Regeneration potential of CIMMYT durum wheat and triticale varieties from immature embryos

Twenty-five durum wheat elite advanced lines and released varieties, and fi ve triticale varieties were evaluated for their ability to produce embryoge nic callus using three different media. For callus initiation and maintenan ce there were basal Murashige and Skoog (MS) medium containing double strai ns of macroelements and 2.5 mg/l 2,4D (DW1) basal MS medium containing 2.0 mg/l 2,4D (DW2), or basal MS medium supplemented with 1.0 mg/l 2,4 D and co conut milk (DW3). Plant regeneration was achieved on basal MS medium with i ndoleacetic acid and 6-benzylaminopurine, and plants rooted on MS with 1-na phthaleneacetic acid. DW3 medium proved better than the other media tested for embryogenic callus initiation and maintenance. Regeneration rates varie d widely with both genotype and initiation medium, with values ranging from no regeneration to 100% regeneration; the plantlets produced per embryo ra nged from five to 20. Fourteen of the durum wheat genotypes showed 63-100% regeneration from DW3 callus formation medium, four lines from DW I medium, and two lines from DW2. Four of the triticale varieties had regeneration o f 48-100% from DW3 medium. After six subcultures, over a 6-month period, ge notypes lost their ability to regenerate plants. Only 10 lines retained som e plant regeneration potential but regeneration was at reduced levels. Succ essful regeneration of durum wheat and triticale varieties will be used as an integral part of the transformation process.