Metabolism Plasticity on Account of Aspartate aminotransferase 10 Promotes Poplar Growth under Altered Nitrogen Regimes

Improving poplar productivity across a wide spectrum
of nitrogen
conditions is a primary objective in poplar breeding. In this research,
we engineered transgenic poplars to overexpress the aspartate
aminotransferase 10 (AspAT10) gene. The
results showed that these transgenic plantlets significantly outperformed
the wild-type control in terms of growth under both nitrogen-poor
and nitrogen-rich conditions, exhibiting increased biomass, height,
and root development. This improvement was linked to changes in internal
nitrogen pools (including NO3–, NH4+, and total free amino acids) and sugar content.
In line with the metabolic results, notable alterations in genes related
to nitrogen and carbon metabolism as well as hormone signaling pathways
were identified. Our findings highlight the versatile role of AspAT10 in regulating poplar’s adaptation to variable
nitrogen availability, attributed to the reversible nature of its
catalytic reaction, which allows for the flexible reprogramming of
nitrogen and carbon metabolism to align nitrogen supply with plant
demand.