The seriguela (Spondias purpurea) and umbuzeiro (Spondias tuberosa), trees commonly found in Brazil’s northeastern semi-arid region, and the Brazilian chestnut, native to the Cerrado, are part of a group of plants in Brazil that could help agriculture face two of the consequences of climate change: increasing temperatures and water shortages in some regions. This is because these three species have enhanced adaptive capacity and are heat and drought tolerant.
Identification and isolation of the genes that provide these plants with such tolerance could help to make crops such as soybean, maize, rice and beans equally resistant to climate extremes, said Eduardo Assad, agricultural engineer at the National Center for Technology Research in Computer Sciences (CNPTIA) at the Brazilian Agricultural Corporation (Embrapa) in a lecture presented at the fourth meeting of the 2014 Biota-FAPESP Education Conference Cycle, held on May 22 in São Paulo.
“The Cerrado used to be much hotter and dryer, and trees such as the pau-terra (Qualea parviflora Mart.), pequi and Brazilian yellow poinciana (Peltophorum dubium), not to mention the Brazilian chestnut, all survived,” Assad said. “We need to study the genomes of these species so we can identify and isolate the genes that make them so adaptable.” Once this has been accomplished, the next step will be to introduce them into plants such as soybean and maize, making them similarly resistant. “It won’t be easy, but we need to get started,” he said.
Assad noted that Brazil is home to the largest known variety of heat and drought resistant species. And enhancing the capacity to withstand water shortages and increased temperatures is one of the great challenges facing Brazilian agriculture. After all, simulations of future scenarios developed by Embrapa suggest that the reduced productivity observed in crops such as maize, soybean and rice due to climate change is expected to become more pronounced in the coming decades. “These scenarios apply to current genetic varieties,” Assad explained. “One possible solution is to look for alternative genes to work on improving [these varieties],” he said.
As an example of the contribution by Embrapa’s National Center for Soybean Research, Assad presented a genetically modified soybean variety to be introduced in 2015. This variety contains a gene called DREB (dehydration responsive element binding) that encodes a protein responsible for activating a plant’s natural defenses against lack of water. Patented by the Japan International Research Center for Agricultural Sciences (JIRCAS), this gene was extracted from a plant in the mustard family, the Arabidopsis thaliana, the first plant to have its genome sequenced. In soybeans, this gene seems to increase resistance to water shortages. “We’ve tested it this year in Paraná during a terrible dry season,” he explained. “Studies still need to be done, but things are going quite well.”
Assad also mentioned progress made by the Agronomic Institute of Paraná (IAPAR), which has already introduced four heat-tolerant bean cultivars, in addition to conducting studies in the municipality of Varginha (state of Minas Gerais) in search of more heat-tolerant varieties of coffee.
Embrapa’s calculations based on average soybean productivity show that this grain alone accrued more than US$8.4 billion in losses related to climate change in Brazil between 2003 and 2013. Corn production lost more than US$5.2 billion during the same period.
Studies conducted at Embrapa and the University of Campinas (Unicamp) also suggest that there will be a reduction in the area conducive to the planting of some crops in coming years. These analyses predict that the number of low-risk areas for the cultivation of Arabica coffee is expected to diminish by 9.45% by 2020 and by 17.15% by 2050, causing losses of R$882 million and R$1.6 billion, respectively.
In the face of such losses, another suggestion by Assad is to overhaul the agricultural production model. “The concentration of greenhouse gases in the atmosphere has increased over 20% in the last 30 years, making implementation of cleaner production systems critical,” he told Agência FAPESP. “Brazil is highly respected with regard to this topic, particularly because it has managed to both reduce deforestation and increase productivity in the Amazon region,” he said.
According to Assad, this situation opens up channels for dialog about sustainable agriculture and the adoption of strategies such as the integration of crops, cattle-raising areas and forests; direct planting in straw; the use of nitrogen-fixing bacteria in the soil; the use of stone meal (which contains micro- and macro-nutrients, to improve soil fertility); the application of organomineral fertilizers; and genetic improvements.
