| This induction research of tetraploid grapes was conducted on five cultivars of grape plantlets—'Phoenix 51','Jingxiu','Museat of Alexandria','Jingzaojing'and b, and with the inducer colchicine extracted from Vitis viniferacv. In the study, the cellular DNA weight of the reference and colchicine-treated grape plantlets was determined by the flow cytometor; the ultrastructure of the mesophyllic cells of the induced tetraploid grape plantlets and that of the original, reference diploids were compared; and the colchicine concentration of the used solution was determined by the high-performance liquid chromatographor.The main results as follow:1. The inhibiting effects of colchicine on the plantlets'growth varied with different colchicine concentrations and different lengths of time during which the grape stem fragments were treated with the colchicine solution. The inhibition effect was enhanced with an increase in both the colchicine solution concentration and the treatment period length.2. The efficiency of induction varied with different grape cultivars. The optimal treatment combination for'Phoenix 51'was to soak stem fragments in solution with a colchicine concentration of 4000 mg·L-1 for 3 d, yielding 27.5% of the original diploid plantlets induced into tetraploids. 17.5% of the'Jingxiu'diploid plantlets were induced after 3d in 4000 mg·L-1 colchicine solution. Museat of Alexandria'and b also demonstrated considerable induction rate in their optimal combinations, whereas'Jingzaojing'had not yielded any mature tetraploid plant.3. The efficiency of induction varied with different stem segments that were chosen to be treated. The nodal leaves in the upper section of stems demonstrated more rapid germination and higher mutation (i.e. induction) rate, but the tender tissues of the upper stem are more susceptible to death when soaked in solution. In contrast, the highly lignified tissues in the lower sections of stems don't readily succumb to death when soaked, but the nodal leaves there exhibit slower germination and lower mutation rate.4. The efficiency of induction varied with different lengths of the elapsed time between the removal of the terminal node and the beginning of colchicine treatment. The plantlets that were treated 2d and 3d after the terminal node removal exhibited significantly higher induction rate than those treated after 0.5d and 1d.5. Difference between the ultrastructure of mesophyllic cells of tetraploids and that of diploids existed. Both the mitochondria and mitochondrial membrane of tetraploids were damaged to a certain degree, and the inner membrane of tetraploids'chloroplasts was also somewhat thickened. |
