and has an avirulence function by activating the I-3 immune receptor of tomato. The Focub tropical race 4 (TR4) genome harbors three SIX1 homologs: SIX1a, b and c. In this study, the role of Focub-SIX1a in pathogenicity was evaluated since this homolog is present in not only TR4 but also in other races. A deletion mutant of the SIX1a gene from Focub TR4 strain II5 was generated (FocubΔSIX1a) and tested in planta. Mutants were found to be severely compromised in their virulence. Ectopic integration of the Focub-SIX1a gene in the FocubΔSIX1a strain restored virulence to wild type levels. We conclude that Focub-SIX1a is required for full virulence of Focub TR4 towards Cavendish banana.
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.
Background Brown spot disease is one of the most destructive foliar diseases of rice. Biological control of this disease is considered more environmentally safe, but the biological control agents have limited availability. The fungus Trichoderma can be used as a biocontrol agent for various plant diseases, including brown spots. Indigenous Trichoderma species from West Timor were evaluated in this study to reveal their effectiveness in reducing brown spot disease of upland rice. The study was conducted under a screen house condition using a factorial treatment design laid out in a completely randomized design. The two factors were the brown spot disease control method (T. viride, T. harzianum, T. hamatum, fungicide Trivia 73 WP, and a control treatment) and upland rice genotype (Inpago 7 and Breun Senaren 2). Results The results showed that Trichoderma spp. and the fungicide Trivia 73 WP caused significantly lower AUDPC and apparent infection rate than the control treatment. The total phenol content and agronomic characters (number of reproductive tillers per plant, number of filled grains per panicle, grain yield per plant) were higher in the Trichoderma and fungicide treatments than the control treatment. Meanwhile, tannin and saponin levels were non-significantly different among treatments. Trichoderma and the fungicide Trivia treatments effectively suppressed brown spot disease of upland rice, and the efficacy was dependent on the rice variety, with a mean efficacy range over the two varieties of 27.05–36.42%. The Trichoderma and the fungicide Trivia treatments increased the grain yield per plant differentially in the 2 rice varieties, with a mean grain yield increase over the 2 varieties of 13.0% (T. viride), 23.5% (T. harzianum), 35.0% (T. hamatum), and 19.9% (Trivia 73 WP). Conclusion Efficacy of local Trichoderma of West Timor and the fungicide Trivia treatments were varietal dependent with T. hamatum being the most effective in reducing the brown spot disease and producing the highest grain yield increase over the 2 rice varieties. The local Trichoderma species of West Timor have a future potential as biocontrol agents of upland rice brown spot disease, but it is necessary to further evaluate their effectiveness against the disease in replicated field trials.
Downy mildew is a serious threat to corn (maize) production in the tropics and subtropics. Corn is native to Central America, and was introduced into South-East Asia by the Spanish colonisers in the 1700s. Corn is evolutionarily naïve to downy mildews of the genus Peronosclerospora. Consequently, corn monocultures are particularly susceptible to a variety of Peronosclerospora species, which spread to the crop from local grasses. Globally, corn is one of the most important crops for both humans and livestock. Several downy mildews of corn have been identified as potential threats to global food security, and trade with corn seeds is strictly regulated to avoid spreading the pathogens. Despite their importance, little is known about the biodiversity of graminicolous downy mildews, because their identification has often relied on variable morphological features, such as conidial dimensions. DNA barcodes for most species have become available only recently. During surveys for downy mildews on corn in Indonesia, a previously unrecognised species of Peronosclerospora was found and investigated using a combination of morphological characters and molecular phylogenetic analyses. The new species, introduced here as Peronosclerospora neglecta, is widely distributed in South-East Asia from Thailand to eastern Indonesia. The impact of this downy mildew can be severe, with complete crop losses in heavily affected fields. Given the aggressiveness of the species, close surveillance is warranted to restrict its further spread.
Bananas are cultivated everywhere in Indonesia, including in the dryland areas of East Nusa Tenggara. In the province, diferrent banana cultivars are cultivated for different purposes. Well adapted the dry climate, Musa ABB Pisang Kepok is the most widely cultivated in the province, including in Sumba Island where it is known locally as Pisang Marmi. Unfortunately, despite its ability to adapt to dry climate, this banana cultivar is susceptible to most destructive disease of banana, especially to blood diseaae of banana (BDB). It was not surprising that when an outbreak of this disease took place in the island in early 2000s, it was this banana cultivar that was suffered the most. This article was based on a research project conducted in 2019, aimed at determining impacts caused by the outbreak to local economy, especially to food security, and understanding responses of the local governments to the outbreak. The study employed a mixed method approach, in which data were collected through a survey by interviewing 63 farmers, community leaders, and government officers. The resulting quantitative data were analyzed using descriptive statistical analysis, whereas the qualitative data were subject to thematic analysis. Results of the analysis indicated that the BDB outbreak severely impacted the local food security in particular and the local economy in general. The outbreak was still ravaging, kept spreading, destroying bananas in the island, especially the Musa ABB Pisang Kepok known locally as Pisang Marmi. The district government where the outbreak first started did take the necessary control measures. However, such control measures was taken too late after the disease had spread out throughout the district, allowing the disease to spread further East destroying bananas in the hree other districts. In addition, the participation of local farmers in controlling the disease was low because lack of information, limited available resources, and governance regime that far from collaborative, not too mention adaptive. Who finally suffered the most were small-scale farmers whose food and income depended heavily on bananas. The kept-spreading disease posed similar threats to farmer is nearby islands of Flores and Timor.
Abstract. Ulilalbab AR, Widinugraheni S, Masanto, Subandiyah S, Wibowo A. 2022. Expression of SIX1b and SIX1c effector genes and banana resistance genes during Foc TR4 infection on banana cultivars. Biodiversitas 23: 5314-5322. The relative expression SIX1 genes isolates of Foc TR4 and banana resistance genes have not been intensively studied. This study aimed to determine the expression of SIX1 genes of Foc TR4 and banana resistance genes. Twelve Foc TR4 isolates were collected from several regions in Indonesia. DSI analysis was performed to categorize their virulence levels. The representative Foc TR4 isolates from different virulence levels were artificially inoculated on the Musa acuminata Colla Cavendish subgroup and cv. Barangan and incubated for 48, 72, and 96 HPI. The expressed genes were quantitatively analyzed using the qPCR technique using primers to amplify SIX1b, SIX1c, chitinase, and PR-protein 1 genes. The results categorized the virulence of Foc TR4 isolates into moderate, virulent, and high virulent. The isolates of KJG and Batu-4 were selected for gene expression study representing moderate and high virulent groups, respectively. The results of in planta assay found that the expression of SIX1b, SIX1c, chitinase, and PR-protein1 was upregulated on the inoculated plants during the incubation period. However, the expression of these genes was increasingly upregulated in both bananas at early-stage inoculation. We assumed that plant defense genes of bananas might actively encounter the common virulence mechanisms of Foc TR4 at the initial stage of inoculation.
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