Figure 4.

Figure showing the regulation of L-proline metabolism during the course of phosphate starvation (Pi) and osmotic stressed conditions. During the course of osmotic stress, L-proline accumulation occurs and structured by the stimulation of P5CS1 and suppression of PDH1 genes, correspondingly. Activation of P5CS1 gene is regulated by ABA signals, probably completed by the ABRE cis acting motif in the promoter. Phosphate starvation stimulated PHR1 and PHL1, which induces by P5CS1 via binding to its P1BS motif. Similarly, PDH2 is also stimulates by PHR1 and PHL1 and Pi scarcity. During phosphate starvation, NCED3 also induced which can increase ABA levels. ABA signals control plant growth and activates several stress-associated genes, comprising PHL1 and P5CS1.