Variation in zinc efficiency among and within Aegilops species

Fifteen accessions of Aegilops tauschii (DD), 10 of Ae. speltoides (SS) and 8 of the tetraploid Aegilops species sharing the U genome were used to stu dy the influence of varied zinc (Zn) supply on development of Zn-deficiency symptoms, and on shoot dry weight and Zn concentration. Plants were grown in a Zn-deficient calcareous soil under greenhouse conditions with (+Zn = 5 mg kg(-1) soil) and without (-Zn) Zn supply. Four accessions of wild tetra ploid wheat, Triticum turgidum var. dicoccoides (BBAA), a group known for i ts high sensitivity to Zn-deficiency, were used in the experiments for comp arison. As expected, the accessions of wild T. turgidum var. dicoccoides sh owed the highest sensitivity to Zn deficiency, and had more severe leaf sym ptoms of Zn deficiency (whitish-brown necrotic patches). Among the Aegilops species, leaf symptoms of Zn deficiency were, in general, more distinct in Ae. tauschii (DD) and least in Ae. speltoides (SS). Zinc efficiency, expre ssed as the percentage of shoot dry weight produced under conditions of Zn deficiency compared to Zn supply, averaged, 15% for T. turgidum, 32% for Ae . tauschii, 52% for Ae. speltoides and 61% for the tetraploid Aegilops spec ies carrying the U genome. Differences in Zn efficiency among and within Ae gilops species and T. turgidum were significantly correlated with the Zn am ount per shoot, but not with the Zn amount per unit dry weight of shoots. T he results show that Aegilops species can be exploited as an important gene tic source for Zn efficiency genes, particularly Ae. speltoides var. ligust ica (SS) and Ae. triuncialis (UUCC). Transfer of these genes to cultivated modem wheat may bring about a greater variation in Zn efficiency in wheat, and facilitate production of Zn-efficient modern wheat cultivars for Zn-def icient soil conditions.