Study On Rapid Propagation And Polyploid Induction Of Platostoma Palustre

Platostoma palustre（Blume）A.J.Paton is an important medicinal and edible plant in China,with values in heat-clearing,detoxifying,lung-moistening,cough-relieving,anti-inflammatory,and pain-relieving.Its unique taste and refreshing flavor make it an important ingredient in cold drinks,desserts,jellies,and herbal teas.However,the traditional propagation method of P.palustreis is by cuttings,which can easily lead to viral infections and cause large-scale yield reduction.In addition,the diploid plants of P.palustreis are shorter and have lower yields,which need further improvement.Therefore,this study utilizes P.palustre as the research material,firstly establishes an in vitro rapid propagation system,and then,based on this system,utilizes colchicine as a polyploid inducer to cultivate new polyploid germplasms of P.palustreis.The main research results are as follows:（1）In the callus induction test of P.palustreis,stem segments were found to be the best inducing materials and the most suitable medium was MS medium supplemented with 25 g/L sucrose,7 g/L agar,0.50 mg/L 2,4-D,and 0.20 mg/L NAA,with a callus induction rate of99.60%.The addition of 0.05 mg/L PVP had a certain effect in inhibiting browning of callus tissue.（2）In the callus differentiation test of P.palustreis,the most suitable medium was MS medium supplemented with 25 g/L sucrose,7 g/L agar,0.50 mg/L kinetin,0.30 mg/L NAA,and 1 mg/L 6-BA,with a differentiation rate of 66%.（3）In the bud proliferation test of P.palustreis,the terminal bud was the best inoculation material,and the most suitable medium was MS medium supplemented with 25 g/L sucrose,7g/L agar,0.30 mg/L kinetin,0.05 mg/L NAA,and 0.10 mg/L 6-BA,with a multiplication rate of 7.50 times.（4）In the experiment of microstem tip culture of P.palustreis,the most suitable medium was MS medium supplemented with 25 g/L sucrose,7 g/L agar,0.05 mg/L IBA,and 0.15mg/L 6-BA,with a multiplication rate of 4.08 times.（5）In the rooting induction of P.palustreis,the top buds were the most suitable inoculation material,and the most suitable medium was 1/2 MS medium supplemented with25 g/L sucrose,7 g/L agar,1.50 g/L activated charcoal,and 0.30 mg/L NAA,with an average of 11.28 roots induced per plant and an average root length of 1.21 cm.（6）In the transplanting experiment of P.palustreis,the best transplantation substrate was a mixture of Yellow clay and peat（1:2）,with a survival rate of 95.50%.（7）In the induction study of colchicine on the polyploid of P.palustreis,the best induction effect was achieved by using the stem tip tissue culture method.The optimal treatment was soaking in a colchicine solution of 150 mg/L for 4 days,dissecting the micro stem tips with a length of 0.5-1 mm under a dissecting microscope,and transferring them to a differentiation medium,with an induction rate of 26.67%,death rate of 10%,and a total of 114X plants obtained.（8）In chromosome counting and ploidy identification were performed by observing the chromosomes under a microscope using stem tips of P.palustreis.It was found that the chromosome number of diploid P.palustreis was 2n=2x=32,the chromosome number of tetraploid P.palustreis was 2n=4x=64,and there were some chimeric individuals with chromosome numbers between 32 and 64.（9）In the comparison of characteristics between tetraploid and diploid P.palustreis,it was found that the leaves of tetraploid plants were darker,thicker,and had a higher number of leaves.The stem of tetraploid plants was thicker and the root system was more developed.Leaf length,width,area,number of chloroplasts,length and width of guard cells,chlorophyll content,nitrogen content,transpiration rate,photosynthetic rate,stomatal conductance,etc.of tetraploid plants were all higher than those of diploid plants.The stomatal density and intercellular CO₂of diploid plants were higher than those of tetraploid plants.The differences in the above-mentioned indicators were extremely significant.This study has successfully developed tissue culture and rapid propagation techniques for P.palustreis,and cultivated tetraploid P.palustreis,significantly improving the efficiency and yield of propagation,and providing disease-free and high-quality seedlings for production.This has positive implications for the development of the P.palustreis industry.