High impact information on NIA1

• The two genes have been mapped using restriction fragment length polymorphisms; gNR2 is close to the previously identified chl-3 locus and is probably identical to it, while gNR1 maps to a new locus (NIA1) on chromosome 1, near gl-2 [1].
• The cytokinin-inducible genes CYCD3 and NIA1 are upregulated constitutively in rpn12a-1, indicating that feedback-inhibitory mechanisms also may be altered. rpn12a-1 seedlings also showed changes in auxin-induced growth responses, further illustrating the close interaction between auxin and cytokinin regulation [2].
• Analysis of three mutants with lesions in the NIA2 NR structural gene showed that one mutant, chl3-1, has a reduced phosphorylation phenotype that is not complemented by a NR deletion mutant [3].
• The overexpression is found only in mutants with reduced NIA2 activity, and disruption of the NIA1 gene alone has no effect on NRT1.1 expression [4].
• The synthetic target peptides were based on sequences from Arabidopsis nitrate reductase (NR2) and the plasma membrane proton pump (AHA2) representing fundamentally different target classes [5].

Biological context of NIA1

• Because the up-regulation of NRT1.1 and NIA1 is observed in N-sufficient NR mutant plants, it cannot be related to a release of the general feedback repression exerted by the N status of the plant [4].
• Deletion analyses of these regions show that 238- and 188-bp 5' flanking regions of the NR1 and NR2, respectively, contain sequences responsive to nitrate induction [6].
• Here we describe promoter analyses of the 5' flanking regions of the Arabidopsis NR genes, NR1 and NR2, with respect to nitrate induction of gene expression [6].
• To investigate the involvement of NR in INF1-induced NO production, NR genes were silenced by virus-induced gene silencing [7].
• These results suggest that NR is involved in INF1-induced NO production, and post-translational modification of NR or availability of substrate NO(2) (-) may be a rate-limiting step of NO production by NR [7].

Anatomical context of NIA1

• In contrast, overexpression of NbNR1 encoding N. benthamiana NR by Agrobacterium-mediated transient expression elevated NO(2) (-)-producing activity nine times over the control; however, INF1-induced NO production in protoplasts overexpressing NbNR1 was comparable with that in control protoplasts [7].

Associations of NIA1 with chemical compounds

• These results show that the NIA1 gene encodes a functional NR protein that contributes to the assimilation of nitrate in Arabidopsis [8].
• Accordingly, nitrite (NO2-) strongly represses NRT1.1 and NIA1 transcript accumulation in the roots [4].

References