Plant regeneration from immature embryos of 48 elite CIMMYT bread wheats

Forty-eight bread wheat (Triticum aestivum L.) released cultivars and elite advanced lines were evaluated for their ability to produce embryogenic callus using three different media. Basal N6 medium supplemented with dicamba (E1), MS medium containing 2,4-D (E3) or MS medium containing 2,4-D plus different amino acids (E5) were used for callus initiation and maintenance. Plant regeneration was achieved on basal MS medium with indole-3-acetic acid (IAA) and 6-benzylamino purine (BAP) and rooting on MS with 1-naphthaleneacetic acid (NAA). Percentage regeneration varied widely with both genotype and initiation medium, with values ranging from 2% to 94%. The number of plantlets produced per embryo ranged from 6 to 42. Thirteen genotypes showed at least 50% regeneration after culture on E5 medium; 3 genotypes after culture on E3 initiation medium and 1 after initiation on E1. After four subcultures, over a 16-week period, 41 genotypes (85%) lost their ability to regenerate plants while the remaining 7 lines (15%) retained plant regeneration potential but at reduced levels. E3 medium was found to be the best for maintaining regeneration potential after four subcultures.