Isolation and characterisation of cDNA encoding a wheat heavy metal‐associated isoprenylated protein involved in stress responses

Abstract

In cells, metallochaperones are important proteins that safely transport metal ions. Heavy metal-associated isoprenylated plant proteins (HIPPs) are metallochaperones that contain a metal binding domain and a CaaX isoprenylation motif at the carboxy-terminal end. To investigate the roles of wheat heavy metal-associated isoprenylated plant protein (TaHIPP) genes in plant development and in stress responses, we isolated cDNA encoding the wheat TaHIPP1 gene, which contains a heavy metal-associated domain, nuclear localisation signals and an isoprenylation motif (CaaX motif). Quantitative real-time PCR analysis indicated that the TaHIPP1 gene was differentially expressed under biotic and abiotic stresses. Specifically, TaHIPP1 expression was up-regulated by ABA exposure or wounding. Additionally, TaHIPP1 over-expression in yeast (Schizosaccharomyces pombe) significantly increased the cell growth rate under Cu(2+) and high salinity stresses. The nuclear localisation of the protein was confirmed with confocal laser scanning microscopy of epidermal onion cells after particle bombardment with chimeric TaHIPP1-GFP constructs. In addition, TaHIPP1 was shown to enhance the susceptibility of wheat to Pst as determined by virus-induced gene silencing. These data indicate that TaHIPP1 is an important component in defence signalling pathways and may play a crucial role in the defence response of wheat to biotic and certain abiotic stresses.

Characterization of the Heavy-Metal-Associated Isoprenylated Plant Protein (HIPP) Gene Family from Triticeae Species

“…Improving wheat tolerance to Cd and reducing Cd accumulation in grains are issues that need to be addressed in current wheat breeding. Some Cd-tolerance-related genes in wheat have been reported; including HMA-containing genes [ 29 ]. This HMA domain has a highly conserved CysXXCys (X refers to any amino acid) motif comprising a beta–alpha–beta–alpha fold shape for binding heavy metals, such as Cd, Cu, or Zn [ 48 ].…”

“…The wheat heavy-metal ATPase 2 (TaHMA2) can transport Zn 2+ and Cd 2+ across membranes, and overexpression of TaHMA2 in Arabidopsis increases the root length and fresh weight and enhances Zn 2+ /Cd 2+ root-to-shoot translocation compared to that of the wild-type [ 40 , 49 ]. TaHIPP1 from common wheat contains an HMA domain, and overexpression of TaHIPP1 in yeast significantly increases the cell growth rate under Cu 2+ stress [ 29 ]. The cell number regulator 2 (TaCNR2) from common wheat is also involved in regulating heavy-metal translocation; the expression of TaCNR2 in wheat seedlings increases under Cd, Zn, and Mn treatments, and overexpression of TaCNR2 in Arabidopsis and rice plants enhances their tolerances to Cd, Zn, and Mn stresses.…”

“…The functions of HIPPs have been extensively studied in Arabidopsis [ 25 ], Oryza [ 26 ], tomato [ 27 ], barley [ 28 ], wheat [ 29 ], etc., and HIPPs have been revealed to play an important role in the maintenance of heavy-metal homeostasis and detoxification. In Arabidopsis , the expression of AtCdI19 can be induced by Cd, Hg, Fe, and Cu, and overexpression of CdI19 confers Cd tolerance in transgenic Arabidopsis [ 30 ].…”

Genome-wide association study (GWAS) reveals genetic loci of lead (Pb) tolerance during seedling establishment in rapeseed (Brassica napus L.)

“…It is well known that HIPPs, containing HM-binding domain (HMA, pfam00403.6), have important functions in plant responses to both biotic and abiotic stresses [72,73]. In Arabidopsis, the AtHIPP20, AtHIPP22, AtHIPP26 and AtHIPP27 genes were involved in Cd detoxification [74,75].…”

Genome-wide association study (GWAS) reveals genetic loci of lead (Pb) tolerance during seedling establishment in rapeseed (Brassica napus L.)

“…It is well known that HIPPs, containing HM-binding domain (HMA, pfam00403.6), have important functions in plant responses to both biotic and abiotic stresses [73,74]. In Arabidopsis, the AtHIPP20, AtHIPP22, AtHIPP26 and AtHIPP27 genes were involved in Cd detoxification [75,76].…”