Mechanism Of Chilling And Concentrations Of Gibberellic Acid On The Epicoty Germination In Paeonia Ostii

Paeonia ostii is a famous medicinal and ornamental peony in China.Its dried root bark is a valuable medicine.P.ostii seedling has developing roots and strong resistance.It is also a common bickiron of ornamental peony.P.ostii is a major oil producing peony varieties because of its high seed yield.However,P.ostii seeds have a deep dormancy trait.The winter naturally chilling can break its epicotyl dormancy and germinate into seedlings.It lasts about 6 month from seeding to planting,which restricts the seedling production rate seriously The number of seedlings far failed to meet production needs peony seed oil.Currently,there are two commonly methods:chilling treatment(physical method),and GA treatment(chemical method)used to break dormancy hypocotyl of P.ostii seed.There are significant differences in the growth state of the seedlings between the two methods.But the physiological mechanism is not clear.In this research,we selected optimal treatment on break hypocotyl dormancy based on the laboratory and previous findings:chilling temperature treating 27 days and 300 mg L-1GA3 soaking 24 hours.We researched the contain substances change in the seeds of P.ostii during the feeling chilling process and the difference on epicotyl development in physiological and biochemical characteristics of P.ostii seed between chilling and GA3 treatment.In order to provide a scientific basis for access to robust seedlings P.ostii quickly.The main results are stated as below:1.The contain substances change in the seeds of P.ostii during the feeling chilling processUsed the year harvested mature seeds of P.ostii as experimental material.In warm stratification until the seed root up to 4cm,We set artificial hypothermia 27 days treatment to break epicotyl dormancy,and studyed the physiological metabolic changes inside the seeds of P.ostii during chilling processing(3,10,18,27 d).With the time extent,the starch content increased and reached maximum content until the end of the treatment compared to CK.The soluble sugar content increased and increased largest during 3-10,increase slower later.The soluble protein reduced in the seed embryo on chilling treatment.The three concentrations are decreased in the endosperm.Starch content is continuing to decline,while the soluble sugar content was elevated in 3-10 days,after which the state has been declining,the soluble protein content has dropped more slowly,But overall levels did not change significantly,Because of these three substances plays an important role in form in seed construction process of P.ostii.The physiological metabolism changed slowly of seeds in this phase.Therefore changed no hypocotyl shape of seed.Four kinds of endogenous hormones(ZR,IAA,ABA,GA)were changed in content during the process of feeling chilling:ZR content increased?IAA content increased?ABA content decreased?GA content increased in the seed embryo.ZR content decreased,IAA content increased,ABA content decreased,GA content increased in the endosperm.The four hormones play synergistic effects on hypocotyl dormant of P.ostii.Promote seed germination.But in this time the seed morphology did not change,further experimental observation are required on subsequent germination and growth conditions of P.ostii.2.The difference on epicotyl development in physiological and biochemical characteristics of P.ostii seed between chilling and GA3 treatment.We observed and compared the two treatment:chilling temperature for 27 days and 300 mg L-1 GA3 soaking 24 hours on affecting the seed subsequent growth simultaneously.The results showed:both treatment can effectively break the hypocotyl dormancy on the seed of P.ostii,shorten epicotyl germination time.But the seeds are vary in shape between the chilling treatment and GA3 soaking.The seeds'hypocotyl are round and thick,but the cotyledons grow slowly on chilling treatment.The seeds' hypocotyl are elongated and flattened,cotyledons grow faster,endosperm utilized efficiently on GA3 soaking.The two treatments have improved the embryo starch and soluble sugar content,decreased soluble protein content.Starch content increased in the range of 3-8 days maximum,soluble sugar content also increased the magnitude of the largest in 3-8 daysThe nutrients and endogenous hormone levels are affected by the both two treatment in embryo and endosperm.The contains increase slower later.Soluble protein content declined largest in 3-8 days.Both treatments reduced the levels of these three substances in the endosperm,and starch and soluble sugar content reduced largest in 3-8 days.The overall soluble protein declined more slowly.Meanwhile,two kinds of processing in the embryo and endosperm effectively improved promote hormone(ZR,IAA,GA)content,reduced the inhibiting hormone(ABA)content.The indicators on post-processing of chilling are better than GA3.It can infer that chilling treatment can make the seed of P.ostii more potential on the following growth3.The differences on protein components during epicotyl dormancy breaking of P.ostii between chilling and GA3 treatment.The difference expressed proteins would exhibit different functional during the different stages of seed development process.The results between chilling treatment for 27 days at 4? and 300 mg L-1 GA3 soaking for 24h in seed embryo and endosperm on protein gel electrophoresis showed:in the test of SDS-PAGE gel electrophoresis.There were six different protein expression in the embryo between chilling treatment and GA3 soaking,their molecular weight between 60-80 kDa,30-40 kDa,20-30 kDa,12-20 kDa.There were five different protein expression in the endosperm between the chilling treatment and GA3 soaking,their molecular weight between 50-60 kDa,30-40 kDa,20-30 kDa.The expression of these differences in protein processing may be an important factor to lead different pace of time on seed epicotyl dormancy breaking.But what is the specifical molecular weight of the protein require to do follow-up experiments.