Phosphorus is one of the macronutrients essential for plant growth and development, as well as crop productivity. Many soils around the world are deficient in phosphate (Pi) that plants can utilize. To cope with the stress of Pi starvation, plants have evolved many adaptive strategies, such as changes of root architecture and enhanced Pi acquisition form soil. To understand molecular mechanism underlying Pi starvation stress signaling, we characterized the activation-tagged mutant showing altered responses to Pi deficiency compared to wild type Arabidopsis and named hsp3 (hypersensitive to Pi starvation3). hsp3 mutant exhibits enhanced phosphate transporter activity, resulting in higher Pi content than wild type. However, in root architectural change under Pi starvation, hsp3 shows hyposensitive responses than wild type, such as longer primary root elongation, lower lateral root density. Histochemical analysis using hsp3 mutant expressing auxin-responsive DR5::GUS reporter gene, indicated that auxin allocation from primary to lateral roots under Pi starvation is aborted in hsp3 mutant. Molecular genetic analysis of hsp3 mutant revealed that the mutant phenotype is caused by the lesion in ENHANCED SILENCING PHENOTYPE4 (ESP4) gene whose function is proposed in mRNA 3’ end processing. Here, we propose that mRNA processing plays a crucial role in Pi homeostasis in Arabidopsis.

In order to adapt to various environmental stresses, plants have employed diverse regulatory mechanisms of gene expression. Epigenetic changes, such as DNA methylation and histone modifications play an important role in gene expression regulation under stress condition. It has been known that some of epigenetic modifications are stably inherited after mitotic and meiotic cell divisions, which is known as stress memory. To understand molecular mechanisms underlying stress memory mediated by epigenetic modifications, we developed Arabidopsis suspension-cultured cell lines adapted to high salt by stepwise increases in the NaCl concentration up to 120 mM. Adapted cell line to 120 mM NaCl, named A120, exhibited enhanced salt tolerance compared to unadapted control cells (A0). Moreover, the salt tolerance of A120 cell line was stably maintained even in the absence of added NaCl, indicating that the salt tolerance of A120 cell line was memorized even after the stress is relieved. By using salt adapted and stress memorized cell lines, we intend to analyze the changes of DNA methylation, histone modification, transcriptome, and proteome to understand molecular mechanisms underlying stress adaptation as well as stress memory in plants.

In these experiments Gamiojeoksan remnant components were analyzed to recycle this medicinal herb remnant fertilizers. The basic growth of Korean mint by application of Gamiojeoksan remnants were higher than control. As the amount of fertilizers were increased, plant height, stem diameter, number of leaves and number of branches were increased. The growth and yield were the highest in the treatment of 30 g/pot. Weight of whole plant of Korean mint has a tendency to be heavy in application of herbs remnant than that of control.