When many people think about boosting yield through biotechnology, insect and disease resistance readily come to mind. But Tuesday’s 4 pm BIO panel on agriculture discussed a more significant factor in crop losses. In Saving Harvests, Lives & Livelihoods: Breakthroughs in Plant Stress Tolerance Technologies, the focus was on the problems of abiotic stress, and some potential solutions.
Plants, like all living organisms, exist in a narrow range of environmental conditions. Drastic changes in temperature, water availability, and excess salt in soils are examples of abiotic stress, or stress from non-living environmental factors. Panelist Julian Schroeder, a professor at UC San Diego, explained that crops currently only yield an average of 21% of their innate potential and 70% of the losses are due to abiotic stress
“Any conditions that move outside that narrow window of physiological conditions is stressful to the plants,” said Christine Foyer, Professor of Molecular Agriculture at the University of Newcastle, UK.
Foyer described her research into oxidative stress – or damage caused by highly reactive oxygen-containing molecules that are a byproduct of photosynthesis. She discovered a plant defective in a photosynthesis-related gene that not only suffered less oxidative stress, but surprisingly also resisted some viral infections.
Schroeder described his research into some of the stresses related to salty soils and water loss. He discovered a gene called AtHKT1, a sodium transporter that could be used to help plants become more salt tolerant. He also described how excessive water loss can occur through the stomata, which are small pores on the undersides of plant leaves.
“When they take in [carbon dioxide] they lose 95% of their water through these pores,” said Schroeder. He explained that the poor performance of some plants in drought conditions is due to insensitivity to Abscisic Acid, a plant hormone that signals the stomata to close. He discovered a gene in Arabidopsis that affects this process and can mean the difference between a living plant and a wilted one when conditions are dry.
The four panelists emphasized that with the advent of climate change, abiotic stresses will become more problematic – stressing the need for solutions to these problems. Rising levels of carbon dioxide in the atmosphere can also close the stomata of plant leaves, lessening their ability to take in needed CO2 for photosynthesis. Some progress has been made in identifying genes important in this process.
Identifying a potentially useful gene is only the first step in the process of developing a useful biotech crop improvement. Hagai Karchi, CTO of Evogen Ltd, described the stringent selection process that his company uses to weed through genes identified by a computer algorithm. Of every 100-150 genes discovered, on average just more than one makes it through all the steps of development. One such gene that made it is called evo133, which helped both tomatoes and maize resist the effects of drought.
Curt Brubaker, Genetics Group Leader at Bayer CropScience, explained that biotech approaches to addressing abiotic stresses are not the only way to address these problems. He highlighted the difficulties of tapping into the genetic diversity of old crop varieties, landraces, and wild relatives for improved traits. A recent technology called marker-assisted breeding, also known as “precision breeding,” is helping speed this process.
“How much improvement you can get in your breeding process per year?” Brubaker asked. By using statistics to associate desirable traits with specific locations in the genome, plants with the most desirable genes can be selected for the next generation. After an elite variety has been developed, these molecular markers can also be used to reduce the number of crosses necessary to breed biotech traits into the variety.
But without a robust breeding program, any traits developed through a biotech pipeline will be useless, he said. “Both of those parts of the equations have to be of equivalent quality.”
Michael Metzlaff, Crop Productivity Group Leader at Bayer CropScience, moderated the panel and took questions from the audience. He ended the discussion with a few remarks about the future contributions of genetic engineering toward protecting crops against abiotic stress.
“Green Biotechnology has reached a new level… Watch out. Molecular Genetics will definitely contribute to improvements in agriculture.”