Sequencing the Major Mycosphaerella Pathogens of Wheat and Banana

Mycosphaerella is one of the largest genera of plant-pathogenic fungi with more than 1,000 named species, many of which are important pathogens causing leaf spotting diseases in a wide variety of crops including cereals, citrus, banana, eucalypts, soft fruits and horticultural crops. A few species of Mycosphaerella cause disease in humans and other vertebrates. An international project was initiated to sequence the genomes of M. graminicola and M. fijiensis, two of the most economically important pathogens of wheat and banana, respectively, along with 40,000 ESTs from M. fijiensis and the related maize pathogen Cercospora zeae-maydis. The 9x M. graminicola genome size is 39.8 Mb with chromosome sizes from 548 kb to 6 Mb and a complete circular mitochondrial genome of 43,947 bp. Our data indicate that M. graminicola has both the largest chromosome number and the smallest chromosome sizes recorded among filamentous ascomycetes. The Mycosphaerella Genomics Consortium, which was established in 2003, decided to use M. graminicola as the model to develop more genetic and genomic research on M. fijiensis. Since 2003, M. fijiensis EST sequencing has resulted in more than 30,000 ESTs, and the genome sequencing was recently finished at 7.8x. The genome size of M. fijiensis is 80% larger than that of M. graminicola. The completed mitochondrial sequence is more then twice as large, and the estimated nuclear genome size is approximately 72 Mb. The extension of the genome size of M. fijiensis seems to be mostly due to additional repeated sequences. The status of Mycosphaerella sequencing will have a significant effect on future studies aimed at the control of black leaf streak disease. The current status of both sequencing projects and other initiatives to exploit this information and to put it into a multidisciplinary approach focusing on sustainable management of the disease will be discusse

Het graanziekteonderzoek in Nederland: kaalslag in de polder (2)

Geschiedenis, verworvenheden en bedreiging van het nationale graanziekteonderzoek (roest in tarwe) in Nederland. Rubrieken in dit artikel: 1) Resistentieonderzoek; 2) Certificering en inputreductie; 3) Ziekteninventarisatie. Gegevens in bijgaande tabel: Incidentie van diverse graanziekten in Nederland (periode 1981-1983, 1994-2001

Identification of a new resistance gene to septoria tritici blotch in wheat

Door het screenen van lijnen en wilde verwanten van tarwe, is een nieuw resistentiegen tegen STB (Septoria tritici blotch) gevonden

Agrobacterium-mediated transformation of Mycosphaerella fijiensis, the devastating Black Sigatoka pathogen of bananas

Mycosphaerella fijiensis, M. musicola en M. eumusae veroorzaken de Sigatoka-ziekte in banaan. Op dit moment is de toepassing van fungiciden de enige optie om deze ziekte te bestrijden. Het PRPB (Pesticide Reduction Program for Banana) investeert in de ontwikkeling van technieken voor de genotype- en fenotypebepaling van M. fijiensis. Hierbij wordt gebruikt gemaakt van ATMT (Agrobacterium tumefaciens-mediated transformation)

A molecular diagnostic for tropical race 4 of the banana

This study analysed genomic variation of the translation elongation factor 1 (TEF-1) and the intergenic spacer region (IGS) of the nuclear ribosomal operon of Fusarium oxysporum f. sp. cubense (Foc) isolates, from different banana production areas, representing strains within the known races, comprising 20 vegetative compatibility groups

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

Factors Affecting the Utilisation of Improved Ventilated Latrines Among Communities in Mtwara Rural District, Tanzania.

The Tanzania government, working in partnership with other stakeholders implemented a community-based project aimed at increasing access to clean and safe water basic sanitation and promotion of personal hygiene in Mtwara Rural District. Mid-term evaluation revealed that progress had been made towards improved ventilated latrines; however, there was no adequate information on utilisation of these latrines and associated factors. This study was therefore conducted to establish the factors influencing the utilisation of these latrines. A cross-sectional study was conducted among 375 randomly selected households using a pre-tested questionnaire to determine whether the households owned improved ventilated latrines and how they utilised them. RESULS: About half (50.5%) of the households had an improved ventilated latrine and households with earnings of more than 50,000 Tanzanian Shillings were two times more likely to own an improved latrine than those that earned less (AOR 2.1, 95% CI=1.1-4.0, p= 0.034). The likelihood of owning an improved latrine was reduced by more than 60 percent for female-headed households (AOR=0.38; 95% CI=0.20-0.71; p=0.002). Furthermore, it was established that all members of a household were more likely to use a latrine if it was an improved ventilated latrine (AOR=2.4; 95% CI=1.1-5.1; p= 0.024). Findings suggest adoption of strategies to improve the wellbeing of households and deploying those who had acquired improved ventilated latrines as resource persons to help train others. Furthermore, efforts are needed to increase access to soft loans for disadvantaged members and increasing community participation

Outstanding : the dispensable chromosomes of Mycosphaerella graminicola

Bijdrage aan de KNPV-voorjaarsvergaderin

Mycosphaerella foliar diseases of bananas: towards an integrated protection

Mycosphaerella foliar diseases, Black Leaf Streak and Sigatoka diseases caused respectively by Mycosphaerella fijiensis and M. musicola, are by far the main parasitic constraints for export bananas. They result in substantial necrosis of the foliage and consequently yield loss, but - most importantly - in immature ripening that renders bananas unfit for export. In the absence of commercial resistant varieties, banana exports can only be achieved through intensive chemical control. In most countries, fungicides are applied systematically following a fixed-schedule treatment programme (40-60 applications/year) to protect the young leaves against infection. In some places, forecasting systems are used to schedule treatments in function of the stage of evolution of the disease (5-14 treatments/year). In all countries chemical control has to face increasing difficulties in terms of efficacy, cost and environmental impact. This situation results mainly of two major events: (i) the development of fungicide resistance to systemic fungicides that lead to a systematic use of protectants and (ii) the evolution of the legislation which becomes increasingly restrictive. New alternatives that must be associated with basic prophylactic measures such as the mechanical ablation of lesioned leaves are needed for a sustainable control of these diseases. They are presented as (1) short-term solutions: implement the forecasting strategy where it is feasible or introduce fungicides with low negative environmental effect where this forecasting strategy is impeached by fungicide resistance; (2) mid-to-long-term solution: develop and introduce resistant cultivars in the cropping system. (Résumé d'auteur