Effects of osmotic and salinity stress on epigenetic marks on gl2, a gene involved in epidermal root differentiation and root hair development in Arabidopsis thaliana

IUSEM NORBERTO DANIEL; BEYRNE, CECILIA; GONZÁLEZ RODRIGO MATIAS

Buenos Aires

Congreso; SAIB 2017 (dentro de Reunión Conjunta de Sociedades de Biociencias); 2017

SAIB

In plants, root epidermal cells are differentiated in two cell types:trichoblast cells and atrichoblast cells. The first one produces roothairs, a long and thin structure involved in absorption of waterand nutrients from soil. Gl2 is a crucial gene determining the fateof root epidermal cells. Gl2 is expressed in non-hair cells, whereit inhibits the expression of genes that promote root hair developmentand elongation (i.e. RHD6, RSL4). On the other hand, it isknown that epigenetic marks arisen by cytosine methylation andhistone methylation or acetylation are stable but can be modifiedby environmental factors. The aim of this work is to determine ifchanges in soil conditions i.e. saline or osmotic stress are able tomodify epigenetic marks on Gl2. These marks might in turn bringabout changes in the expression of this gene thereby regulating thepathway responsible for length and/or density in root hairs. For thatpurpose, plants were grown on plates containing half-strength MSmedium for three weeks. One group was supplemented with 20 mMNaCl and the other with 50 mM mannitol. The control group wasgrown on half-strength MS medium only. Roots were then cut off andimmediately frozen in liquid nitrogen. DNA was isolated following astandard protocol and then subjected to bisulfite treatment, whichconverts unmethylated cytosines into uracil, whereas methylatedcytosines remain unchanged. We found that under 20 mM NaCl,cytosine methylation increases 10% over control methylation levels(51% vs. 41%, p=0.0874) in the gene body of Gl2. In addition, themannitol treatment caused no significative changes in methylationlevels. Overall, these findings indicate that high salinity in soil causesan increment in DNA methylation on the Gl2 gene body, probablyincreasing its expression as usually occurs in plant genes, resultingin inhibition of root hair development.