Stanford, CA— An international team of 12 leading plant biologists, including Carnegie’s Wolf Frommer, say their discoveries could have profound implications for increasing the supply of food and energy for our rapidly growing global population. All of their work focuses on the mechanisms that plants use for transporting small molecules across their membranes and thus for controlling water loss, resisting toxic metals and pests, increasing salt tolerance, and storing sugar.


Collectively, the group has discovered details about the biochemistry and genetics of plant transport proteins that could have a profound impact on global agriculture. In a perspective piece, published by Nature, the team argues that the application of their findings could help the world meet its increasing demand for food and fuel, as the global population grows from seven billion people to an estimated nine billion by 2050.


Wolf Frommer, director of Carnegie’s Plant Biology Department, has worked on plant transporters for over two decades and identified many of the key nutrient transporters in plants. He collaborated with 12 other scientists from Australia, Japan, Mexico, Taiwan, the U.S., and the U.K. on the paper.


Frommer and his colleagues state that many of the recent discoveries in laboratories around the world had previously been below the radar—known only to a small group of other plant biologists. By widely disseminating their findings, the team hopes to educate policymakers and speed the eventual application of their discoveries to global agriculture.


“Of the present global population of seven billion people, almost one billion are undernourished and lack sufficient protein, fats and carbohydrates in their diets,” the paper says. “An additional billion people are malnourished because their diets lack required micronutrients such as iron, zinc and vitamin A. These dietary deficiencies have an enormous negative impact on global health, resulting in increased susceptibility to infection and diseases, as well as increasing the risk of significant mental impairment. During the next four decades, an expected additional two billion humans will require nutritious food. Along with growing urbanization, increased demand for protein in developing countries coupled with impending climate change and population growth will impose further pressures on agricultural production.”


“Simply increasing inorganic fertilizer use and water supply or applying organic farming systems to agriculture will be unable to satisfy the joint requirements of increased yield and environmental sustainability, but rather increase ecological damage” the paper continues. “Increasing food production on limited land resources for sustainable production has to rely on innovative agronomic practices coupled to the genetic improvement of crops.”


Research from one member of the team has already allowed agricultural scientists to engineer wheat plants that are more tolerant to salt in the soil, boosting wheat yields by a whopping 25 percent in field trials.


Another recent discovery from the group opens up the potential to grow crops on the 30 percent of the earth’s soils that are currently unusable for agricultural production due to acidity, but that otherwise would be ideal for agriculture. In acidic soils, aluminum ions result in plant toxicity, damaging the root tips of susceptible plants and inhibiting root growth, which impairs the uptake of water and nutrients. The plant biologists now understand how transport proteins control this process. By engineering crops to convert aluminum ions into a non-toxic form, agricultural scientists could turn these now-unusable acidic soils into productive farmland.


Other recent transport protein developments described by the team could be used to improve the salt tolerance of crops, so they can be grown on previously productive farmland with brackish soil that now lies fallow. Still others could increase the storage of iron and zinc in food crops to improve their nutritive qualities.


The scientists also discovered plant transporters that allow crops to use phosphate—an element essential for plant growth and crop yield—more efficiently and to increase the uptake of nitrogen fertilizers, which are costly to produce. Nitrogen fertilizer production consumes one percent of global energy usage and poses the highest input cost for many crops. Yet only between 30 and 50 percent of applied nitrogen fertilizer is used by plants. The remainder can lead to production of nitrous oxide, a greenhouse gas, or disruption of aquatic ecosystems.


The biologists said crops could be made more drought resistant through discoveries in the plant transport proteins that regulate the pores on the surface of leaves, the channel through which plants lose more than 90 percent of their water.


Two other major goals in agriculture are increasing the carbohydrate content and pest-resistance of crops. A recent discovery in the Frommer lab, the identification of SWEET transporters that move sugar throughout the plant, has been used to develop rice plants that confer pest resistance to crops, providing a novel way to simplify the engineering of crops for both high yields and pest resistance.


The team was brought together by Julian Schroeder, a professor of biology at UC San Diego. In addition to Schroeder and Frommer, the co-authors of the paper are Emmanuel Delhaize of CSIRO in Canberra, Australia; Mary Lou Guerinot of Dartmouth College; Maria Harrison of the Boyce Thompson Institute for Plant Research in Ithaca, NY; Luis Herrera-Estrella of the Center for Research and Advanced Studies of the National Polytechnic Institute in Iraputo, Mexico; Tomoaki Horie of Shinshu University in Nagano, Japan; Leon Kochian of Cornell University; Rana Munns of the University of Western Australia in Perth; Naoko Nishizawa of Ishikawa Prefectural University in Japan; Yi-Fang Tsay of the National Academy of Science of Taiwan; and Dale Sanders of the John Innes Center, Norwich Research Park in the U.K.


Caption: Picture of wheat field by Karen Arnold provided courtesy of Research from one of the co-authors has already allowed agricultural scientists to engineer wheat plants that are more tolerant to salt in the soil, boosting wheat yields by a whopping 25 percent in field trials.

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Plant Genetics