Abstract :
Response of five cultivars of Iranian bread wheat to mature embryo culture and different concentrations of ABA was examined. Mature embryos from five cultivars (Tabasi, Bolani, Shiraz, Shoaleh and Azar) were placed in MS medium supplemented with 10 mg/l 2-4-D and 30 g/l sucrose and under different levels of ABA (0, 2, 4, 6 and 8 mg /l). Callus growth was measured by volume using a hoker scale. There were significant differences among cultivars in callus growth rates. Tabasi and Bolani showed the best and the least callus growth, respectively. In addition, ABA levels had significant effects in callus induction. The best and the least callus volume were observed in control and 8 mg/l ABA treatment, respectively. In fact, the more hormone used, the less callus gained. The interaction between ABA levels and cultivars was not significant, indicating this hormone in all levels affected callus induction of all cultivars in the same manner. In control treatment calluses had the brightest color and with increase in ABA concentration calluses became darker; in 8 mg/l ABA calluses became dark-brown. In this manner, with increase in ABA concentration in mediums calluses compacted and the most friable calluses were observed in control medium. When regeneration rates were compared, there were significant differences among cultivars and ABA levels. The best and the least regeneration percentage were observed in control and 8 mg/l ABA level, respectively. Tabasi showed the maximum regeneration rate. In contrast with callus induction, the interaction between cultivars and ABA levels was significant and suggested that different ABA levels had different effects on cultivars.
