Cell division activity determines the magnitude of phosphate starvation responses in Arabidopsis

Abstract

SummaryPhosphate (P i ) is a major limiting factor for plant growth. Plants respond to limiting P i supplies by inducing a suite of adaptive responses comprising altered growth behaviour, enhanced P i acquisition and reduced P i demand that together define a distinct physiological state. In P i -starved plants, continued root growth is required for P i acquisition from new sources, yet meristem activity consumes P i . Therefore, we analysed the relationship between organ growth, phosphate starvation-responsive (PSR) gene expression and P i content in Arabidopsis thaliana under growth-promoting or inhibitory conditions. Induction of PSR gene expression after transfer of plants to P i -depleted conditions quantitatively reflects prior levels of P i acquisition, and hence is sensitive to the balance of P i supply and demand. When plants are P i -starved, enhanced root or shoot growth exacerbates, whereas growth inhibition suppresses, P i starvation responses, suggesting that the magnitude of organ growth activity specifies the level of P i demand. Inhibition of cell-cycle activity, but not of cell expansion or cell growth, reduces P i starvation-responsive gene expression. Thus, the level of cell-cycle activity specifies the magnitude of P i demand in P i -starved plants. We propose that cell-cycle activity is the ultimate arbiter for P i demand in growing organs, and that other factors that influence levels of PSR gene expression do so by affecting growth through modulation of meristem activity.

Characterization of the PHO1 Gene Family and the Responses to Phosphate Deficiency of Physcomitrella patens

“…5B) with similar data obtained for Arabidopsis roots (Lai et al, 2007). Whereas a 45% and 70% decrease in Pi content was observed for Arabidopsis roots 2 and 4 d after a shift to Pi-depleted medium, respectively (Lai et al, 2007), a similar decrease in Pi concentrations for P. patens protonemata was obtained only after 4 and 9 d of Pi starvation (Fig. 4B).…”

“…Addition of cytokinin to Pi-deficient rice or Arabidopsis has been shown to attenuate expression of genes that are specifically up-regulated by Pi deficiency (Martin et al, 2000;Hou et al, 2005;Kobayashi et al, 2006;Lai et al, 2007). To reveal whether a similar mechanism exists in P. patens, protonemata grown for 14 d in Pi-deficient medium were transferred to Pideficient medium supplemented with the cytokinin 6-benzylaminopurine for up to 2 d (Fig.…”

The Dual-Targeted Purple Acid Phosphatase Isozyme AtPAP26 Is Essential for Efficient Acclimation of Arabidopsis to Nutritional Phosphate Deprivation

“…PSI gene expression is influenced by sugar levels (Karthikeyan et al, 2006), while exogenous Suc may exacerbate Pi starvation through increased cell proliferation signaling (Lai et al, 2007). As plant cultivation under sterile conditions in the presence of exogenous Suc may generate phenotypes not seen under more physiologically relevant conditions we examined whether soil-grown atpap26 plants displayed any phenotype.…”

Relationships between Growth, Growth Response to Nutrient Supply, and Ion Content Using a Recombinant Inbred Line Population in Arabidopsis1[W][OA]

“…In addition, Sulpice et al (2009) associated differences in growth with starch content using a set of Arabidopsis accessions. Compiling the importance of ions in the process of cell division (Lai et al, 2007;Sano et al, 2007) or cell expansion (Philippar et al, 1999;Elumalai et al, 2002), ionomics appears to be a major unexplored field for understanding growth.…”