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

• Published in: Proceedings of the National Academy of Sciences - PNAS 2021-08, Vol.118 (35), p.1-9
• Main Authors: Subbarao, Guntur V., Kishii, Masahiro, Bozal-Leorri, Adrian, Ortiz-Monasterio, Ivan, Gao, Xiang, Ibba, Maria Itria, Karwat, Hannes, Gonzalez-Moro, M. B., Gonzalez-Murua, Carmen, Yoshihashi, Tadashi, Tobita, Satoshi, Kommerell, Victor, Braun, Hans-Joachim, Iwanaga, Masa
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Ammonium; Biological Sciences; Chromosomes; Chromosomes, Plant - genetics; Crop production; Crops, Agricultural - genetics; Crops, Agricultural - growth & development; Crops, Agricultural - metabolism; Cultivars; Glutamate-ammonia ligase; Glutamine; Grain; Grasses; Intensive farming; Leymus racemosus; Mineralization; Nitrate reductase; Nitrates; Nitrification; Nitrogen; Nitrogen - metabolism; Nitrous oxide; Nutrition; Organic matter; Organic soils; Plant breeding; Plant Proteins - genetics; Plant Proteins - metabolism; Plant roots; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Reductases; Soil organic matter; Soils; Triticum - genetics; Triticum - growth & development; Triticum - metabolism; Wheat
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2106595118

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#3Nsb” (Lr#n), which can be transferred to wheat as T3BL.3NsbS (denoted Lr#n-SA), where 3BS arm of chromosome 3B of wheat was replaced by 3NsbS of L. racemosus. We successfully introduced T3BL.3NsbS 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.3NsbS 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.