Expression pattern of genes encoding bZIP56, WRKY1 and NAM-B1 transcription factors under Zn deficiency conditions in bread wheat (Triticum aestivum L.)

Bread wheat (Triticum aestivum L.) is one of the most important nutritional products in the world. Despite efforts to improve the quality of wheat, its micronutrient level is still below the optimal level for human nutrition. Zinc (Zn) deficiency in particular is a widespread problem of human nutrition in countries that rely heavily on cereal-based diets. Hence, the current investigation was performed to investigate the expression pattern of genes encoding transcription factors bZIP56, WRKY1 and NAM-B1 under Zn deficiency conditions in bread wheat.

In this investigation, two Zn-efficient (Hamoon) and –inefficient (Hirmand) bread wheat cultivars were planted under Zn deficiency (0) and adequacy (5 mg Zn / kg soil) conditions and the relative expression of the above-mentioned genes was measured in root and leaf of the cultivars in Zn deficiency conditions at two growth stages: one month after germination (vegetative stage) and 30% of heading (reproductive stage) using real time PCR technique.

The results reveled the highest expression of bZIP56 (more than 77-fold) and WRKY1 (more than 20-fold) in roots of Zn-efficient (Hamoon) cultivar at vegetative stage. Also, the expression of these genes in the leaves of Hamoon at vegetative stage was considerably increased compared to control plants. The highest expression of NAM-B1 (more than 54-fold) was observed in the leaves of Zn-inefficient (Hirmand) cultivar at reproductive stage. The expression of this gene in the roots and leaves of Zn-efficient (Hamoon) cultivar was also enhanced remarkably at both reproductive and vegetative stages, compared to control plants.

In conclusion, regarding the enhanced expression of the three studied genes at vegetative stage in the roots of Zn-efficient cultivar, they are probably involved in the activation of the transcription of the genes involved in Zn uptake in the roots under Zn deficiency conditions. Therefore, these genes could be used in the seed quality improvement and biofortification breeding programs of bread wheat for producing Zn-efficient cultivars.