Brazil

This is a highly innovative and truly ground breaking research project devised by scientists based at Embrapa Wheat, Soybean, Genetic Resources and Biotechnology and Bioinformatics in Brazil and Rothamsted Research in the UK. The problem to be addressed is the control of a fungal disease called Fusarium head blight (FHB) which is one of the most serious and hazardous crop diseases worldwide. The main consequence of FHB is that trichothecene mycotoxins, such as deoxynivalenol (DON), accumulate in the grain, presenting a health risk to humans and animals. In Southern Brazil, where 90% of Brazilian wheat is grown, severe FHB epidemic years occur at a minimum of every 4 or 5 years. Legal limits have been set on the DON levels permitted in harvested grain used for different purposes. However, even moderate FHB years are highly problematic causing the lack of available safe grain for use either on farms or for sale into the market. For low income Brazilian farmers, FHB disease reduces the standards of living of farmer's families and that of their local communities. There is a pressing need to develop novel and effective FHB control options. In this project, we intend to take a novel whole fungal genome and disease modelling guided approach to develop a pipeline of genetically modified wheat genotypes harbouring T-DNA constructs, which can silence Fusarium genes critical for wheat infection via host-induced gene silencing (HIGS). We also intend to determine the plant and fungal mechanisms that control the HIGS phenomenon. HIGS could be used to control multiple pathogens. This project has six main research steps. 1. To explore using next generation sequencing the genomes of the five FHB causing species in Southern Brazil. Define the core and species-specific proteome of the FHB species complex (FGSC) for the development of molecular diagnostic tools and the selection of HIGS targets. Monitor for possible genome alterations over 3 years. 2. To enhance FHB disease risk forecasting, by establishing a spore sampler network that can detect and quantify Fusarium species. Devise and use diagnostic assays to identify and monitor FGSC diversity. Sample atmospheric Fusarium spores to identify potential inoculum sources and population structure. Incorporate data on the dynamics of airborne Fusarium spore populations into the existing regional FHB risk model. 3. To develop various T-DNA based constructs to silence Fusarium gene expression by HIGS, thereby controlling Fusarium infections. Evaluate single gene HIGS constructs using a novel cut wheat tillers (transient assay) and via stable transformation into Arabidopsis or lettuce. Two lead HIGS constructs targeting multiple Fusarium genes will be transform into a moderately FHB resistance Brazilian wheat cultivar. In the resulting transgenic plant populations, FHB severity and DON levels will be quantified. 4. To explore the underlying mechanisms of HIGS three cutting edge experiments will be completed. We will establish if long or short RNA molecules move between fungal and wheat cells, determine if the gene silencing phenomena once initiated operates systemically and investigate if transported RNA molecules are cargoed using vesicular transport to the plant cell surface for delivery into fungal cells. 5. To perform two years of GM wheat trial in two locations in Brazil using the four best HIGS lines and three appropriate control lines. Assess in-field FHB symptoms, airborne inoculum, grain quality, DON contamination and fungal spore production. To collect Fusarium isolates able to cause any disease on the HIGS lines and complete a full genome analyse. 6. The research team will engage with farmers, farmer co-operatives, grain purchasers, plant breeders in Brazil and the UK and academics globally to explain the project, the research findings and discuss ways to implement the new modelling/forecasting technologies, to use the novel GM trait and further understand the HIGS phenomenon.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Wildfires have become the new norm in many parts of the Amazonian humid forest, an ecosystem that did not co-evolve with this stressor. Large areas of previously undisturbed and human-modified forests are catching fire, jeopardising the future of the largest and most biodiverse tropical rainforest in the world, and potentially acting as a feedback that would further increase regional and global climate change. In recent dry years the extent of fire has greatly exceeded the rate of deforestation in the Brazilian Amazon. These fires result in in about half of the trees dying, and open up the forests to make them more vulnerable to subsequent fires. Despite the growing prevalence of Amazonian wildfires, we still have a very limited understanding of why these low intensity understorey fires cause such high rates of tree mortality, which species functional traits predict vulnerability or survival to these fires, what are the impacts of wildfires on the forest carbon balance and what are the patterns of taxonomic and functional recovery following a fire event. We propose a research plan to achieve major advances in our understanding of such wildfire impacts, including of the underlying mechanisms that cause both short-term and longer-term tree mortality. This work will be based at a field site in Santarem in Eastern Brazilian Amazonia, where we have collected several years of measurements of detailed vegetation ecology and carbon cycle tracking over a range of plots. These include a number of plots which experienced fire during the 2015/16 El Niño. We will implement this project by combining a state-of-the-art forest burn experiment with continued monitoring of a unique set of long-term sampling