Expression of high zinc efficiency of Aegilops tauschii and Triticum monococcum in synthetic hexaploid wheats

The effect of varied zinc (Zn) supply on shoot and root dry matter producti on, severity of Zn deficiency symptoms and Zn tissue concentrations was stu died in two Triticum turgidum (BBAA) genotypes and three synthetic hexaploi d wheat genotypes by growing plants in a Zn-deficient calcareous soil under greenhouse conditions with (+Zn=5 mg kg(-1) soil) and without (-Zn) Zn sup ply. Two synthetic wheats (BBAADD) were derived from two different Aegilops tauschii (DD) accessions using same Triticum turgidum (BBAA), while one sy nthetic wheat (BBAAAA) was derived from Triticum turgidum (BBAA) and Tritic um monococcum (AA). Visible symptoms of Zn deficiency, such as occurrence o f necrotic patches on leaves and reduction in shoot elongation developed mo re rapidly and severely in tetraploid wheats than in synthetic hexaploid wh eats. Correspondingly, decreases in shoot and root dry matter production du e to Zn deficiency were higher in tetraploid wheats than in synthetic hexap loid wheats. Transfer of the DD genome from Aegilops tauschii or the AA gen ome from Triticum monococcum to tetraploid wheat greatly improved root and particularly shoot growth under Zn-deficient, but not under Zn-sufficient c onditions. Better growth and lesser Zn deficiency symptoms in synthetic hex aploid wheats than in tetraploid wheats were not accompanied by increases i n Zn concentration per unit dry weight, but related more to the total amoun t of Zn per shoot, especially in the case of synthetic wheats derived from Aegilops tauschii. This result indicates higher Zn uptake capacity of synth etic wheats. The results demonstrated that the genes for high Zn efficiency from Aegilops tauschii (DD) and Triticum monococcum (AA) are expressed in the synthetic hexaploid wheats. These wheat relatives can be used as valuab le sources of genes for improvement of Zn efficiency in wheat.