Aiming to increase nitrogen use efficiency (NUE) of rice, researchers
shifted their focus unto rice PTR/NRT1 transporters, which are critical for
rice growth and development. OsPTR6, a PTR/NRT1 transporter, was
overexpressed in rice cultivar Nipponbare. Three transgenic lines, named
OE1, OE5 and OE6, were produced and subjected to growth experiments in
different nitrogen treatments.

The results of this study, conducted by researchers from Nanjing
Agricultural University in China, showed that plant height and biomass of
the overexpressing lines were increased, and plant nitrogen accumulation and
glutamine synthetase (GS) activities were enhanced. Overexpression of OsPTR6
also increased expression of the OsATM1 genes. However, NUE decreased at
treatments of high nitrogen.

These data suggest that overexpression of the OsPTR6 gene could increase
rice growth through increasing ammonium transporter expression and glutamine
synthetase activity, however, it also decreases nitrogen use efficiency
during conditions of high ammonium supply.

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