Workshop 3: Pests and diseases in bananas - projecting the effects of climate change.

Over several decades, ProMusa has addressed important disease threats such as black leaf streak (black Sigatoka), Fusarium wilt, banana streak viruses and Banana bunchy top virus

Dispersal limitation and fire feedbacks maintain mesic savannas in Madagascar

Madagascar is regarded by some as one of the most degraded landscapes on Earth, with estimates suggesting that 90% of forests have been lost to indigenous Tavy farming. However, the extent of this degradation has been challenged: paleoecological data, phylogeographic analysis, and species richness indicate that pyrogenic savannas in central Madagascar predate human arrival, even though rainfall is sufficient to allow forest expansion into central Madagascar. These observations raise a question—if savannas in Madagascar are not anthropogenic, how then are they maintained in regions where the climate can support forest? Observation reveals that the savanna–forest boundary coincides with a dispersal barrier—the escarpment of the Central Plateau. Using a stepping-stone model, we show that in a limited dispersal landscape, a stable savanna–forest boundary can form because of fire–vegetation feedbacks. This phenomenon, referred to as range pinning, could explain why eastern lowland forests have not expanded into the mesic savannas of the Central Highlands. This work challenges the view that highland savannas in Madagascar are derived by human-lit fires and, more importantly, suggests that partial dispersal barriers and strong nonlinear feedbacks can pin biogeographical boundaries over a wide range of environmental conditions, providing a temporary buffer against climate change

Droughts and the ecological future of tropical savanna vegetation

1. Climate change is expected to lead to more frequent, intense and longer droughts in the future, with major implications for ecosystem processes and human livelihoods. The impacts of such droughts are already evident, with vegetation dieback reported from a range of ecosystems, including savannas, in recent years. 2. Most of our insights into the mechanisms governing vegetation drought responses have come from forests and temperate grasslands, while responses of savannas have received less attention. Because the two life forms that dominate savannas—C3 trees and C4 grasses—respond differently to the same environmental controls, savanna responses to droughts can differ from those of forests and grasslands. 3. Drought‐driven mortality of savanna vegetation is not readily predicted by just plant drought‐tolerance traits alone, but is the net outcome of multiple factors, including drought‐avoidance strategies, landscape and neighborhood context, and impacts of past and current stressors including fire, herbivory and inter‐life form competition. 4. Many savannas currently appear to have the capacity to recover from moderate to severe short‐term droughts, although recovery times can be substantial. Factors facilitating recovery include the resprouting ability of vegetation, enhanced flowering and seeding and post‐drought amelioration of herbivory and fire. Future increases in drought severity, length and frequency can interrupt recovery trajectories and lead to compositional shifts, and thus pose substantial threats, particularly to arid and semi‐arid savannas. 5. Synthesis. Our understanding of, and ability to predict, savanna drought responses is currently limited by availability of relevant data, and there is an urgent need for campaigns quantifying drought‐survival traits across diverse savannas. Importantly, these campaigns must move beyond reliance on a limited set of plant functional traits to identifying suites of physiological, morphological, anatomical and structural traits or “syndromes” that encapsulate both avoidance and tolerance strategies. There is also a critical need for a global network of long‐term savanna monitoring sites as these can provide key insights into factors influencing both resistance and resilience of different savannas to droughts. Such efforts, coupled with site‐specific rainfall manipulation experiments that characterize plant trait–drought response relationships, and modelling efforts, will enable a more comprehensive understanding of savanna drought responses

A raça 4 tropical de Fusaruim oxysporum f. sp. cubense: riscos e impactos potenciais para a bananicultura brasileira.

O surgimento da raça 4 tropical de Fusarium oxysporum f. sp. cubense (FocR4T) tornou a Fusariose da bananeira a maior ameaça da bananicultura mundial. Apesar de FocR4T não ter sido ainda relatada nas Américas, o risco de sua introdução é iminente. Este trabalho objetivou estimar o potencial de riscos e impactos econômicos de uma eventual incursão de FocR4T no Brasil. Foi analisada a distribuição geográfica e impactos causados por FocR4T em nível global, a resistência/susceptibilidade das variedades presentes no Brasil, bem como a capacidade de vigilância e efetividade de barreiras fitossanitárias. Avanços e iniciativas em pesquisa e desenvolvimento também foram analisados. As principais variedades (Prata, Nanica e Maçã) são suscetíveis a FocR4T e até o momento não há variedades resistentes disponíveis. O nível de conscientização sobre FocR4T e a preparação do setor ante um eventual surto da doença são inadequados. Há capacidade de diagnóstico de FocR4T e pesquisas para a obtenção de variedades resistentes e manejo de eventuais surtos da doença estão em curso. Todavia, são necessários mais investimentos para disponibilizar soluções em um prazo menor. É urgente reforçar ações visando a exclusão e detecção precoce de FocR4T no Brasil, bem como elaborar um plano nacional de contingência