“Cattle confinement is another subject for discussion by researchers and livestock farmers in many parts of the world,” Assad noted. To diminish the risk of contamination among confined herds, an alternative is to restore degraded pastures. Studies conducted at Embrapa’s Agrobiology Unit show that meat production in recovered pastures is able to reduce greenhouse gas emissions nearly ten-fold.
“Environmentalists, land owners, the government and the private sector need to sit down and decide what to do from this point on,” Assad said. “What production system will they use? Will it include pastures or not? Will it include trees or not? Will it be rotated or not? These are difficult long-term changes, but many farmers are already concerned about these issues and the losses that global warming could bring, and they are beginning to look for solutions,” he said.
The consequences of climate change on Earth are not expected to be restricted to agriculture. In highly degraded ecosystems such as the Atlantic Forest, many tree species may also lose area as a result of the increase in the average temperature of the Earth’s surface that is expected in the coming decades. In his lecture, biologist Alexandre Colombo showed what is likely to happen to 38 tree species that are native to the Atlantic Forest by the middle of this century.
Colombo used data on the distribution of these 38 species, collected at 2,837 sites in Brazil, to feed into a mathematical model that considered the temperature changes anticipated in the next few decades. Under the optimistic scenario, in which the average temperature of the Earth’s surface is expected to increase by two degrees, 32 species could see a significant reduction in their area of distribution by 2050; on average, the area of occurrence of these species could be reduced by 25%. Under the pessimistic scenario, in which the temperature increases by four degrees, the area of occurrence of 19 species could shrink by more than 50%.
The reduction of the environment suitable for survival is expected to have a particular effect on trees such as the juçara palm (Euterpe edulis) and the Perkins pepper tree (Mollinedia schottiana), according to Colombo’s study, carried out under the coordination of Carlos Alfredo Joly, a professor at Unicamp and coordinator of Biota-FAPESP.
Of the 38 species examined in this study, published in the Brazilian Journal of Biology in 2010, the one most likely to lose area is the guaricica (Vochysia magnifica), a tree that can grow to nearly 25 meters in height. The distribution of this tree could suffer a brutal 73% reduction. Currently found in the South and the Southeast, the guaricica may eventually grow only in western Santa Catarina State and northern Rio Grande do Sul State if the temperature rises four degrees by 2050.
The researchers are currently also collaborating with teams from the University of São Paulo (USP) and the National Institute for Space Research (INPE), with support from Petrobras, to look into what is likely to happen to the distribution of 81 tree species in the different Brazilian biomes between now and 2100.
As a strategy for reducing the potential impact of climate change on the planet, Colombo proposes investment in preservation of forest remnants and reforestation of areas where the natural vegetation has been degraded. He also suggests the creation of corridors to connect the fragments of native vegetation.
Biologist Leonardo Dias Meireles, a professor at the School of Arts, Sciences and Humanities at USP, explained in his lecture how models of potential geographic distribution of a species are constructed. Since they take into consideration environmental and climatic variables of places where the species have already been found, these models enable researchers to identify, for example, new areas with conditions similar to those of their current environment. Thus, it is possible that a species’ potential area of occupation could serve as a guide to its collection or even conscious reintroduction into the environment. As an example, he cited the case of the casca-d’anta (Drimys brasiliensis), which was recently found in a section of southeastern Goiás State, as indicated by models developed by Meireles during his doctoral studies under George Shepherd at Unicamp.
According to Meireles, these models are important for estimating gains or losses in a species’ area of occurrence and for determining how it might respond to climate change. They also aid in the identification of areas that are climatically favorable to the establishment of new populations in the future, and facilitate the design of flora and fauna preservation strategies.
The conference cycle organized in 2014 by the Research Program in Identification, Conservation, Recovery and Sustainable Use of Biodiversity in the State of São Paulo focuses on ecosystem services. The final meeting in the series, scheduled for June 25, 2014, will discuss the topic “Biodiversity and nutrient cycling.”Republish