Masa Iwanaga

Significance Globally, wheat farming is a major source of nitrogen pollution. Rapid generation of soil nitrates cause nitrogen leakage and damage ecosystems and human health. Here, we show the 3Ns b S chromosome arm in wild grass (Leymus racemosus) that controls root nitrification inhibitor production can be transferred into elite wheat cultivars, without disrupting the elite agronomic features. Biological nitrification inhibition (BNI)–enabled wheats can improve soil ammonium levels by slowing down its oxidation and generate significant synergistic benefits from assimilating dual nitrogen forms and improving adaptation to low N systems. Deploying BNI-enabled wheat on a significant proportion of current global wheat area (ca. 225 M ha) could be a powerful nature-based solution for reducing N fertilizer use and nitrogen losses while maintaining productivity.

Population growth and climate change present crop researchers and plant breeders with one of the great grand challenges of the 21st century- to productively grow nutritious crops in water-scarce environments (Pimentel et al. 2004). Agriculture currently uses 75 % of the total global consumption of water (Molden 2007). Some of the crop technologies that were able to feed the growing world in the 20th century were highly dependent on inputs including water resources, whose use in agriculture almost treble from the beginning of the 1940s to the end of the century. About a third of the current global population lives in water-stressed locations and this may increase to two thirds within the next 25 years. Consumptive water use (or transpired water) by all food and fodder crops will, therefore, need to increase from its present estimated level (7,000-12,586 km3 year) to be capable of feeding adequately the 9.3 billion population of 2050 (Falkenmark and Rockström 2004). Water use efficiency varies substantially between crops, for example, to produce 1 kg of grain on average requires 900 liters for wheat (Triticum spp.), 1400 liters for maize (Zea mays) and 1900 liters for rice (Oriza sativa) (Pimentel 1997). In addition, there are great prospects for increasing the water use efficiency of specific genotypes within each crop. Water use-efficiency and water productivity are being sought by agricultural researchers worldwide to address the global challenge that especially afflicts the resource poor, in drought-prone environments across the developing world. Under water-scarcity, grain yields of cereals such as wheat are a function of the amount of water used by the