Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Active nitrifiers and rapid nitrification are major contributing factors to nitrogen losses in global wheat production. Suppressing nitrifier activity is an effective strategy to limit N losses from agriculture. Production and release of nitrification inhibitors from plant roots is termed biological nitrification inhibition (BNI). Here, we report the discovery of a chromosome region that controls BNI production in wheat grass Leymus racemosus (Lam.) Tzvelev, located on the short arm of the Lr#3Ns(b) (Lr#n), which can be transferred to wheat as T3BL.3Ns(b)S (denoted Lr#n-SA), where 3BS arm of chromosome 3B of wheat was replaced by 3Ns(b)S of L. racemosus. We successfully introduced T3BL.3Ns(b)S into the wheat cultivar Chinese Spring (CS-Lr#n-SA, referred to as BNI-CS), which resulted in the doubling of its BNI capacity. T3BL.3Ns(b)S from BNI-CS was then transferred to several elite high-yielding hexaploid wheat cultivars, leading to near doubling of BNI production in BNI-MUNAL and BNI-ROELFS. Laboratory incubation studies with root-zone soil from field-grown BNI-MUNAL confirmed BNI trait expression, evident from suppression of soil nitrifier activity, reduced nitrification potential, and N2O emissions. Changes in N metabolism included reductions in both leaf nitrate, nitrate reductase activity, and enhanced glutamine synthetase activity, indicating a shift toward ammonium nutrition. Nitrogen uptake from soil organic matter mineralization improved under low N conditions. Biomass production, grain yields, and N uptake were significantly higher in BNI-MUNAL across N treatments. Grain protein levels and breadmaking attributes were not negatively impacted. Wide use of BNI functions in wheat breeding may combat nitrification in high N input-intensive farming but also can improve adaptation to low N input marginal areas.

Automated summary

Active nitrifiers and rapid nitrification are major contributors to nitrogen losses in global wheat production. Suppressing nitrifier activity by introducing biological nitrification inhibition (BNI) from Leymus racemosus to wheat can effectively reduce soil nitrifier activity, decrease nitrification potential, and improve nitrogen uptake efficiency. This innovative approach has the potential to enhance nitrogen use efficiency, biomass production, and grain yields in wheat cultivation.