From technology adoption to understanding innovation: lessons from plantain innovation systems in four countries

Plantain is an important staple food and cash crop in Latin America and West Africa with growing market demand. In recent decades, new production technologies and varieties have become available and are being tested in major producing countries. The purpose of the project ‘Intensification of plantain production in Latin America and West Africa” which results are presented on this poster was 1) to identify determinants for successful technological change for intensification in plantain production and bottlenecks in the socio-economic and market context, and innovation and seed systems in Latin America and 2) analyze how these elements are relevant under conditions in West Africa, so as to contribute to intensification and off-season plantain production for West African smallholders

Endophyte microbiome of banana roots reveals high diversity and potential for agricultural uses

Similar to humans, plants are populated with different sets of microorganisms with potential roles on host and ecosystem functions. Endophytic microorganisms colonize root tissues inter- and/or intracellularly producing a wide range of compounds useful for plants growth as well as for protection against biotic and abiotic stresses. Clonally propagated crops such as banana are frequently multiplied by using tissue culture techniques in order to get uniform, pathogen-free plants. This process, however, also eliminates the endophyte beneficial microbiota and might have their fitness altered. To understand the microbial functional diversity of Musa spp., and its potential application in banana production systems, root-associated endophytic microorganisms (360 bacteria and 143 fungal) were isolated from 20 Musa spp. genotypes of the ex situ collection in CORBANA, Guapiles, Costa Rica. Analyses of specific genome regions (16S rDNA for bacteria and tefa-1á or ITS for fungi) revealed 21 different bacterial genera, with Klebsiella, Enterobacter, Bacillus, Acinetobacter and Burkholderia as the most frequent. Trichoderma spp. and Fusarium oxysporum prevailed among the 12 genera of fungi identified. Most isolates are known to be associated with banana, but genera such as Sphingobacterium, Grimontella, Providencia, Pleosporaceae have not been reported previously. Microorganisms with no significant similarities to the analysed database (04 bacteria and 03 fungi) were found and will probably constitute new descriptions. Some endophytes were more frequent or uniquely found on certain banana genotypes, but endophyte-host specificity needs to be further verified. Partial characterisation of the collection showed that T. asperellum isolates from cv. Yangambi Km5 (AAA) can significantly inhibit (up to 80.5 %) the mycelial growth of the banana pathogen Fusarium oxysporum f. sp. cubense. When a set of selected bacteria was inoculated in the tissue culture plants of the commercial cultivar Cavendish, three bacterial isolates (Bacillus aryabhattai, Burkloderia spp. and unknown) significantly increased the dry root weight. These results revealed a high and multifunctional diversity of culturable endophytes from Musa spp. roots, with a strong potential for new product developments and methods to enhance productivity in banana. Opportunities also exist to explore Musa genotypes in their native habitat and to characterise non-culturable microorganisms

Raízes de Musa spp. hospedam fungos endofíticos com potencial de controle de Fusarium oxysporum f. sp. cubense.

Aiming to understand the role of root-associated endophytic fungi against Fusarium oxysporum f. sp. cubense (Foc) we screened 25 non-commercial genotypes of Musa spp. from field collections in Brazil and Costa Rica. Analyses of Tefa-1? and/or ITS genome regions of the 150 isolates obtained revealed that most frequent genera were Trichoderma spp. and F. oxysporum. Fungi such as Gloeotinia temulenta and others isolates with no significant similarities to the database analysed are potentially new descriptions. Some genera were more frequent or uniquely found on certain genotypes, but endophyte-host specificity needs to be verified. Antagonism tests against Foc revealed that most Trichoderma isolates are better competitors than Foc in vitro. T. asperellum isolates showed the highest inhibition (> 80%) and parasitism (100%) levels. Some T. asperellum isolates were also able to parasite non-pathogenic F. oxysporum isolates even coming from the same host. Our results revealed that Musa spp. roots are hosts of a high diversity of culturable fungi including potential biocontrol agents against Foc, but also indicate complex in planta interactions among endophytes

Agrobiodiversity and climate change: what do students need to know?

Key note paper presented at 2nd ANAFE International Symposium: ‘Mainstreaming climate change into agricultural education: tools, experiences and challenges’, Malawi, 2008. The paper informs that adaptation of production systems to climate change requires human capacity in agricultural biodiversity but a 2007 survey in African universities showed that education in this area is weak or absent. The authors argue that role of agricultural biodiversity in adaptation to climate change should be better understood, and that universities should seek to develop such competencies in their students. Universities should review curricula to include agricultural biodiversity dimensions through innovative, experiential teaching methods and active student participation

Reading Disability as a Condition of Family Stability

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72295/1/j.1545-5300.1964.00066.x.pd