SMALL HEAT SHOCK PROTEIN GENES HARBORING PUTATIVE BIDIRECTIONAL PROMOTERS IN ARABIDOPSIS THALIANA

FERRARO G; FEUSSNER I; ESCOBAR MR; VALLE EM

Corrientes

Congreso; XXI Reunión Argentina de Fisiología Vegetal; 2016

SAFV

Bidirectional promoters (BDP) are defined as intergenic regions that can drive the expression of two adjacent genes located head to head in opposite strands of DNA. These BDP are important for transgene stacking. In this study we characterized three pairs of small Heat Shock Protein (sHSP) genes harbouring putative BDP: two from chloroplast (PTC52 and SKL2) and one from mitochondria (HSP23.5). sHSPs belong to a super family of chaperones and are rapidly induced under different stress conditions. The putative BDPs were cloned in frame with a reporter gene (GUS) and used to transform Arabidopsis. Heat, cold, salt, oxidative and osmotic stresses were assayed in transgenic seedlings. Through bioinformatic tools we found that the three intergenic regions contain a number of stress responsive cis-regulatory elements. GUS expression in both orientations showed differential regulation under normal and the stress conditions. Furthermore, transcript analysis showed the same stress inducible expression profiles. Particularly interesting was HSP23.5 and its pair, encoding a Golgi complex component. HSP23.5 was highly induced under heat stress but the expression of its neighbor gene was higher in all the other conditions. These results provide new insights into the complex regulation of bidirectional promoters and divergent gene pairs.