Su-Mei LI Bao-Zhen LI Wei-Ming SHI. Expression Patterns of Nine Ammonium Transporters in Rice in Response to N Status. Pedosphere 2012 22 (6): 860–869.

Abstract

Nitrogen use efficiency (NUE) was very low in China and a loss of as much as 70% of the applied nitrogen fertilizers was reported in high-yielding rice fields. In order to investigate the molecular basis of high-affinity ammonium transport or uptake into rice (Oryza sativa L.) we analyzed the expression profiles of nine ammonium transporters (AMT) three each of OsAMT1 OsAMT2 and OsAMT3 at two different N requirement stages (young seedling stage and tillering stage) of rice growth as well as the changes in these expression patterns according to external N status using real-time reverse transcription polymerase chain reaction (RT-PCR). The results suggested that the nine OsAMT genes were expressed in different organs of rice plants including mature roots new roots stems old leaves and new leaves and that the expression patterns were organ specific and independent of the positions of the corresponding proteins in the phylogenetic tree. OsAMT1; 1 3;2 and 3;3 were expressed in the roots and shoots primarily old leavesOsAMT1;2 and 1;3 mainly in the roots and OsAMT2;1 2;2 2;3 and 3;1 mainly in the shoots primarily in new leaves and relatively more in the stems than other genes. The expression patterns at the two different N requirement stages were the same; however at the tillering stage with greater N requirements the OsAMTstranscript levels were greater than those at the young seedling stage with low N requirements. N starvation for 48 h up-regulated OsAMT1;1 1;2 3;1 3;2 3;3 and down-regulated OsAMT1;3 mRNA abundance. Following N starvation NH₄⁺ and NH₄NO₃ re-supply down-regulated OsAMT1;2 and 3;3 and up-regulatedOsAMT1;3 whereas NO₃⁻ re-supply down-regulated OsAMT1;1 and 1;2. These suggested that the organ-specific expression pattern of OsAMT could be regulated by N requirement and external N status.