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Essay On Pia

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Many reports have clearly demonstrated the roles of phytohormones in Pi signaling pathways (López-Bucio et al., 2005; Nacry et al., 2005). Previous work has shown that Pi starvation in plants caused a reduction in Gibberellic Acid (GA) levels and accumulation of DELLA proteins. DELLA-mediated signaling contributes to certain aspects of Pi-deficiency responses in roots, i.e. suppression of primary root growth and raise of root hairs (C. Jiang, Gao, Liao, Harberd, & Fu, 2007). Auxin is known to control GA-mediated repression of two growth-repressor DELLA proteins known as RGA and GAI (Fu & Harberd, 2003). Furthermore, it was shown that ethylene and strigolactone biosynthesis is induced in response to Pi deficiency (Nagarajan & Smith, 2011). …show more content…

In higher plants, four Pi transporter (Pht) families have been characterized (Pht1-Pht4) (B. Guo et al., 2008; Lin, Lin, & Chiou, 2009; Nussaume et al., 2011; Poirier & Bucher, 2002; Versaw & Harrison, 2002). Many members of the Pht1 family play important roles in Pi acquisition from soil and root-to-shoot translocation of Pi (Nussaume et al., 2011). The single Pht2 family member, Pht2;1, is a low-affinity Pi transporter localized to the chloroplast envelope where it plays an important role in photosynthetic activity (Rausch, Zimmermann, Amrhein, & Bucher, 2004; Versaw & Harrison, 2002). The Pht3 family is comprised of mitochondrial-localized transporters to provide Pi for the oxidative phosphorylation of ADP to ATP (Nakamori et al., 2002; Poirier & Bucher, 2002). Pht4 transporters are low-affinity transporters that localize to plastids and Golgi (B. Guo et al., 2008). The cooperation among the four Pht families allows plants to maintain Pi homeostasis (Figure 3). Regulatory components involved in Pi signaling and Pi homeostasis in plants Plants have evolved to react to fluctuations of Pi levels by means of complex responses that tightly control intercellular Pi levels. These responses are initiated and modulated by elaborate signaling networks that maintain Pi homeostasis via global

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