The Assessment of Metal Resistance through the Expression of Hsp-70 and HO-1 Proteins in Giant Reed

Abstract

None of our investigations have identified stress in response to the HSP70 and HO-1 proteins in metals under stress in our study, which aimed to understand the genetic basis of the metal tolerance of Arundo donax. Thus, the present work aimed to investigate the levels of expression of two important stress-related proteins, HO-1 and HSP70, in A. donax after exposure to various metals. The plants were collected from uncontaminated sites in Abbottabad, Pakistan. Their rhizomes were grown in Hoagland solution, and upon attaining suitable biomass, the plants were used to investigate the effects of metals on protein expression. The metal treatments were carried out with synthetic wastewater containing four Cr treatments (0, 34, 66, 134, and 267 mgL−1), namely, Cd, As, Pb, Cu and Ni (0, 25, 50, 75, and 100 mgL−1), and the plants were grown for three weeks. The treatments were applied according to a randomized block design (RBD) based on hydroponics. The selected protein expression was examined after 10 days of metal exposure. For the HSP70 and HO-1 protein studies, leaves were separated following a previously reported standard procedure. The maximum level of HO-1 and HSP70 expressions was noted at 66 mgL−1 of Cr, and then it slightly declined. Significantly, high protein expression was observed at Cd exposure concentrations of 50 to 100 mgL−1. For Cu, As and Ni, significantly high HO-1 and HSP70 expressions were noted at metal exposure concentrations of 75 to 100 mgL−1. The expression levels of these two stress-related proteins showed a linear increase with increasing metal exposure in the giant reed. It is clear from the present research that HSP70 and HO-1 proteins may contribute significantly to plant tolerance to metal stress, in addition to other possible tolerance mechanisms.