| Resumo: |
An effective tissue culture is an indispensable basis for the production of transgenic plants. In this study, we investigated the induction of embryogenic callus production from the scutellum of spring wheat and subsequent regeneration of plants. Twenty-two Argentine spring wheat varieties from three breeders were screened to select promising genotypes for the optimization of the procedure. Experimental variables were the developmental stage of the immature embryos and the concentration of the growth regulator 2,4-dichlorophenoxyacetic acid (2,4-D). Two developmental stages, termed H and W, respectively (according to He et al., 1986), were selected, and their performance in culture media containing high and low concentrations of 2,4-D was examined. Parameters for the screening were: callus induction, callus proliferation on the scutellum, precocious germination of the immature embryo (as negative trait), regeneration and shoot formation and total efficiency of the in vitro culture. The best results were achieved with a combination of developmental stage H and a low concentration of 2,4-D. Scutellar callus induction and callus proliferation on the scutellum surface were positively correlated. However, scutellar callus induction, regeneration and number of shoots were independent of each other. Considerable genotype differences were found in the suitability of the varieties investigated for spring wheat propagation via in vitro culture. The cultivar Klein Brujo exhibited the highest overall culture efficiency (84.4 %) related to the number of immature embryos used and the number of plants regenerated from one embryo (9.5).
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