Developmental and physiological responses of Brachypodium distachyon to fluctuating nitrogen availability

Abstract

The Nitrogen Use Efficiency (NUE) of grain cereals depends on nitrate (NO 3 − ) uptake from the soil, translocation to the aerial parts, nitrogen (N) assimilation and remobilization to the grains. Brachypodium distachyon has been proposed as a model species to identify the molecular players and mechanisms that affects these processes, for the improvement of temperate C3 cereals. We report on the developmental, physiological and grain-characteristic responses of the Bd21-3 accession of Brachypodium to variations in NO 3 − availability. As previously described in wheat and barley, we show that vegetative growth, shoot/root ratio, tiller formation, spike development, tissue NO 3 − and N contents, grain number per plant, grain yield and grain N content are sensitive to pre- and/or post-anthesis NO 3 − supply. We subsequently described constitutive and NO 3 − -inducible components of both High and Low Affinity Transport Systems (HATS and LATS) for root NO 3 − uptake, and BdNRT2/3 candidate genes potentially involved in the HATS. Taken together, our data validate Brachypodium Bd21-3 as a model to decipher cereal N nutrition. Apparent specificities such as high grain N content, strong post-anthesis NO 3 − uptake and efficient constitutive HATS, further identify Brachypodium as a direct source of knowledge for crop improvement.

N-dependent dynamics of root growth and nitrate and ammonium uptake are altered by the bacterium Herbaspirillum seropedicae in the cereal model Brachypodium distachyon

“…We found that B. distachyon grown in high N medium had greater leaf area and shoot biomass, and comparable root length to B. distachyon grown at lower N. This fits with expected plant behavior under N limitation ( Cambui et al , 2011 ; David et al , 2019 ). The resource allocation in the case of the high 5 mM NH 4 NO 3 was greater towards shoots, compared with in the case of 0.5 mM NH 4 NO 3 , which was directed to the root system ( Fig.…”

“…Enlargement of the EcoFAB-N to 4 ml from 2.8 ml ( Sasse et al , 2019 ) allowed maintenance of N within physiological levels ( Fig. 2A ) ( David et al , 2019 ), and relieved the sharp depletion at high (2.5 mM NH 4 NO 3 ) and low N (0.25 mM NH 4 NO 3 ) ( Supplementary Fig. S1 ) in the original 2.8 ml chamber, which led to large variability in the nutrient conditions, particularly as plants became larger (20 DAT).…”

Experimental system and image analysis software for high throughput phenotyping of mycorrhizal growth response inBrachypodium distachyon

“…Since N is a diffusible nutrient, part of the N can diffuse out of the HC and be accessible to plant roots. In order to limit this effect, we made sure that the total quantity of N introduced in the HC corresponds to the reported need for B. distachyon optimal growth (David et al ., 2019). As P is not diffusible and would thus not leach out the HC, it was put in excess.…”

Signaling Responses to N Starvation: Focusing on Wheat and Filling the Putative Gaps With Findings Obtained in Other Plants. A Review

“…BdNRT2 gene expression is also governed by both internal and external N status (Wang et al, 2019a). BdNRT2/3 genes are potentially involved in HATS for root NO 3 − uptake in Brachypodium distachyon (David et al, 2019). In the bdnrt2.1 mutant, HATS have been shown to be reduced by 30% (Wang et al, 2019a).…”