Nitrogen Starvation Differentially Influences Transcriptional and Uptake Rate Profiles in Roots of Two Maize Inbred Lines with Different NUE.

Maria Mascia,Davide Sega,Zeno Varanini,Anita Zamboni

doi:10.3390/ijms20194856

Maria Mascia, Davide Sega + Show 2 more

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https://doi.org/10.3390/ijms20194856

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Abstract

Nitrogen use efficiency (NUE) of crops is estimated to be less than 50%, with a strong impact on environment and economy. Genotype-dependent ability to cope with N shortage has been only partially explored in maize and, in this context, the comparison of molecular responses of lines with different NUE is of particular interest in order to dissect the key elements underlying NUE. Changes in root transcriptome and NH4+/NO3− uptake rates during growth (after 1 and 4 days) without N were studied in high (Lo5) and low (T250) NUE maize inbred lines. Results suggests that only a small set of transcripts were commonly modulated in both lines in response to N starvation. However, in both lines, transcripts linked to anthocyanin biosynthesis and lateral root formation were positively affected. On the contrary, those involved in root elongation were downregulated. The main differences between the two lines reside in the ability to modulate the transcripts involved in the transport, distribution and assimilation of mineral nutrients. With regard to N mineral forms, only the Lo5 line responded to N starvation by increasing the NH4+ fluxes as supported by the upregulation of a transcript putatively involved in its transport.

Highlights

Nitrogen (N) is the mineral nutrient required by plants in the largest amount for growth and development
To dissect the root molecular responses to N starvation of the two maize inbred lines, Lo5 and T250, showing different Nitrogen use efficiency (NUE) in field [15,16], we carried out a series of comparison of root genome-wide transcriptional profiles obtained through microarray analysis
Regarding the genotype-dependent transcriptome responses linked to N nutrition, it was reported a description of changes due to low N condition (0.2 mM vs. 2 mM) in two Tibetan wild barley genotypes exhibiting different tolerance to this nutritional stress [21]

Summary

Introduction

Nitrogen (N) is the mineral nutrient required by plants in the largest amount for growth and development. Nitrogen use efficiency (NUE) is a complex trait constituted by two main components, N uptake (NUpE) and N utilization efficiency (NUtE), and involves biochemistry, phenology, architecture and responses to the environment [4,5]. NUE differences were observed in relation to the polymorphism of a NRT1.1B gene encoding a NO3− transporter that is involved in the signaling of the same anion [7]. An increase of yield was observed in the same species in response to the overexpression of OsNRT2.3, a gene encoding an high-affinity NO3−

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