Science Concentrates BIOTECHNOLOGY
Engineering crops to be more efficient that if photorespiration were eliminated, From an engineering point of view, photofarmers in the midwestern US would synthesis is inefficient. One out of every produce 320 trillion more calories from five tries, the enzyme that plants use to their crops annually on the same amount catch carbon dioxide mistakenly grabs on of land (Annu. Rev. 2016, DOI: 10.1146/ to oxygen, producing toxic glycolate inannurev-arplant-043015-111709). stead of carbohydrate building blocks. This The research was led by Paul South, a misstep is called photorespiration. Plants use a tremendous amount of precious ener- molecular biologist with the US Departgy to correct it. In fact, photorespiration re- ment of Agriculture Agricultural Research Service and who is based at the University duces crop yields by an estimated 20–50%. of Illinois at Urbana-Champaign. Now researchers have demonO He and his collaborators tested a strated a better way to correct OH novel pathway that added a glythis photosynthetic error. Tobac–O colate-processing enzyme from co plants that were genetically the algae Chlamydomonas and a engineered to more efficiently Glycolate malate synthase from a pumpkin, break down glycolate showed 40% and blocked some aspects of native phogreater crop yields in field trials (Science torespiration. Part of the reason photore2019, DOI: 10.1126/science.aat9077). If the spiration is so costly for plants is that it findings can be replicated in food crops, farmers could produce more calories using requires transporting reactants between different compartments inside the cell less land and fertilizer. tens of times. The Illinois researchers “This is a demonstration that you used RNA interference to block the first can alter photorespiration in a fundatransport step, trapping glycolate in the mental way and get significant gains in chloroplast. There, the added enzymes yields—and that’s exciting,” says Berkley work in concert with native ones to free Walker, a plant biologist at Michigan State the carbons wasted in glycolate, forming University who was not involved with the research. Walker’s modeling work suggests two molecules of carbon dioxide.
C R E D I T: CL A I R E BE N JA MI N / R IP E P RO JECT ( F I E LD ) ; ACS NA NO/C& EN ( V I DEO )
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Correcting photosynthetic errors in tobacco increased crop yields 40% Engineered tobacco plants had higher yields and flowered earlier than conventional ones. The team engineered tobacco, which is a model crop plant, to express this new pathway. In 2017, the team conducted a large field trial of the tobacco. On average, the engineered plants yielded 40% more biomass at harvest than unmodified tobacco. Veronica Maurino, a botanist at Heinrich Heine University Düsseldorf who developed an earlier version of the genetic pathway built on by the Illinois group, says demonstrating yield increases in field studies is an important step forward. But researchers still need to determine whether these changes “will also boost productivity in other plant-crop species and in the parts of the plants that are used as food, such as seeds, roots, and fruits,” Maurino says. The Illinois group is now trying to engineer this pathway into soy and plants that are major sources of calories in the developing world, including cassava and cowpeas.—KATHERINE
BOURZAC
MOLECULAR MACHINES
Metal-free micromotor picks up heavy metals Micromachines can propel themselves through solutions by reacting with fuel in their environment. But most of these machines have relied on ultraviolet light and expensive noble metals like gold and platinum to drive these reactions. Now, researchers in the Czech Republic have made a simple, metal-free micromotor that operates under visible light (ACS Nano 2018, DOI: 10.1021/ acsnano.8b06914). Made from a nitrogen-containing variant of graphite called graphitic carbon nitride, the tubular micromotors can jet around in water (screenshots shown), adsorbing toxic heavy metals. The team hopes the tiny motors could one day perform tasks like cleaning wastewater. Learn more at cenm.ag/micromotors.—KERRI
JANSEN JANUARY 7, 2019 | CEN.ACS.ORG | C&EN
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