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Nitrogen transport in xylem of soybean plant supplied with15NO3-
| Content Provider | Scilit |
|---|---|
| Author | Ohyama, Takuji Kato, Naoki Saito, Keiko |
| Copyright Year | 1989 |
| Abstract | Recently, the ureides have been recognized as the main transport form of fixed N from soybean nodules. On the other hand, it was suggested that a part of $NO_{3} ^{-}$ absorbed from soybean roots was translocated to the shoots without undergoing any modification, or was exported to the shoots in the form of Asn and other amino acids after reduction and assimilation in the roots (McClure and Israel 1979; Ohyama and Kumazawa 1979; Ohyama 1984). However, information about the processes of $NO_{3} ^{-}$ transport, storage, and assimilation in soybean roots is limited. Two distinct processes have been proposed for the $NO_{3} ^{-}$ transport from soybean roots. When$ $^{15}$NO_{3} ^{-}$ was administered to the intact soybean plants, it was observed that some part of $NO_{3} ^{-}$ was very rapidly assimilated or transported after absorption, whereas, another part was temporarily stored in the roots and slowly released to the shoots when the plants were transferred to the non-labeled conditions (Ohyama 1984). This result may suggest that a part of $NO_{3} ^{-}$ was directly transported after absorption, and the other was once incorporated into a large storage pool of $NO_{3} ^{-}$ (probably vacuoles) and subsequently $NO_{3} ^{-}$ was released to the xylem at a constant rate. The Asn assimilation and transport processes in soybean roots seem to be more complicated. In previous studies, it was observed that the Asn concentration was relatively low in the nodulated soybean roots cultivated in N-free medium, but that the level was markedly increased at 24 h after $NO_{3} ^{-}$ administration (Ohyama et al. 1989a). This may indicate a large temporary storage pool of Asn in the roots is formed along with the $NO_{3} ^{-}$ absorption. On the other hand, some part of $NO_{3} ^{-}$ was found to be once incorporated into protein in the roots. It is suggested that the Asn formed by protein degradation is transported to the shoots (Ohyama 1983, 1984). In this report, the transport of N originating from the absorbed $NO_{3} ^{-}$ was studied by analyzing the xylem exudate collected from decapitated soybean plants at the time when$ $^{15}$NO_{3} ^{-}$ was supplied in the medium. |
| Related Links | http://www.tandfonline.com/doi/pdf/10.1080/00380768.1989.10434744?needAccess=true |
| Ending Page | 137 |
| Page Count | 7 |
| Starting Page | 131 |
| ISSN | 00380768 |
| e-ISSN | 17470765 |
| DOI | 10.1080/00380768.1989.10434744 |
| Journal | Soil Science and Plant Nutrition |
| Issue Number | 1 |
| Volume Number | 35 |
| Language | English |
| Publisher | Informa UK Limited |
| Publisher Date | 1989-03-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Soil Science and Plant Nutrition Plant Sciences Asparagine Nitrate Soybean Xylem Exudate |
| Content Type | Text |
| Resource Type | Article |
| Subject | Soil Science Plant Science |
