The potential of synthetic hexaploid wheats to improve zinc efficiency in modern bread wheat

Synthetic hexaploid wheats (Triticum aestivum L) derived from crosses between durum wheat [Triticum turgidum ssp. durum (Desf.) Husn.] and diploid wheat (Aegilops tauschii Coss.) have been developed as a means of transferring desirable characteristics of Aegilops tauschii Coss. such as disease resistance and abiotic stress tolerance into modern bread wheat genotypes. In a growth room experiment using soil culture, we studied a group of 30 synthetic hexaploid wheat accessions together with modern wheat genotypes in order to identify new sources of zinc efficiency for further improvement of zinc efficiency in modern wheat genotypes. There was considerable genetic variation in expression of zinc deficiency symptoms (slight to severe), zinc efficiency (70-100%), shoot Zn concentration (5.8-10.5 and 33-53 mg/kg DW under deficient and sufficient Zn, respectively), shoot Zn content (3.8-10.6 and 34.0-64.6 mug/plant, under deficient and sufficient Zn, respectively) and Zn utilization (0.096-0.172 and 0.019-0.033 g DW/mug Zn under deficient and sufficient Zn, respectively) within synthetic accessions. The presence of synthetic accessions with greater zinc efficiency (100%) than zinc efficient modern wheat genotypes (85%) indicates that the synthetic hexaploids can be used to improve current levels of zinc efficiency in modern wheat genotypes. Synthetic hexaploids may also be a good source of high grain Zn concentration (28-66 mg Zn/kg seed DW).