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.

BEYRNE, CECILIA CARMEN; IUSEM, NORBERTO DANIEL; GONZÁLEZ, RODRIGO MATÍAS

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAIC, SAIB, SAI, SAFE, SAH, SAP, SABiología, SAFIS, SAA y SABiofísica

In plants, root epidermal cells are differentiated in two cell types: trichoblast cells and atrichoblast cells. The first one produces root hairs, a long and thin structure involved in absorption of water and nutrients from soil. Gl2 is a crucial gene determining the fate of root epidermal cells. Gl2 is expressed in non-hair cells, where it inhibits the expression of genes that promote root hair development and elongation (i.e. RHD6, RSL4). On the other hand, it is known that epigenetic marks arisen by cytosine methylation and histone methylation or acetylation are stable but can be modified by environmental factors. The aim of this work is to determine if changes in soil conditions i.e. saline or osmotic stress are able to modify epigenetic marks on Gl2. These marks might in turn bring about changes in the expression of this gene thereby regulating the pathway responsible for length and/or density in root hairs. For that purpose, plants were grown on plates containing half-strength MS medium for three weeks. One group was supplemented with 20 mM NaCl and the other with 50 mM mannitol. The control group was grown on half-strength MS medium only. Roots were then cut off and immediately frozen in liquid nitrogen. DNA was isolated following a standard protocol and then subjected to bisulfite treatment, which converts unmethylated cytosines into uracil, whereas methylated cytosines 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, the mannitol treatment caused no significative changes in methylation levels. Overall, these findings indicate that high salinity in soil causes an increment in DNA methylation on the Gl2 gene body, probably increasing its expression as usually occurs in plant genes, resulting in inhibition of root hair development.