Study On The Physiological And Biochemical Characteristic During The Seed Germination Of Paris Polyphylla Var. Yunnanensis

Paris polyphylla var.yunnanensis is traditional medicinal materials of China,which is one of the original plants ruled by《Pharmacopoeia of China(2010)》.It is mainly distribute in Yunnan,Guizhou and Sichuan.The demand for P.polyphylla var.yunnanensis is on the increase for its many efficacies to human,such as clearing away heat and toxic materials,eliminating swelling and alleviating pain,and arresting convulsion and cooling hepar.For its morphophysiological dormancy,the seed of P.polyphylla var.yunnanensis can germinate after two winters and one summer.The long germination period of the seed makes the growth period P.polyphylla var.yunnanensis long.The existing drug source of P.polyphylla var.yunnanensis is far from meeting the market demand for its depleted wildlife resources.In order to break the seed dormancy and shorten the period of the seed germination,it is necessary to know the physiological and biochemical characteristic changes during the seed germination of P.polyphylla var.yunnanensis.In order to explore the mechanisms of P.polyphylla var.yunnanensis seed dormancy,the law of the anatomical structure,differentiation and development,the content of endogenous hormone,the content of nutritive substance were studied and the enzyme activity were studied.The main conclusions are as follows:1.According to the results of the anatomy,the seed germination process is divided into seven stages.Embryo is an oval in the initial stage of the freshly picked seeds,the embryo only develops partially and the length was 9.58% of the endosperm.After the seeds were stratified for 42 days,embryo began to swell and embryo rate increased rapidly.Showing that the seed was becoming a breaking dormancy state from a dormant state.15 days of the stratification,seed imbibition was obvious,but the seed coat didn’t appeared cracks,the results showed that the seed coat didn’t block seminal sopping.2.During the process of seed germination,abscisic acid(ABA)content reduced from 54.34 ng/g.FW to 32.16 ng/g.FW,gibberellin(GA)and zeatin riboside(ZR)content increased gradually as a whole.As the extension of stratification time,ABA content in the dormant seed was reduced,GA content and the ratio of GA/ABA was rised continuely,but the still significantly lower than that in the germination seed(p < 0.05).The results suggesting that reducing ABA content alone may not be enough to release the dormancy of Paris polyphylla var.yunnansensis during seed germination,it may be able to release seed dormancy and promote the development of embryo effectively by increasing of GA content and the GA/ABA ratio.The correlation analysis showed that the endogenous hormone content and ratio was significantly correlated with the embryo growth(p < 0.05),the impact of GA/ABA ratio on embryo is the largest.3.After the seeds were stratificated,β-amylase was activated at first,it breaked down starch to sugar for breath.With the extension of stratification time,α-amylase activity raised,the sugar content raised,the POD and CAT activity improved continuously and they reduced after seed germination.The results showed POD and CAT play an important role on clearing oxygen and H2O2,creating favorable conditions for seed germination.4.At the first stage of the stratification,sugar content reduced about 67%,the starch content and soluble protein contents added about 9% and 48% respectively.The results show that the seeds were hastening its after-ripening processes in the first stage of the stratification.starch content in the dormant seeds of the same stage is significantly higher than gemmiferous seeds,but there were no significant differences of the sugar content among them.The results showed that the sugar was not used as substrates of the respiration,the low respiratory rate is the reason of the seed dormancy.5.The POD was significantly and positively correlated with the CAT(P<0.01,r=0.6343),the results showed that there was a synergy between the two enzymes to eliminate free radicals.The starch content was significantly and positively correlated with the embryo rate(P<0.01,r=-0.8447).The results showed that starch was the main nutrient during the seed germination,it offered substances for seed germination.There was a positively correlated between POD and GA,SOD and IAA,β-amylase and GA,IAA,ZR.The starch content was significantly and positively correlated with the four hormones content.The results showed that the hormones as signaling molecules played an important role in modulating enzymatic activity the hormones as signaling molecules played an important role in modulating enzymatic activity and stimulating nutriment.