Studies On The Mechanism Of Carbohydrate Metabolism In Seeds Of Ginkgo Biloba L.

In this paper,the seed embryo and endosperm of Ginkgo biloba L.are used as the research object.The seeds of Ginkgo biloba L.are divided into 6 stages(5 embryo morphology after-ripening stage and 1 germination stage)according to the length of embryo development: Stage I : embryo long 0-0.3 cm;Stage II : embryo long 0.3-0.5 cm;Stage III :embryo long 0.5-0.8 cm;Stage IV : embryo long 0.8-1.0 cm;Stage V : embryo long >1.0 cm;Stage VI: seed germination(left open and right closed)The contents of internal storage material,enzymes related sugar metabolism and gene expression of sugar metabolizing enzymes in different stages are measured and analyze by high efficiency liquid chromatography,double wave method,kit method and RT-qPCR method The relationship between material metabolism and embryo elongation during the seed after-ripening and germination of Ginkgo biloba L.seeds are preliminarily understood.Expect to further reveal carbohydrate metabolism of the embryo after-ripening and germination process by exploring the difference between the material metabolism and enzyme activities in each part of the embryo and endosperm(Endosperm dip,Middle endosperm and Endosperm external)are preliminarily understood.To further reveal carbohydrate metabolism of the embryo after-ripening and germination process.The results are as follows:1.With the process of embryo elongation continuously until it reaches the fully mature embryo(Stage I-V),starch content of Ginkgo biloba L.endosperm decreases,starch content in endosperm increases during early germination stage(Stage V-VI).There are differences in the starch content of various parts of the endosperm during the seed after ripening.That is to say,the midlle endosperm> endosperm tip > endosperm external.The starch content in the embryo shows an upward trend in stage I-V and show an decline trend in stage V-VI.2.During the after-ripening period(Stage I-V),the soluble sugar content in the endosperm decreased with the maturity of the embryo,and the soluble sugar content in the embryo at the corresponding stage also increased.The starch content in the embryo and the endosperm is positively correlated with the soluble sugar content.It is speculated that the soluble sugars after hydrolysis of starch in the endosperm are used or transported,and the increased soluble sugars in the embryos may come from hydrolysis of the endosperm starch;after germination(Stage V-VI),the starch content in the endosperm rises,and the soluble sugar content continues to decrease.The content of starch in embryos begins to decrease,and the soluble sugar content decreased.This shows that the radicle breaks through the seed coatand the nutrient dependence in the endosperm decreases and it is mainly based on the temporary consumption of self-storage substances.3.The activity of β-Amylase in endosperm was higher than that of α-amylase during the after-ripening and germination of Ginkgo biloba L.seeds.The activity of β-Amylase increased firstly,and then began to drop abruptly after differentiation of embryonic organs(Stage III).β-Amylase plays a role in the main hydrolysis of starch;in the embryos,the activities of α-Amylase and β-Amylase are both at a low level,and there is an inefficient starch hydrolysis in the embryo.4.In the process of ripening and germination,the main soluble sugars in Ginkgo biloba L.seed are sucrose,fructose and glucose.There is a significant positive correlation between soluble sugar and sucrose in endosperm and embryo,indicating that the change of sucrose content is affecting soluble sugar.The main factors of content change,sucrose metabolism play an important role in the development of embryos;the glucose,fructose and β-Amylase activity in the embryo and endosperm are positively correlated(correlation coefficient>0.7),indicating that the endosperm,embryo in the embryo.Soluble sugars are directly linked to the hydrolysis of starch.5.The contents of sucrose,glucose and fructose are different in different parts of endosperm(endosperm tip,middle endosperm and outer part of endosperm),indicating that there are differences in the degree of sugar metabolism at each site.Synthetic enzymes(SS,SPS)has higher activity in the middle of endosperm,invertase(NI,AI)had higher activity in the tip of endosperm,and the net enzyme activity(difference between enzyme in the decomposition direction and enzyme in the direction of synthesis)of the embryo is generally negative.This indicates that the synthesis of sucrose in the embryo is the main sugar metabolism direction,and the endosperm is the opposite.6.The genes of neutral invertase,acid invertase and sucrose synthetase(GbNI,GbAI and GbSS genes)are expressed in all three stages of Ginkgo biloba L.embryos at the stages of after-ripening and germination.There was a significant difference between the after-ripening period(StageI-V)and germination period(Stage VI).After germination,the expression of various genes increases significantly while during the course of ripening(Stage I-V),the expression of GbNI and GbAI in embryos decreases progressively and synchronous with the change of NI and AI enzyme activity in embryos.The expression level of GbSS in embryos is higher than that of GbNI and GbAI,showing a gradually increasing trend.From the gene level,the relationship between sucrose metabolism and related enzyme activities is explained.