| Heracleum moellendorffii Hance is one of the main wild vegetable species in northeast China,Its young stems and leaves are delicious vegetables,the whole plant is not only a good feed,but also can be used as medicine.This kind of medicine and food homologous wild vegetable is very popular.The seeds had strong dormancy characteristics,low germination rate and irregular seedling emergence in production,which severely restricted the large-scale artificial cultivation of Chinese antrum.The maturity of seeds collected from different harvesting sites was significantly different.In order to break through the bottleneck that restricts the deep development and commercial production of Heracleum moellendorffii Hance,the seeds collected in summer were divided into high maturity(average weight 12.5 mg)medium maturity(average weight 9.2 mg)and low maturity(average weight 6.1 mg)according to seed quality,which was followed by stratification,respectively.The differences of seed embryo development process,the dynamic changes of seed the embryo morphology and germination rate the main carbohydrate metabolism,the related enzyme activity,the biogenic analysis of key enzyme genes of glucose metabolism and their differential expression changed during stratification were systematically studied.It provides theoretical basis and technical support for the study of the dormancy and germination regulation mechanism and the promotion of the industrialization from the physiological and molecular levels of Heracleum moellendorffii Hance.The results show that:(1)During harvest,the embryo development stages of Heracleum moellendorffii Hance seeds with different maturity were mainly concentrated in two stages: heart-shaped embryo and torpedo-shaped embryo,and the proportion of heart-shaped embryo decreased with the increase of maturity.There were significant differences in seed embryo development with different maturity during stratification.(2)In the process of stratification,the seeds with high maturity showed the significant advantages in embryo development rate and embryo rate,and the germination rate was higher than that of medium and low maturity seeds.(3)During the stratification process,sucrose and starch contents increased slightly at first and then decreased rapidly.The contents of glucose and fructose decreased slowly at first,then increased slightly,and then decreased sharply.The changes of amylase and sucrase activities showed a trend of slow decrease at first and then a rapid increase;fructokinase activity showed a change trend of first slow increase,then a small decrease and finally a rapid increase.(4)The enzyme activities of amylase and sucrose synthase were decreased slowly at first and then increased rapidly.Fructokinase activity increased slowly at first,then decreased slightly,and finally increased rapidly.(5)At the end of stratification,the germination rates of seeds with high,medium and low maturity were 43.70%,34.90% and 28.41%,respectively.(6)Bioinformatics analysis of key enzyme genes showed that the amino acid length of the protein encoded by key enzyme genes was in the range of 301-808,the molecular weight was roughly in the range of 33241.96-93002.67 Da,the theoretical isoelectric point was in the range of 5.14-6.19,and the instability coefficient was in the range of 31.53-48.71,The aliphatic coefficient ranged from 62.67-99.13,all of which were stable hydrophilic protein.By constructing the evolutionary trees of the four proteins in different plants,and analyzing the characteristics of their domains and core motifs,the results showed that the four proteins had the same domain and core motifs arrangement in different species,indicating that they were highly conserved in evolution and performed similar functions.(7)With the increase of stratification time,the expression levels of Hm ACR12 and Hm SUS4 genes,Hm FRK1 gene and Hm PGIC gene in different maturity seeds showed a trend of "down-up","up-down-up" and "down-up-down ",among which the seeds with high maturity increased the first and decreased to the extreme value.The expression levels of Hm SUS4 and Hm FRK1 were consistent with their enzyme activities,while the middle and low maturity seeds were 20 d and 40 d later than the high maturity seeds,respectively. |
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