Expression of a putative high-affinity NO3- transporter and of an H+-ATPase in relation to whole plant nitrate transport physiology in two maize genotypes differently responsive to low nitrogen availability

Abstract

Two maize genotypes differently responsive to nitrogen availability were characterized for their efficiency in nitrate accumulation via both the LATS (Low-Affinity Transport System) and HATS (High-Affinity Transport System) nitrate uptake systems. In addition, a full-length cDNA encoding a putative high-affinity nitrate transporter (ZmNrt2.1) was isolated and its expression evaluated in both the roots and leaves of the two maize genotypes, together with the expression of a maize H(+)-ATPase isoform (Mha1). The data showed the importance of the iHATS (Inducible High-Affinity System) system efficiency as a physiological marker of adaptation to low input and suggested that the transcript accumulation of ZmNrt2.1 might be a key step for the regulation of iHATS. However, ZmNrt2.1 transcription cannot account for the differences found between the two hybrids in terms of the activity of their respective iHATS and, as a consequence, of their adaptation to low input. Therefore, the involvement of some other transporter(s) or of some post-transcriptional/post-translational mechanism of regulation affecting the efficiency of iHATS may be hypothesized. In addition, the data suggest that the transcription of the Mha1 gene may also be involved in the global efficiency of the iHATS system.

Humic substances stimulate maize nitrogen assimilation and amino acid metabolism at physiological and molecular level

“…accumulation of the gene encoding a NADH-NR [59] showed a significant increase after the treatment with 1 mg C L −1 HS in leaves of N-supplied plants, with respect to that detected in leaves of +N control plants (Figure 8). Conversely, no NR transcript accumulation was observed in the leaves of N-deprived plants of either HS-treated or control seedlings.…”

“…To determine the expression level of NR (NCBI accession number M27821), AS (NCBI accession number X82849), MDH (NCBI accession number T27564), CS (NCBI accession number W49861) and IDH (NCBI accession number W21690), semi-quantitative RT-PCR experiments with specific primers were performed as described earlier [59]. Genes analyzed and relative primers are listed in Table 1.…”

Serial Analysis of Gene Expression Study of a Hybrid Rice Strain (LYP9) and Its Parental Cultivars

“…Examples are several upregulated genes identified as associated to root hair initiation, such as expansion genes, originally demonstrated in Arabidopsis (Cho and Cosgrove, 2002), and cytoskeleton components, crucial for root hair tip growth (Mathur et al, 2003). Other categorized upregulated genes have been indicated playing roles in nitrogen uptake, including ammonium transporters (Lin et al, 2000;Quaggiotti et al, 2003;Suenaga et al, 2003), carbonic anhydrases (Galvez et al, 2000;Buvana and Kannaiyan, 2002), and Rubisco activase (Okubara et al, 1999).…”

The Role of Plants in the Effects of Global Change on Nutrient Availability and Stoichiometry in the Plant-Soil System

“…Plants also have a notable phenotypic plasticity for adapting to changes in N supply. For example, when the availability of N becomes limiting, high-affinity nitrate and ammonium transport systems are up-regulated and lateral root growth is stimulated (Quaggiotti et al, 2003;Remans et al, 2006;Engineer and Kranz, 2007;Krapp et al, 2011). About 3,000 genes in Medicago truncatula are upregulated under N starvation (Ruffel et al, 2008), and the main enzymes of the N cycle (nitrite and nitrate reductases, Gln synthetase and dehydrogenase) are very sensitive to N supply (Horchani et al, 2010), indicating the importance that N uptake has for plants.…”