POTENTIAL FUNCTIONS OF ARABIDOPSIS THALIANA HEAT SHOCK PROTEINS IN THE PLANT APOPLAST

FR ROSSI; PEREZ ROJAS S; SANCHEZ LOPEZ EDWIN; DENG B; ZHANG F; ANDRÉS GÁRRIZ; CLEMENTE MARINA; CORIGLIANO MARIANA

Salta

Congreso; Joint LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Joint LV Annual SAIB Meeting and XIV PABMB Congress

Hsp90s are found in all plant cellular compartments examined to date, including cytosol, nucleus, endoplasmic reticulum, mitochondria andchloroplasts. Besides, Hsp90s have also been found in the apoplast, even though their roles in this location remain elusive. Previously, we addedsome light to this issue by assessing the regulation of defense-associated mechanisms in Arabidopsis thaliana plants infiltrated with therecombinant Hsp90 protein rAtHsp81.2. In this trend, we showed that ROS production and callose deposition were incremented uponrAtHsp81.2 infiltration. Besides, a 24h pre-treatment of leaves with rAtHsp81.2 resulted in a reduction in the proliferation of Pseudomonassyringae pv. tomato DC3000, whereas the in vitro growth of the bacteria is not affected in the presence of rAtHsp81.2 suggesting that thisprotein may participate in the induction of defense. In the present study, we attempted to gain a deeper insight into the role played by apoplasticlocalized Hsp90s by evaluating their effects on defense gene expression. We observed that rAtHsp81.2 infiltration downregulated the expressionof PR1 and endogenous AtHsp81.2, while Pdf1.2 expression showed no statistical differences compared to mock-inoculated controls. However,pre-treatment of leaves with rAtHsp81.2 followed by infiltration with P. syringae provokes an opposite response to that in leaves infiltrated withAtHsp81.2 alone, as PR1 and AtHsp81.2 gene expression resulted up-regulated. Our results suggest that Hsp90s localized in the plant apoplastplay an active role in the activation of the plant defense mechanisms against pathogens.