CALLUS INDUCTION AND PLANT-REGENERATION FROM IMMATURE AND MATURE EMBRYOS OF WINTER DURUM-WHEAT GENOTYPES

Seven genotypes of winter durum wheat (Triticum durum Desf.) were cult ured to establish an efficient method of callus formation and plant re generation from mature embryo culture, and to compare the responses of immature and mature embryo cultures. Immature embryos were asepticall y dissected from seeds and placed, with the scutellum upwards, in dish es containing Murashige and Skoog's (MS) mineral salts and 2 mg 2,4-di chlorophenoxyacetic acid (2,4-D) per litre. Calli and regenerated plan ts were maintained on 2,4-D-free medium. Mature embryos were moved sli ghtly on the imbibed seeds. For callus formation, the seeds with moved embryos were placed, furrow downwards, in dishes containing 8 mg 2,4- D per litre. The developed calli and regenerated plants were maintaine d on the MS medium. Plants regenerated from both embryo cultures were vernalized and grown to maturity in soil. Variability was observed amo ng the wheat genotypes tested for various culture responses in both ex plant cultures. Callus induction rate and regeneration capacity of cal lus were independent of each other. Mature embryos have a low frequenc y of callus induction but a high regeneration capacity. Considering av ailability, rapidity and reliability, this form of mature embryo cultu re can be used as an alternative method for immature embryo culture.