HO-1 gene expresion is not epigenetically restricted and involves stress-related transcription factor

SANTA-CRUZ D.; YANNARELLI G.; PACIENZA N.; ZILLI C.; TOMARO ML.; BALESTRASSE K.

Buenos Aires

Congreso; Molecular mechanisms in cell signaling and gene expression; 2013

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Hemo oxygenase-1 (HO-1) plays a protective role against oxidative stress in plants. The mechanisms regulating its expression, however, remain unclear. Here we studied the methylation state of a GC rich HO-1 promoter region and the expression of several environmental stress associated-transcription factors (TFs) in soybean plants subjected to ultraviolet-B (UV-B) radiation. Genomic DNA and total RNA were isolated from leaves of plants irradiated with 7.5 and 15 kJ.m-2 UV-B. A 304 bp HO-1 promoter region was amplified by PCR from sodium bisulfite-treated DNA, cloned into pGEM-T plasmid vector and evaluated by DNA sequencing. Bisulfite sequencing analysis showed similar HO-1 promoter methylation levels in control and UV-B-treated plants (C: 3.0±0.6%; 7.5: 3.14±0.5%; 15: 2.9±0.5%). Interestingly, HO-1 promoter was strongly unmethylated in control plants. Quantitative RT-PCR of TFs showed that GmMYB177, GmMYBJ6 and GmWRKY21 but not GmWRK13 were induced by UV-B irradiation, inferring that the former group mediates HO-1 up-regulation. These results indicate that HO-1 gene expression is not epigenetically regulated. Moreover, the low level of HO-1 promoter methylation suggests that this antioxidant enzyme can rapidly respond to environmental stress. Finally, this study has identified some stress-related TFs involved in HO-1 up-regulation under UV-B radiation.