Electrical Physiological Mechanism Of Atrhed In Regulating Root Hair Growth Via Nh₄⁺

The root system is an important organ of plant, in addition to fixing plant, it also canabsorb nutrients from soil and secrete organic matters and interact with some microbe. Thepresence of root hairs further increases the effective surface area. Root hairs growth process isa typical polarity growth, although much researchs have been done, the detailed mechanismand influence factors remains to be further discussed.Nitrogen is one of the most important macroelements needed by plants. Ammonianitrogen and nitrate nitrogen are the main nitrogen forms for roots to absorb. They canprovide nutrition for plants and play an important role in root architecture. AtRHED is aserine/threonine protein kinase. Bioinformatics analysis suggests the protein is a membraneprotein, which contains typical extracellular, transmembrane and intracellular domains. Theformer study of my laboratory found that the AtRHED missing mutants show extreme shortroot hair compared with the wild type. Interestingly, the phenotype of mutants can restorewhen growed in the medium lack of NH4+. It shows that AtRHED and NH4+play a role inregulating root hairs growth in some way at the same time.In this paper, i modified and optimized the method of root hairs protoplasts isolation,and then according to the method of isolating live vacuoles from Arabidopsis thalianamesophyll cells, the vacuoles of Arabidopsis thaliana root hairs cells were successfullyobtained. At the same time, I charactered the method of NH4+current record using patchclamp technique, and then recorded the NH4+current of wild type and mutant in whole-celland whole-vacuole configuration.The results showed that the wild types express less inwardcurrents on the cell membrane and more inward currents on the tonoplast membranecompared to the mutants. On the contrary, the mutants turn out that more inward currentsthrough the membrance go into the cells and less incurrent go into vacuole through the vacuole membrance. It revealed that the different NH4+permeability of cell membrane andtonoplast membrane are the causes of different phenotype between wild type and mutantabout root hairs length.Above all, our results showed that AtRHED participate in the regulation of root hairgrowth through the regulation of the absorption of NH₄⁺and the distribution of NH4+in theroot hair cells.