Poster: Late and Moved Abstracts

Abs # 1411: Study of the root-dominant NRT1 homologs in Arabidopsis

Presenter:	Wang, Ya-yun , ywang308@imb.sinica.edu.tw
Authors	Wang, Ya-yun  (A)   Chiu, Chi-chou  (A)   Tsay, Yi-fang  (A)
Affiliations:	(A): Institute of Molecular Biology

Nitrate is the most important nitrogen source for plant growing in aerobic soil. Plants acquire nitrate from soil solution by the transporters on the plasma membrane of epidermal and cortical cells of the roots. Once inside, the nitrate can be assimilated right away in the root tissue, or transported upwards to the shoot through the xylem. The excess of nitrate will be stored in the vacuole for further use. In plants, nitrate transporters belong to two different families, NRT1 and NRT2. There are 53 homologs in NRT1 family. RT-PCR analyses have shown that they have differential expression pattern in different tissues. For example, some of the homologs only express in root, and some of them are shoot-specific expressed. This result indicates that the 53 homologs may have different physiological roles in nitrate transport in plants. Our study will focus on the nitrate uptake by root. Two root-specific expressed homologs, At1g18880 and At5g62680, will be analyzed the possible functions in nitrate transport. The basic characterizations of these two genes will be assayed in wild-type plant, including the expression pattern in three media with different nitrogen source and whether their expression is induced by nitrate. For functional analysis, the Xenopus oocyte expression system is used to test their nitrate uptake ability. We also screened the knockout plants of these two homologs. After doing these analyses, we hope we could understand more about the regulation of the nitrate transport in plants.