Molecular Manipulation of the miR399/ Expression Module Alters the Salt Stress Response of .

In (), the microRNA399 (miR399)/ () expression module is central to the response of to phosphate (PO) stress. In addition, miR399 has been demonstrated to also alter in abundance in response to salt stress. We therefore used a molecular modification approach to alter miR399 abundance to investigate the requirement of altered miR399 abundance in in response to salt stress. The generated transformant lines, and plants, with reduced and elevated miR399 abundance respectively, displayed differences in their phenotypic and physiological response to those of wild-type (Col-0) plants following exposure to a 7-day period of salt stress. However, at the molecular level, elevated miR399 abundance, and therefore, altered target gene expression in salt-stressed Col-0, and plants, resulted in significant changes to the expression level of the two PO transporter genes, () and . Elevated PHT1;4 and PHT1;9 PO transporter levels in salt stressed would enhance PO translocation from the root to the shoot tissue which would supply additional levels of this precious cellular resource that could be utilized by the aerial tissues of salt stressed to either maintain essential biological processes or to mount an adaptive response to salt stress.