| Rosa chinensis originated from China,is one of ten traditional flowers of China and the four major cut flowers of the world.It is popularized worldwide because of its fragrance,abundant colors and continuous flowering.In this research,Rosa chinensis ’Old blush’ was used to induce tetraploid plants by colchicine treatment,and the resulted plants were identified and analyzed.The main findings are stated below:1.The stem tips were soaked in solution with different concentrations of colchicine for different time to induce tetraploid.By chromosome counting,the number of chromosomes in untreated plant was 14 and that of tetraploid plant was 28.The results showed that 4 g/L colchicine solution with 48 h treatment was the best combination for tetraploid induction,and the corresponding induction rate was 16.67%,the lethal rate was 46.67%.2.The leaf and stomata of tetraploid were significantly different from diploid after transplanted into soil for 60 d.The length of the guard cell of diploid leaf was 26.9 μm and that of tetraploid plant was 37.6 μm.The number of chloroplast per stoma of the diploid was 13.5 and that of tetraploid plant was 24.2.On the contrary,the number of stomata in diploid under a 10 × 40 field of microscope was 15.4 and that of tetraploid plant was 10.9.At the same time,the leaf width of the tetraploid was changed obviously.The leaf width in diploid plant was 2.071 cm and that of tetraploid plant was 2.896 cm.Compared with the leaf width,the leaf length increased slightly.The leaf length of the tetraploid plant was 4.915 cm and that of the diploid plant was 4.294 cm.The leaf shape index(length/width)of tetraploid plant was 1.697 and that of diploid plant was 2.109.The leaf shape of tetraploid was ellipse and that of diploid became narrower.The ten-leaf thickness of tetraploid plant was 0.392 cm and that of diploid plant was 0.304 cm.It was found by DUS test the chromosome doubling has effect on the leaf and sepal development.3.The activities of superoxide dismutase and peroxidase in tetraploid leaf were significantly higher than diploid plants.The SOD of the tetraploid plant was 200.2 U/g FW and that of diploid plant was 156.6 U/g FW;the POD of the tetraploid plant was 140.3 U/g FW and that of the diploid plant was 81.4 U/g FW,this suggested the better stress-resistance of tetraploid plant than diploid plant.The result of SSR analysis showed that the band features from PCR between diploid and tetraploid plant were identical by using 17 primers.We can conclude that the morphological and physiological changes of tetraploid are all caused by chromosome doubling.The tetraploid plant was identified as the homologous polyploid plant of the Rosa chinensis ’Old blush’.4.The experimental results showed that the optimum medium for tetraploid propagation was MS+0.6 mg/L 6-BA+0.07 mg/L NAA+30 g/L Glu+6.5 g/L Agar,and the multiplication of adventitious buds of this treatment was the highest,and the multiplication coefficient is 3.30. |
