N-dependent dynamics of root growth and nitrate and ammonium uptake are altered by the bacterium Herbaspirillum seropedicae in the cereal model Brachypodium distachyon. (5th May 2022)

• Record Type: Journal Article
• Authors: Kuang, Weiqi; Sanow, Stefan; Kelm, Jana M; Müller Linow, Mark; Andeer, Peter; Kohlheyer, Dietrich; Northen, Trent; Vogel, John P; Watt, Michelle; Arsova, Borjana
• Editors: Janni, Michela
• Is Part Of: Journal of experimental botany. Volume 73:Number 15(2022)
• Page Start: 5306
• Page End: 5321
• Publication Date: 2022-05-05
• Subjects: Agriculture -- Brachypodium -- cereals -- crop productivity -- EcoFAB -- Herbaspirillum seropedicae -- N fixation -- nitrogen -- non-invasive phenotyping -- plant-growth promoting rhizobacteria -- wheat; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erac184
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: Nitrogen (N) fixation in cereals by root-associated bacteria is a promising solution for reducing use of chemical N fertilizers in agriculture. However, plant and bacterial responses are unpredictable across environments. We hypothesized that cereal responses to N-fixing bacteria are dynamic, depending on N supply and time. To quantify the dynamics, a gnotobiotic, fabricated ecosystem (EcoFAB) was adapted to analyse N mass balance, to image shoot and root growth, and to measure gene expression of Brachypodium distachyon inoculated with the N-fixing bacterium Herbaspirillum seropedicae . Phenotyping throughput of EcoFAB-N was 25–30 plants h −1 with open software and imaging systems. Herbaspirillum seropedicae inoculation of B. distachyon shifted root and shoot growth, nitrate versus ammonium uptake, and gene expression with time; directions and magnitude depended on N availability. Primary roots were longer and root hairs shorter regardless of N, with stronger changes at low N. At higher N, H. seropedicae provided 11% of the total plant N that came from sources other than the seed or the nutrient solution. The time-resolved phenotypic and molecular data point to distinct modes of action: at 5 mM NH4 NO3 the benefit appears through N fixation, while at 0.5 mM NH4 NO3 the mechanism appears to be plant physiological, with H. seropedicae promoting uptake of N from the root medium.Future work could fine-tune plant and root-associated microorganisms to growth and nutrient dynamics. Abstract : The nitrogen-fixing bacterium Herbaspirillum seropedicae altered growth, nitrate or ammonium uptake, and gene expression of Brachypodium distachyon dynamically in specialized, fabricated ecosystems. Nitrogen fertilization and time were the most important variables.