Tissue-specific down-regulation of LjAMT1;1 compromises nodule function and enhances nodulation in Lotus japonicus

• Published in: Plant molecular biology Vol. 68; no. 6; pp. 585 - 595
• Main Authors: Rogato, Alessandra, D'Apuzzo, Enrica, Barbulova, Ani, Omrane, Selim, Stedel, Catalina, Simon-Rosin, Ulrike, Katinakis, Panagiotis, Flemetakis, Manolis, Udvardi, Michael, Chiurazzi, Maurizio
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.12.2008; Springer Netherlands; Springer Nature B.V
• Subjects: Base Sequence; Biochemistry; Biomedical and Life Sciences; DNA Primers; Down-Regulation; Genetics; In Situ Hybridization; Life Sciences; Loteae - physiology; Nitrogen; Nitrogen Fixation - physiology; Plant biology; Plant Pathology; Plant Proteins - physiology; Plant Sciences; Plants, Genetically Modified; Reverse Transcriptase Polymerase Chain Reaction; Symbiosis; Symbiosis; Nitrogen fixation; Ammonium transport; Nodule
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-008-9394-5

Plant ammonium transporters of the AMT1 family are involved in N-uptake from the soil and ammonium transport, and recycling within the plant. Although AMT1 genes are known to be expressed in nitrogen-fixing nodules of legumes, their precise roles in this specialized organ remain unknown. We have taken a reverse-genetic approach to decipher the physiological role of LjAMT1;1 in Lotus japonicus nodules. LjAMT1;1 is normally expressed in both the infected zone and the vascular tissue of Lotus nodules. Inhibition of LjAMT1;1 gene expression, using an antisense gene construct driven by a leghemoglobin promoter resulted in a substantial reduction of LjAMT1;1 transcript in the infected tissue but not the vascular bundles of transgenic plants. As a result, the nitrogen-fixing activity of nodules was partially impaired and nodule number increased compared to control plants. Expression of LjAMT1;1-GFP fusion protein in plant cells indicated a plasma-membrane location for the LjAMT1;1 protein. Taken together, the results are consistent with a role of LjAMT1;1 in retaining ammonium derived from symbiotic nitrogen fixation in plant cells prior to its assimilation.