Os04g0509600

The rice Os04g0509600 was reported as OsAMT1;1 in 2013 by researchers from Canada.

Annotated Information

Figure 1. The relative expression of the OsAMT1;1 gene and plant growth parameters of transgenic and wild-type plants grown in hydroponics..

• Os04g0509600 <=> OsAMT1;1,OsAMT1,AMT1-1,AMT1,OsAMT1-1

Function

• OsAMT1;1 is one of the OsAMT1 family members which contain three genes(OsAMT1;1,OsAMT1;2 and OsAMT1;3).
• OsAMT1;1 has ammonium transporters activity.The amino acid sequences of the OsAMT1;1, OsAMT1;2 and OsAMT1;3 share high sequence similarity to each other and to other AMT1-type ammonium transporters previously identified from other plant species.
• OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions

Phenotypic analysis

• When grown in different NH4+ levels, rice plants at 300 μM delivered the maximum growth in both WT and transgenic plants, indicating that of the concentrations tested it is optimal for rice plant growth and development (Fig. 1B).
• In contrast, 30 μM NH4+ produced nitrogen-deficient symptoms in plants, whereas 3000 μM produced NH4+ toxicity and poor plant growth (Fig. 1B). Hence, 300 μM NH 4+ was set as the optimum nitrogen concentration and also denoted as the control condition.
• In this concentration, the growth performances of WT and transgenic plants were the same (Fig. 1B–F). When grown in 30 μM NH4+ , in general plants performed worse than the controls, showing shorter shoots and lower shoot and root biomass levels (Fig. 1B–F).
• However, under this nitrogen-deficient condition, transgenic plants performed better than WT plants, exhibiting significantly longer shoots and roots, and greater shoot and root biomass (P < 0.05). When grown in high nitrogen, 3000 μM NH 4+ , transgenic and WT plants showed poor growth compared with the control (300 μM), probably due to NH 4+ toxicity. This poor growth included shorter shoots and roots, and lower shoot and root biomass than the controls (Fig. 1C–F).
• However, in the higher NH4+ concentration, the WT performed better than the transgenic lines, which showed severe growth-retarded symptoms due to excessive uptake and accumulation of NH 4+ . In this concentration, WT plants had significantly longer shoots and roots, as well as greater shoot and root biomass than trans- genic lines (P < 0.05; Fig. 1C–F).
• Azygous control plants in which progeny from the transgenic lines did not carry the transgene were identified. Comparison of these plants (L-2 neg. and L-3 neg.) with the WT showed that they all behaved in the same way (Supplementary Fig. S3A–E available at JXB online).
• Root systems of 4-week-old mature plants, grown in different NH 4+ levels, clearly showed that the transgenic lines performed better than the WT at limiting ammonium levels, while the converse was found under toxic levels of ammonium (Fig. 1G).

Expression

• For comparison, the expression of the OsAMT1;1 gene in WT plants grown in 300 μM NH 4+ (optimum concentration) was set as the base value of 1 in both roots and shoots. The relative expression of the OsAMT1;1 gene in transgenic lines was ~10- to 30-fold the expression in the WT, in both roots and shoots.
• In general, plants grown in 3000 μM exhibited the highest expression levels, whereas plants in 30 μM exhibited the lowest expression.
• The expression of plants at 300 μM was intermediate. This indicates that OsAMT1;1 is an NH 4+ -responsive gene. Analysis of relative OsAMT1;1 gene expression throughout the day showed that its expression was greatest from morning to noon, but decreased significantly in the late afternoon and evening. This was an ~8-fold reduction compared with its maximum value at noon.

Figure 3. Intercellular localization of OsAMT1;1 protein..

Subcellular localization

• The intercellular localization of the OsAMT1;1 gene was investigated in onion epidermal cells expressing N-terminal GFP::OsAMT1;1 fusions under the control of the 35S promoter from Cauliflower mosaic virus (CaMV).
• Successfully transformed cells exhibited RFP fused to the plasma membrane in the onion epidermis (Fig. 3A). GFP-dependent fluorescence was also observed in the plasma membrane of onion epidermal cells (Fig. 3B).
• The merged image (Fig. 3C) clearly showed co-localization of RFP and GFP in the plasma membrane; Fig. 3D shows a light micrograph of the transformed onion epidermal cell. These results indicated that the OsAMT1;1 transporter protein is localized in the plasma membrane.

Labs working on this gene

• Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1