A holistic view of nitrogen acquisition in plants

Abstract

Nitrogen (N) is the mineral nutrient required in the greatest amount and its availability is a major factor limiting growth and development of plants. As sessile organisms, plants have evolved different strategies to adapt to changes in the availability and distribution of N in soils. These strategies include mechanisms that act at different levels of biological organization from the molecular to the ecosystem level. At the molecular level, plants can adjust their capacity to acquire different forms of N in a range of concentrations by modulating the expression and function of genes in different N uptake systems. Modulation of plant growth and development, most notably changes in the root system architecture, can also greatly impact plant N acquisition in the soil. At the organism and ecosystem levels, plants establish associations with diverse microorganisms to ensure adequate nutrition and N supply. These different adaptive mechanisms have been traditionally discussed separately in the literature. To understand plant N nutrition in the environment, an integrated view of all pathways contributing to plant N acquisition is required. Towards this goal, in this review the different mechanisms that plants utilize to maintain an adequate N supply are summarized and integrated.

Impact of metagenomic DNA extraction procedures on the identifiable endophytic bacterial diversity in Sorghum bicolor (L. Moench)

“…Genera including Pseudomonas, Erwinia, Stenotrophomonas, Paenibacillus, Bacillus and Herbaspirillum have previously been shown to play important and varied roles in plant life (Table 3). For example, representatives of Bacilli, Pseudomonads and Rhizobia species have been shown to produce plant growth promoting hormones (Matiru and Dakota, 2004;Sahu et al, 2012;Reis et al, 2011) and also include numerous diazotrophic bacteria that are able to mineralise atmospheric nitrogen and/or solubilise phosphate compounds, to the benefit of the plant (Reis et al, 2011;Kraiser et al, 2011). Genera with potential plant-growth promoting properties can be targeted and isolated for development of biofertilizer or biocontrol products.…”

“…Beneficial endophytic bacteria -also known as plant growth promoting endophytic bacteria (PGPeB) -enhance the plant's growth and/or its ability to withstand stress (Schenk et al, 2012). They achieve this directly through production of plant-growth inducing phytohormones, such as indole acetic acid (IAA), gibberellins and auxins (Dodd et al, 2010), or indirectly via their varied nutrient-liberating metabolic activities such as nitrogen (N 2 ) fixation, phosphate (P) solubilisation and iron sequestration (Khan et al, 2009;Kraiser et al, 2011;Saha et al, 2012). PGPeB have also been implicated in enhancing the plant's resistance against pathogens through direct induction of the plant's defence system or production of antimicrobial compounds (Heydari and Pessarakli, 2010).…”

Ectopic phytocystatin expression increases nodule numbers and influences the responses of soybean (Glycine max) to nitrogen deficiency

“…Translocation of accumulated nitrogen reserves from older to newer tissues is achieved by the programmed turnover of cellular components, a process in which protein degradation plays a central role (Agren, 1985;McConnaughay and Coleman, 1999;Lemaire et al, 2008;Kraiser et al, 2011). This mechanism becomes systemic under conditions of nitrogen limitation, due to the need to triage constituents, and completion of the life cycle becomes prioritized over vegetative growth (Carter and Knapp, 2000;Tranbarger et al, 2003;Zhao et al, 2005;Hermans et al, 2006).…”

Identification and Functional Characterization an Ortholog of OsENOD93-1 Gene in Wheat Using in-silico Approach

“…Nitrogen (N) is a valuable contributor to total plant biomass and a limiting factor in plant growth and development (Kraiser et al, 2011). It is an essential component of most biological molecules including proteins, enzymes, and metabolic products (Good et al, 2004).…”