Evaluation of In Vitro Morphogenic Response of Triticum urartu, a Donor of Au Genome of Modern Wheat

Triticum urartu Thum. ex Gandil. is a wild diploid wheat species (2n = 2x = 14) that is an Au genome donor of modern polyploid cultivars of durum and bread wheat. In the last decade, this relict species has attracted breeders as donors of various agronomically important characteristics to broaden the genetic diversity of cultivated wheat. In addition, T. urartu can be considered as a model species for studying the evolution, biology and genomics of wheat without the cross-influence of homologous sub-genomes. Various genetic engineering technologies, including transgenesis and genome editing, may be applied to facilitate the functional characterization of genes located in A chromosomes. Such biotechnological techniques are still required for the efficient tissue culture systems to allow easy plant regeneration. The objective of our study was to assess the abilities of in vitro plant regeneration from zygotic immature embryo-derived tissues of spring and winter types of T. urartu. Three synthetic auxins, 2,4-D, Dicamba and Picloram, at four concentrations were studied to stimulate morphogenic responses in spring T. urartu. The induction medium supplemented with 4 mg·L−1 Dicamba stimulated the highest frequency of regenerable callus production (65.8%), promoting the generation of 5.7 plants. Although the presence of 2 mg·L−1 2,4-D was less effective in stimulating regenerable callus formation (53.2%) than Dicamba, it allowed the regeneration of more plants from one regenerable callus (9.3 plants). These two treatments also successfully initiated morphogenesis in winter assertions; however, their regenerative capacity was generally lower. The frequency of regenerable callus production was accession-dependent and fluctuated within 31.3 to 49.2%, with a formation of an average 2.2–5.8 plants per callus. The relatively simple and fast regeneration system described in this study could be further used as the basis for regenerating transgenic plants of T. urartu.