Abstract: We investigated the short-term
response of poplar roots to low and high nitrogen
availability in order to elucidate the mechanisms
involved in nutrient acquisition. After 28 days of
fertilization with low versus high ammonium
nitrate, an increase in aboveground biomass was
observed accompanied by a decrease in root
biomass, reducing the root: shoot ratio after 28
days. These changes in biomass allocation were
accompanied by changes in root architecture
and altered gene expression. The gene
expression response was evaluated after 7 days
using a custom cDNA micrarray following
transfer to low and high nitrogen supply. We
found that 56 sequences were differentially
expressed in poplar roots. Many of these 56
genes could be associated with putative roles in
development or response to biotic and abiotic
stress. A time course analysis of selected cell
wall-related genes by RT-qPCR confirmed the
expression patterns obtained by microarray and
also showed the timing of this differential
response. Our results show that patterns of
transcript accumulation in roots of poplars are
influenced by nitrogen supply, providing
evidence of unique nitrogen-adaptative
mechanisms.