| Heracleum dissectum Ledeb is a herbaceous herb of the Umbelliferae,and it belongs to Heracleum L,the scientific name is Heracleum dissectum.Heracleum dissectum Ledeb is a shade-tolerant plant,which is mostly distributed in Northeast and North forest district of China,its also distributed in Russia and North Korea.Heracleum dissectum Ledeb has high nutritional value and is rich in vitamin A,vitamin C,sugar,protein and other substances.It has both edible and medicinal value.The stems and tender leaves of Heracleum dissectum Ledeb taste delicious and there are a variety of cooking methods of them.Heracleum dissectum Ledeb is a kind of green and healthy health vegetables.Its root can be used as medicine,it can treat rheumatism,high blood pressure,waist and knee pain etal.As people pay more and more attention to wild vegetables,wild plants such as Heracleum dissectum Ledeb become well known.Due to the increasing demand for wild vegetables and the shortage of wild resources,artificial cultivation of Heracleum dissectum Ledeb seeds is very necessary.The embryo development of Heracleum dissectum Ledeb is not fully developed,the seed germination rate is low after sowing and the nursery cycle is long,which has become the limiting factor for large-scale artificial cultivation of Heracleum dissectum Ledeb.According to the dormancy characteristics of Heracleum dissectum Ledeb seeds,this study used Heracleum dissectum Ledeb seeds as test materials,on the basis of variable temperature stratification combined with exogenous GA treatment,regular sampling was used to observed the morphological changes of seed embryos during after-ripening process.The morphological index and physiological,biochemical index of seed embryo were measured.In order to find the best treatment method to relieve the dormancy of Heracleum dissectum Ledeb seeds.To provide theoretical basis and technical support for the industrialization development of Heracleum dissectum Ledeb seeds.GA20ox is the key enzyme in the pathway of GA synthesis.Bioinformatics analysis of GA20ox and analysis of the relative expression level of GA20ox under different concentrations of GA,which laid a theoretical foundation for exploring the molecular mechanism of dormancy of Heracleum dissectum Ledeb seeds.The results shows:（1）The embryos haven’t completed the after-ripening process after the Heracleum dissectum Ledeb seeds are harvested.Most of them during the heart-shaped embryo period.Soaking seeds with GA before stratification can make the embryos complete the morphology and post-mature in advance.Compared with the control,400 mg·L-1 GA can make the embryos complete the morphology after-ripening process about 30 days in advance.（2）With the change of material metabolism in the process of seed dormancy release,starch and crude fat showed a downward trend in the process of dormancy release,soluble sugar increased at first and then decreased,and soluble protein stratification fluctuated greatly in the process of soluble protein stratification.It shows the trend of rising first,then falling,then rising and then falling.（3）GA20ox bioinformatics analysis:The full length of GA20ox gene is 1131 bp,encoding a total of 364 amino acids;the protein is mainly located in the cytoplasm and its expression product is a stable hydrophilic protein;the secondary structure prediction shows that it is a mixed protein;the homologous alignment results show that the amino acid sequence of GA20ox has low homology in different species;the phylogenetic tree results show that GA20ox is closely related to Panax ginseng and distant to Paeonia suffruticosa and Populus tomentosa.（4）The relative expression level of GA20ox gene was analyzed by qRT-PCR.The results showed that the expression of GA20ox decreased gradually with the extension of stratification time,and the expression level of GA20ox was the highest at 15 days after 200 mg·L-1GA treatment,while high concentration of GA inhibited the expression level of GA20ox. |
