| Zoysia matrella, namely manila grass, is an excellent warm-season turf-grass species grown in many countries of the tropical and subtropical areas. It’s fine-texture, green quality, formation of dense lawn, and good tolerance to drought, heat and wearing, which make it very popular to lawn establishment applied extensively in South of the Yangtze river basin and region. However, its slow speed of lawn establishment, and its susceptibility to cold and to certain plant pathogens, would be unfavorable for the wider application of manila grass. The fecundity is very low and only vegetative propagated by stolons in nature, so conventional hybridization breeding can’t be applied for its genetic improvement. Thus modern biological technologies such as somaclonal variation and genetic transformation are an effective and important way to improve its qualities of lawn establishment and resistance to stress. In this paper, the effects of different concentration cytokinins and their combinations on the subculture proliferation and regeneration of embryonic callus were researched in order to select the optimal concentration cytokinins and combination, which could provide efficient and stable receptor system for modern breeding technology in manila grass. The primary results were summarized as follows:1. When the medium contains0.10mg/1of KT or0.15mg/1of TDZ or0.15mg/1ZT or0.1mg/l BA, proliferation rate of embryonic callus are highest and significantly higher than control (200.1%) after4weeks,315.0%,283.9%,281.1%and275.0%, respectively. The highest proliferation rate of embryonic callus in treatments of different combinations of cytokinins was0.10mg/1BA,0.20mg/1KT,0.15mg/1ZT and0.10mg/1TDZ, reaching331.3%after4weeks. And the callus maintained for10years remains embryonic very well. Therefore, the treatment described above could be used for propagation of receptor materials in genetic transformation and somaclonal variation selection.2. During the regeneration of different cytokinin treatments, the highest regeneration rate and shooting differentiation rate were the regeneration medium containing ZT0.15mg/1. And the highest regeneration rate was60.3%and the total number of shooting differentiation was142.0, which were2.41times and2.41times than those of control. Followed by regeneration medium containing TDZ0.10mg/1, the regeneration rate was56.3%and the total number of shoot differentiation was110.3. Considering the rooting growth, it was found that the treatments of ZT0.15mg/l, KT0.05and0.10mg/l or ZR0.10mg/l significantly made the roots growing better than the control and other treatments, whereas TDZ significantly inhibited the growth of roots, the shoots developed on the mediums containing TDZ probably needed to be transferred to rooting mediums for rooting. The results of regeneration treated by different combinations of cytokinins and2,4-D indicated that addition of2,4-D could inhibit the regeneration of embryonic callus and the superposition of different cytokinins made the total concentration excessive, which decreased the rate of regeneration. Therefore, it was proposed that0.15mg/1of ZT could be better to promote regeneration of embryonic callus in manila grass.3. The activities of antioxidant enzymes and the contents of soluble proteins changed significantly during regeneration of embryonic callus. The results showed that high levels of SOD activities and low levels of CAT and POD activities were associated with differentiation of embryonic callus and development of somatic embryos, and the combination of them regulated the differentiation and development of embryonic callus and maturity of somatic embryos. The changes of the soluble proteins contents in the regeneration process could be the result of gene expression and regulation. Appropriate concentration of cytokinins could regulate the activities of antioxidant enzymes, promoting the differentiation of embryonic callus. Or the inappropriate cytokinins resulted in oxidative stress, which could affect the percentage of regeneration of embryonic callus in manila grass. |
PDF Full Text Request