Scientists have genetically engineered the metabolism of plants to grow faster and produce 40 percent more biomass. They want to tackle a problem of a global dimension.
Plants master an amazing trick: they only need carbon dioxide from the atmosphere, some water and energy from sunlight to build the substances that make them up. At the same time, the process releases the oxygen that humans and animals need to breathe. Without the photosynthesis, life on earth would not be possible, almost all the biomass goes back to this process. However, it does not always run optimally.
In about twenty percent of cases, the enzyme RuBisCO makes a mistake and absorbs oxygen instead of carbon dioxide. This creates a poisonous by-product for the plant, which must be laboriously decomposed by light breathing. This costs the plants a lot of energy.
US researchers have now succeeded in making the process of photosynthesis significantly more effective, they report in the journal „Science“. They changed the genes in tobacco plants so that the light breathing was much shorter and less expensive. For this purpose, the scientists used genes of the giant pumpkin (Cucurbita maxima) and of a green algae species (Chlamydomonas reinhardtii). Tobacco is a model plant popular among biotechnologists, among other things because it grows fast and produces many seeds.
„Feed 200 million more people“
In nature, light breathing takes place in various organelles of the plant cells, including the photoactive chloroplasts. The researchers now blocked a transporter protein, leaving the metabolism in the chloroplast. This results in a smaller amount of toxic by-products. As a result, the plant needs less energy for light breathing and can grow faster.
„We could feed up to 200 million more people with the calories lost in the US Midwest through photorespiration,“ said Donald Ort, of the University of Illinois, who has been involved in the study.
The biotechnologists tested their procedure by planting the modified tobacco plants not only in greenhouses but also in fields. Compared to untreated tobacco, the manipulated plants produced an average of 41 percent more biomass. For a better comparison, the plants were previously dried.
The researchers have now started using their findings to increase the yield of soybeans, cowpeas, rice, potatoes, tomatoes and eggplant. They hope for better harvests. The genetically modified plants will later be made available to small farmers in many regions of the world free of charge, the researchers assure.
„The synthetic pathway holds the potential for a leap forward in yield improvement through genetic modification of crop plants,“ write the researchers Marion Eisenhut and Andreas Weber of the University of Düsseldorf, who were not involved in the study, in a commentary to the study. At present, the annual yield increases of plants are less than two percent.
