Induced Expression of Six ZIP Genes by Zinc Deficiency is Associated with Increased Uptake and Root to Shoot Translocation of Zn in Zn-efficient Bread Wheat Cultivars

A greenhouse experiment was conducted to investigate the expression levels of six ZRT/IRT like-protein (ZIP) genes in roots and leaves of bread wheat cultivars (Triticum aestivum L.) under soil Zn deficiency conditions. ‘Bayat’ and ‘Niknejad’ (Zn-efficient) and ‘Hirmand’ and ‘Karaj1’ (Zn-inefficient) cultivars were grown in soil Zn deficiency and control conditions with sufficient level of zinc in the medium and genes expression levels were studied in roots and leaves of the cultivars at 28 days after germination (vegetative) and 30% of heading (reproductive). The leaf, root and grain Zn concentration and content were also measured. Analysis of gene expression data revealed that in Zn starvation conditions, the expression of some ZIP genes in Zn-efficient cultivars was significantly (P ≤ 0.01) higher than those of Zn-inefficient cultivars. ZIP9 expression in root was significantly (P ≤ 0.01) higher than that of leaf, while the expression of ZIP7, ZIP10, ZIP14, and ZIP16 in root was significantly (P ≤ 0.01) lower than those of leaf. The relative expression of ZIP9, ZIP10, ZIP11, ZIP14 and ZIP16 at reproductive stage was significantly (P ≤ 0.01) higher than those in the vegetative stage. A positive and significant (P ≤ 0.01) correlation was observed between the expression of ZIP9, ZIP10 and ZIP14 in leaf at vegetative stage and both root and leaf Zn contents at the same stage under Zn deficiency conditions. The expression of ZIP7 in leaf at reproductive stage was also strongly associated with the grain Zn content under Zn deficiency conditions, hence ZIP7 could be proposed for the biofortification of bread wheat cultivars.