Tissue-specific down-regulation of LjAMT1;1 compromises nodule function and enhances nodulation in Lotus japonicus
Tissue-specific down-regulation of LjAMT1;1 compromises nodule function and enhances nodulation in Lotus japonicus
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DOI：
10.1007/s11103-008-9394-5
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发表时间：
2008-12-01
影响因子：
5.1
通讯作者：
Chiurazzi, Maurizio
中科院分区：
文献类型：
--
作者：
Rogato, Alessandra;D'Apuzzo, Enrica;Chiurazzi, Maurizio
AMT 1家族的植物铵转运蛋白参与土壤氮素的吸收、铵的转运和植物体内的再循环。虽然AMT 1基因已知在豆科植物的固氮根瘤中表达，但它们在这个专门器官中的确切作用仍然未知。我们已经采取了反向遗传的方法来破译LjAMT 1;1在百脉根根瘤的生理作用。LjAMT 1;1通常在莲花根瘤的感染区和维管组织中表达。抑制LjAMT 1; 1基因表达，使用由豆血红蛋白启动子驱动的反义基因构建体，导致感染组织中LjAMT 1;1转录物的大幅减少，但转基因植物的维管束中没有。结果，根瘤的固氮活性部分受损，根瘤数量增加，与对照植物相比。LjAMT 1;1-GFP融合蛋白在植物细胞中的表达表明了LjAMT 1;1蛋白的质膜定位。两者合计，结果与LjAMT 1的作用是一致的;1在保留来自共生固氮在植物细胞同化之前的铵。
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.