Improvement of in vitro culture response of elite wheat cultivars by selecting the source spike, the scutellum size and the temperature for the induction of embryogenesis

High frequencies of regeneration are desirable characteristics of in vitro culture from elite wheat cultivars. The effect of the source spike, the scutellum size and the induction temperature on embryogenesis, regeneration and number of plants per explant were optimized in three varieties of wheat and later determined in fifteen varieties of both bread and durum wheat. The highest frequencies of embryogenesis, regeneration and plants per explant were obtained when the first spike was used as source of scutella and decreased using the scutella from the second and third spikes. Scutella from the third spike yielded half the number of plants per explant than those from the first spike. Significant differences were also found for embryogenesis, regeneration and plants per explant as affected by scutellum size. The number of plants per explant drastically decreased in commercial varieties when scutella larger than 2.0 mm were used. The optimum induction temperature was 21 and 25°C for commercial and model genotypes, respectively. However, no differences were found for the number of plants per explant as affected by the induction temperature. The in vitro culture response of twelve and four cultivars of, respectively, bread and durum wheat were then determined. In all wheat varieties tested embryogenesis, regeneration and plants per explant varied over a wide range of values. In elite wheat varieties the selection of the source spike and the scutellum size can yield high frequencies of embryogenesis and regeneration and high numbers of plants per explant.