Studies On Establishment Of Regeneration Systemand Polyploid Induction Of Lagerstroemia Indica

One of the important flower trait for crapemyrtle is the duration of summer bloom and related ability of a cultivar to rebloom. It still presents some problems in landscape application, such as lack of varieties with larger and denser flowers. Plant with polyploid had the traits of enhanced resistance and larger colorful flowers. Polyploid breeding has been applied in new varieties cultivating of ornamental plants widely. However, it was in the initial stage of L. indica breeding. In this paper, the methods of propagation and regeneration of L. indica were studied, and colchicine was used to treat nodes in vitro for thepolypoid inducement. Morphological and anatomical characteristics of leaf, chromosome count and flow cytometry were used to identify the polyploidy of plants . The results were listed as follows:1 .The propagation systems of L. indica were established. The optimal medium for L. indica was MS+BA1.0 mg·L^-1+NAA 0.1 mg·L^-1, in which 50 percent plants growed. MS+BA1.0 mg·L^-1+NAA 0.1 mg·L^-1 was more effective medium for the multiplication of nodes than other combinations of plant growth regulators. The best medium for rooting was 1/2MS+NAA0.5 mg·L^-1.2. The leaf regeneration syetems of L. indica were established. The optimal inductive medium for L. indica was MS+2,4-D1 mg·L^-1+BA1 mg·L^-1. 2,4-D was the most important and essential factor in medium.3. Nodes excised from in vitro shoots were treated with different concentrations of colchicine under 3 different conditions. Tetraploid plants were obtained after nodes were cultured in liquid medium containing 300 ppm colchicine for 10 d.4. The detection of L. indica's ploidy. Morphological and anatomical characteristics of leaf, including leaf index, stomata size and frequency, stomata index (length/width), and chloroplast in stomata guard cells were shown to be correlated with the ploidy of crape myrtle plant. The number of chloroplast in stomata guard cells found to be a stable marker in discriminating plants with different ploidy levels, and chromosome count or flow cytometry could be utilized to precisely confirm the results.