Screening of different wild and modern wheats for zinc efficiency and evaluation of plant traits affecting expression of tolerance to zinc deficiency

In this PhD study different wild and primitive wheats, wild relatives of wheat and addition, substitution and translocation lines of wheat were used to study i) genotypic variation in tolerance to Zn deficiency, ii) role of wheat genomes (i.e., A, BBAA, DD, BBAADD) and rye genome (i.e., RR) in expression of high Zn efficiency, in) chromosomal localization of genes affecting Zn efficiency, and iv) physiological mechanisms affecting expression of Zn efficiency, i.e., release of Zn- mobilizing compounds from roots (phytosiderophores) and uptake and root-to-shoot translocation of Zn. The results showed that rye has an exceptionally high Zn efficiency and the genes involved in high Zn efficiency in rye can be partly transferred to wheat, and might be located on the İR, 2R and 7R chromosomes of rye, particularly on their short arms. Aegilops species and diploid (A), tetraploid (BBAA), hexaploid (BBAADD) primitive and wild wheats were tested for tolerance to Zn deficiency in a Zn-deficient soil under greenhouse conditions. Among the Aegilops species, Ae. speltoides with S genome and the Aegilops species sharing U genome were much more resistant to Zn deficiency \haaAe. tauschii (DD). Ae. speltoides (SS) and Ae. triuncialis (UUCC) were selected to be major gene resources for improving modern cultivated durum and bread wheats for high Zn efficiency. Among wild and primitive wheats tetraploid wheats (BBAA) were very sensitive to Zn deficiency while diploid (AA) and hexaploid wheats (BBAADD) were resistant The results suggested that the genes affecting expression of high Zn efficiency are possibly located on the A and D genomes. It seems likely that the genome B posseses supressor genes for Zn efficiency. In the genotypes representing diploid, tetraploid and hexaploid wheats and Ae. tauschii, capacities for phytosiderophore (PS) release from roots and Zn uptake and root-to-shoot translocation were studied under controlled environmental conditions. Results obtained showed that under Zn-deficient conditions the highest amount of phytosiderophore release was found in hexaploid wheats (BBAADD), while Zn deficiency-sensitive tetraploid (BBAA) wheats released the lowest amount of phytosiderophore. 6SZinc uptake and root-to-shoot translocation capacities are affected by wheat genomes diffentially depending on Zn efficiencies of genotpypes. Key words: Aegilops, wild and primitive wheats, zinc absorbtion, zinc deficiency, zinc efficiency n