DISCUSSION
Several studies have explored plant responses to P-stress at different
levels, from biochemical and molecular, through physiological to
developmental. However, few of the past studies have taken broad,
integrative approaches encompassing all these levels, and most if not
all of these have focused on annual plant species, especially model
species (Morcuende et al., 2007; Hernandez et al., 2007). Here, we have
focused on long-term effects of P-stress in the important perennial
grass, P. virgatum , or switchgrass, integrating experiments on
plant growth and development with genome-wide analysis of
transcriptional responses and metabolism. While many of the adaptive
responses of switchgrass to P-stress are conserved in annual plant
species that have been studied, some unusual responses were found in
switchgrass, such as storage of significant Pi in shoots of severely
P-stressed plants, which may reflect the perennial nature of this
species. Below, we compare and contrast P-stress responses of
switchgrass with those of other plant species.