Optimization Of Polyploid Induction Technology And Germplasm Creation Of Cucumber

Cucumber(Cucumis sativus L.,CC,2n=2x=14)belongs to cucumber genus of cucurbitaceae and is one of the top ten vegetables in the world.The narrow genetic basis of cultivated cucumber not only limited the further improvement of yield and quality,but also weakened the adaptability of cucumber to adverse environment.Polyploidy is beneficial to plant evolution,which has significant advantages in genetic diversity and adaptability.At present,cucumber polyploid materials have been developed successively,for example,colchicine is used to induce cotyledon seedlings,germinating seeds or dry seeds to obtain European greenhouse type and North China type hairless cucumber autotetraploid,but there are few reports on the comparative study of induction effect of different induction technology systems.Therefore,in this study,the aspirating seeds,germinating seeds and cotyledon growth points were induced by colchicine with different concentrations of "JY" cucumber.The polyploid effect of different induction systems was investigated,and the agronomic characters and nutritional quality of successfully created polyploid cucumber were identified by morphological,cytological and flow cytometry identification.The main results are as follows:1.Cucumbers(2n= 2x =14)were treated with colchicine at different concentrations on aspirating seeds,germinating seeds and cotyledon growth points.The triploid(3x),tetraploid(4x)and mixed(2x +4x/ 8x+16x)plants were successfully obtained by morphological,cytological and flow cytometry identification.Among them,0.4% colchicine treated germinating seeds had the best effect of inducing tetraploid for 4 h,and the induction rate was 18%.The triploid and mixed ploid induced by 0.2% colchicine for 2 h were the best,and the induction rate was 15%.This study laid a technical foundation for the creation of cucumber polyploid germplasm.2.Cucumber polyploid plants were induced by colchicine,and T1 generation plants were obtained by self-crossing.Morphological,cytological,agronomic traits and nutritional quality of cucumber plants were compared and analyzed.Compared with diploids,polyploids showed shorter internodes,brighter leaf color,larger leaf area,larger female floral organs,four-pore pollen grains,and higher chromosome number.The contents of soluble protein,vitamin C and soluble sugar in fruit were increased,and the fruit shape index of tetraploid decreased by 27.1% compared with diploid,while the content of soluble sugar and hardness increased by 47.8% and25.8%,respectively.