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In higher plants, NO3(-) can induce its own uptake and the magnitude of this induction is positively related to the external anion concentration. This phenomenon has been characterized in both herbaceous and woody plants. Here, different adaptation strategies of roots from two maize (Zea mays L., ZmAGOs) inbred lines differing in nitrogen use efficiency (NUE) and exhibiting different timing of induction were discussed by investigating NO3(-) -induced changes in their transcriptome. Lo5 line (high NUE) showing the maximum rate of NO3(-) uptake 4 h after the provision of 200 μmol/L NO3(-) treatment modulated a higher number of transcripts relative to T250 (low NUE) that peaked after 12 h. The two inbred lines share only 368 transcripts that are modulated by the treatment with NO3(-) and behaved differently when transcripts involved in anion uptake and assimilation were analyzed. T250 line responded to the NO3(-) induction modulating this group of genes as reported for several plant species. On the contrary, the Lo5 line did not exhibit during the induction changes in this set of genes. Obtained data suggest the importance of exploring the physiological and molecular variations among different maize genotypes in response to environmental clues like NO3(-) provision, in order to understand mechanisms underlying NUE. more...

The induction, i.e., the rapid increase of nitrate (NO3–) uptake following the exposure of roots to the anion, was studied integrating physiological and molecular levels in maize roots. Responses to NO3– treatment were characterized in terms of changes in NO3– uptake rate and plasma membrane (PM) H+-ATPase activity and related to transcriptional and protein profiles of NRT2, NRT3, and PM H+-ATPase gene families. The behavior of transcripts and proteins of ZmNRT2s and ZmNRT3s suggested that the regulation of the activity of inducible high-affinity transport system (iHATS) is mainly based on the transcriptional/translational modulation of the accessory protein ZmNRT3.1A. Furthermore, ZmNRT2.1 and ZmNRT3.1A appear to be associated in a ∼150 kDa oligomer. The expression trend during the induction of the 11 identified PM H+-ATPase transcripts indicates that those mainly involved in the response to NO3– treatment are ZmHA2 and ZmHA4. Yet, partial correlation between the gene expression, protein levels and enzyme activity suggests an involvement of post-transcriptional and post-translational mechanisms of regulation. A non-denaturing Deriphat-PAGE approach allowed demonstrating for the first time that PM H+-ATPase can occur in vivo as hexameric complex together with the already described monomeric and dimeric forms. more...

In higher plants, NO3(-) can induce its own uptake and the magnitude of this induction is positively related to the external anion concentration. This phenomenon has been characterized in both herbaceous and woody plants. Here, different adaptation strategies of roots from two maize (Zea mays L., ZmAGOs) inbred lines differing in nitrogen use efficiency (NUE) and exhibiting different timing of induction were discussed by investigating NO3(-) -induced changes in their transcriptome. Lo5 line (high NUE) showing the maximum rate of NO3(-) uptake 4 h after the provision of 200 μmol/L NO3(-) treatment modulated a higher number of transcripts relative to T250 (low NUE) that peaked after 12 h. The two inbred lines share only 368 transcripts that are modulated by the treatment with NO3(-) and behaved differently when transcripts involved in anion uptake and assimilation were analyzed. T250 line responded to the NO3(-) induction modulating this group of genes as reported for several plant species. On the contrary, the Lo5 line did not exhibit during the induction changes in this set of genes. Obtained data suggest the importance of exploring the physiological and molecular variations among different maize genotypes in response to environmental clues like NO3(-) provision, in order to understand mechanisms underlying NUE. more...

The phenomenon of NO3- induction in plant roots has been characterised both in herbaceous and woody plants. Grapevine (Vitis vinifera L.) plants, hydroponically grown, showed an increase in NO3- uptake rate in response to anion treatment for different periods in the nutrient solution after 1 week of NO3- deprivation. The expression profile of the two high-affinity NO3- transporters VvNRT2.4A and VvNRT2.4B, and the gene encoding the accessory protein VvNAR2.2 exhibits a similar trend to that of the anion uptake. The induction, also involving the increase in activity and protein levels of plasma membrane H+-ATPase, is correlated with the expression profile of two (VvHA2 and VvHA4) out of eight putative plasma membrane H+-ATPase genes identified in grapevine genome. more...

The phenomenon of NO3– induction in plant roots has been characterised both in herbaceous and woody plants. Grapevine (Vitis vinifera L.) plants, hydroponically grown, showed an increase in NO3– uptake rate in response to anion treatment for different periods in the nutrient solution after 1 week of NO3– deprivation. The expression profile of the two high-affinity NO3– transporters VvNRT2.4A and VvNRT2.4B, and the gene encoding the accessory protein VvNAR2.2 exhibits a similar trend to that of the anion uptake. The induction, also involving the increase in activity and protein levels of plasma membrane H+-ATPase, is correlated with the expression profile of two (VvHA2 and VvHA4) out of eight putative plasma membrane H+-ATPase genes identified in grapevine genome. more...