plots, some of which we have tracked through the 2015-16 wildfire event associated with a strong El Niño. We are uniquely placed to address these fundamental questions given our network of burned and unburned forest plots that is already in place, the strong partnerships we have forged with park managers and federal agencies, and the numerous past datasets that we can use as baseline information. The fire experiment will involve setting fire to limited patch of forest (with the close cooperation of local fire brigades), tracking fire intensity and tracking the physiology and mortality responses of individual trees in the fire plots, including trees that have their root mats or their bark insulated from fire damage. We will also experiment with different fire break methodologies to explore the most effective way to stop such fires. With the intensive carbon cycle studies we will track the carbon cycle responses for up to seven years after the 2015 fires, giving us novel insight into the longer term carbon cycle responses and the ecosystem responses and recovery after a fire event. As well as advancing scientific knowledge about a pervasive and increasing threat to the future of tropical forests in the Anthropocene, our co-designed pathways to impact ensures we will also inform and improve approaches to minimise risk of fire-induced dieback of humid Amazonian forests. We will work closely with local fire managers, and engage with state and national policymakers, to draft recommendations on how to manage forest reserves and forest-agriculture mixed landscapes to minimise the risk of fire spread. If applied at a large scale, these fire prevention strategies are a crucial tool that can help minimise the risk of extensive fire-induced dieback within Amazonian forests.

Predicting the effects of climate change, and especially drought, on rain forest tree mortality and the associated emissions of carbon dioxide (CO2) is an urgent and high-priority task which this project seeks to address. Increases in tree mortality have the potential to substantially increase total CO2 emissions to the atmosphere, but to date our models are not capable of representing the mortality process reliably during drought and we propose to combine new data and modelling to address this deficiency. The incidence of extreme drought events has increased in recent years, and climate predictions suggest that some tropical regions may be at risk this century. Severe drought has been associated with El Nino events in tropical South America and in SE Asia in the last 30 years. More recently, two 1-in-100 yr drought events have occurred in Amazonia in the past 10 years, adding weight to concerns about future shifts in climate and their impacts. At the same time, the incidence of widespread increased tree mortality associated with drought has been recognised as globally important. Severe drought in tropical rain forests can have a large impact. For example, in Amazonia, the regional drought of 2005 is thought to have halted the ongoing large net carbon sink by reducing tree growth and increasing tree mortality. At a larger, pan-tropical scale, observations of the impact of severe drought on tropical rain forests have yielded a startling result: not only do mortality rates increase by up to 12 fold during drought, but the impacts differ substantially between SE Asia and Amazonia. Apparently the rain forest trees of SE Asia are more vulnerable to drought than those of Amazonia. In addition, some taxa and tree sizes (e.g. species and genera, and especially large trees) differ in their vulnerability. If we are to understand the effects of drought on the world's rain forests, and to predict their future composition and functioning (e.g. in how they affect atmospheric CO2 concentration), then we need to know why regions and species differ in their vulnerability to drought. To make these predictions we need to incorporate ecological understanding into vegetation models that can be coupled to global climate models, to form Earth System Models (ESMs). The only way to enable these vegetation models to represent ecology properly is to make measurements in natural rain forests. To understand the impact of drought we must go a step further and experimentally manipulate the moisture available to the forest, in order to understand the responses of each key process (e.g. respiration, photosynthesis etc). Large-scale drought experiments are scientifically powerful, but very rare in any biome. We have created a unique opportunity in this project to combine the results from two tropical rain forest drought experiments, in Amazonia and Borneo. The combination of experimental and modelling expertise in our team is particularly strong and we wish to use it to make a substantial advance in the prediction of the impacts of drought on 21st century rain forest functioning. We will first use our models to test for physical differences (soils or climate) in Borneo and Amazonia. Secondly we will focus on differences in mortality risk among tree taxa (species or genera) within and between regions, as some are more vulnerable than others to drought. We will focus on measuring whether mortality is associated with the loss of supply of water or carbon, or a mixture of both, and incorporate our results into our models. In summary, we will use a powerful combination of tropical rain forest field experiments and global vegetation modelling to explain large observed differences in rain forest tree vulnerability to drought across Borneo and Amazonia. The outcome will have pan-tropical application and we will use it to improve predictions of how climate change will affect the global role of tropical rain forests in the 21st century carbon cycle.