Study of Dedifferentiation Characteristics from Immature Wheat Embryos in Sichuan

Immature embryos from 45 common wheat genotypes included the improved cultivars, lines and local varieties in Sichuan were cultured on both Medium Ⅰ(N 6 with 2,4 D) and Medium Ⅱ(N 6 with 2,4 D and KT) , and the dedifferentiation characteristics was investigated. The results showed: (1) Time of callus formation among the cultivars was obviously different. The mean time emerged callus at 50% ranged from 2.0 to 11.0 days. Dalizao that induced callus at 100% was only after inoculated 4.5 days, while other cultivars had not achieved after cultured for 30 days. 44.4% of the 45 cultivars relatively evenly formed callus. (2) The callus induction frequencies ranged from 65.63 % to 100.00% among the materials, and 93.3% of them induced callus at more than 90%. In addition, there was more great difference among the lines than among the cultivars. (3) The embryogenetic callus formation rates ranged from 0.00% to 47.62% among the tested materials. Majority of materials had relative parallel in the tendency of higher or lower frequency though the actual frequency fluctuated between the two media. The fact implied that the trait might be stably expressed. (4) The growth rate of callus was different among the cultivars. 17.8% of them produced the callus at 50 mg/embryo. The fresh callus weight of Dalizao was at 245.50 mg/embryo, but that of Fan 6 just at 9.35 mg/embryo. The effects of the media varied with the cultivars. That is, some materials yielded almost equal fresh callus weight on the two media, so their callus growth rate was relatively stable. However, others produced more great fresh callus weight on Medium Ⅱ than on Medium Ⅰ. (5) The direct germination of cultured immature embryos was observed. The germination frequency was varied with the cultivars and the media. Of the cultivars, the highest was Dalizao, at 75.81%, and the lowest was just at 0.00%. However, the direct germination might be efficiently restrained by using the medium without KT.