Characterization of a Type 1 Metallothionein Gene from the Stresses-Tolerant Plant Ziziphus jujuba

Abstract

Plant metallothioneins (MTs) are a family of low molecular weight, cysteine-rich, and metal-binding proteins, which play an important role in the detoxification of heavy metal ions, osmotic stresses, and hormone treatment. Sequence analysis revealed that the open-reading frame (ORF) of ZjMT was 225 bp, which encodes a protein composed of 75 amino acid residues with a calculated molecular mass of 7.376 kDa and a predicated isoelectric point (pI) of 4.83. ZjMT belongs to the type I MT, which consists of two highly conserved cysteine-rich terminal domains linked by a cysteine free region. Our studies showed that ZjMT was primarily localized in the cytoplasm and the nucleus of cells and ZjMT expression was up-regulated by NaCl, CdCl2 and polyethylene glycol (PEG) treatments. Constitutive expression of ZjMT in wild type Arabidopsis plants enhanced their tolerance to NaCl stress during the germination stage. Compared with the wild type, transgenic plants accumulate more Cd2+ in root, but less in leaf, suggesting that ZjMT may have a function in Cd2+ retension in roots and, therefore, decrease the toxicity of Cd2+.

Identification of Reference Genes for qRT‐PCR Gene Expression Studies during Seed Development and under Abiotic Stresses in Cyamopsis tetragonoloba

“…The results obtained with the most stable reference gene were found to be in agreement with the results of the expression of CtMT1 in the tissues of other plants; however, the results obtained using the least stable reference genes were contradictory to the findings of previous works (Hudspeth et al, 1996;Yang et al, 2009;Ahn et al, 2012;Yang et al, 2015). The results obtained with the most stable reference gene were found to be in agreement with the results of the expression of CtMT1 in the tissues of other plants; however, the results obtained using the least stable reference genes were contradictory to the findings of previous works (Hudspeth et al, 1996;Yang et al, 2009;Ahn et al, 2012;Yang et al, 2015).…”

Expression analysis of metallothioneins and mineral contents in tomato (Lycopersicon esculentum) under heavy metal stress

“…In this study, Cu reached the aerial parts of the tomato, and the copper concentration order was roots, leaves and fruits. Copper is an essential element, but it may be toxic to both humans and animals when its concentration exceeds safe limits …”

“…The expression characteristics of MTs differ according to species and tissues . MT1 is predominantly expressed in roots and leaves, MT2 is expressed primarily in leaves and stems, MT3 is expressed in ripening fruits, and MT4 is usually expressed in developing seeds …”

“…Although some studies of various plants such as Lycopersicon esculentum , Populus trichocarpa x deltoides , Arachis hypogaea Populus alba , Gossypium hirsutum , Glycine max , Kandelia candel , Elaeis guineensis and Ziziphus jujupa have worked on gene expression, there is no general conclusion about the expression of MTs. Most research focused only on one MT type or plant tissue.…”

“…18 MT1 is predominantly expressed in roots and leaves, MT2 is expressed primarily in leaves and stems, MT3 is expressed in ripening fruits, and MT4 is usually expressed in developing seeds. 19,20 Plants take up heavy metals and accumulate them in different organs. Heavy metal and nutrient contents of plants depend on growth mediums.…”