Barley cold-induced CISP proteins contribute to the accumulation of heavy metals in roots

Abstract Cold-induced CISP genes are widely distributed in Poaceae species such as barley, rye, and wheat. In our previous study, we suggested that barley CISP proteins encoded by CISP genes, CISP1 and CISP2 , serve as an RNA chaperone and play a vital role in cold adaptation of barley. However, we found that the expression of barley CISP genes are also induced by other abiotic stresses such as heavy metal stresses. Their expression was rapidly upregulated in roots by treatment with an excess of Cu, Zn and Mn. Furthermore, we confirmed that the barley CISP proteins are mainly localized to the root apical meristems where the heavy metals are accumulated. These data suggest that the barley CISPs should play an important role in the adaptation to the heavy metal stresses. We then investigated the influence of CISP2 overexpression on Cu stress tolerance of plants. The results showed that the overexpression of CISP2 inhibits growth rate of rice and increase the accumulation of Cu in roots. Based on these findings, we proposed that the barley CISPs are multifunctional protein and involved in the accumulation of heavy metals to regulate the balance of metal ions.