Study On The Mitigation Effect And Mechanism Of Three Exogenous Substances On The Drought Stress In Paeonia Ostii

The oil tree peony is a unique woody oil crop in China.It has attracted much attention because the content of unsaturated fatty acids in its seed oil is higher than 90%,especially the α-linolenic acid which is rich in up to 41%.Paeonia ostii(P.ostii)was an oil tree peony resource approved by the Ministry of health of the People’s Republic of China.It has been widely planted in more than 20 provinces and regions of China,especially in arid or semi-arid areas such as mountainous areas and sandy wasteland,because of its advantages of being ornamental,easy to survive,large amount of seed setting and high content of unsaturated fatty acids.In these areas,drought is an environmental factor that seriously hinders the growth and development of P.ostii,and how to alleviate the restriction of drought stress on the growth and development of P.ostii is a problem that needs to be solved urgently in current production.Therefore,this study started with the regulation of exogenous chemical substances and genetic regulation respectively.On the one hand,three exogenous substances,including ferulic acid,fulvic acid and graphene oxide were used to treat with P.ostii,and related indicators were measured after natural drought.The alleviating effect and related mechanism on P.ostii under drought stress were discussed.On the other hand,the P.ostii fructose-1,6-bisphosphate aldolase gene(PoFBA)was cloned,and its drought tolerance function was verified by genetically modified tobacco.The main results were as follows:(1)Ferulic acid treatment could alleviate the wilting symptoms of P.ostii leaves under drought stress,reduce leaf water loss,inhibit the accumulation of superoxide anion(O2·-)and hydrogen peroxide(H2O2);reduce relative conductivity(REC)and proline(Pro)content;increase antioxidant enzymes activities such as superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and ascorbate peroxidase(APX);increase net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),transpiration rate(Tr),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(Y(Ⅱ))and non-photochemical quenching coefficient(qN),reduce the initial fluorescence(Fo);reduce the damage of drought stress to the leaf cell structures and increase the expression level of drought-tolerance related genes at the same time.(2)Fulvic acid treatment could also alleviate the wilting symptoms of P.ostii leaves under drought stress,reduce leaf water loss,inhibit the accumulation of O2·-and H2O2;reduce REC and Pro content;increase antioxidant enzymes activities such as SOD,CAT,POD and APX;increase Pn,Gs,Ci,Tr,Fv/Fm,Y(Ⅱ)and qN,reduce Fo;reduce the damage of drought stress to the leaf cell structures and increase the expression level of drought-tolerance related genes at the same time.(3)Firstly,graphene oxide treatment could reduce soil water loss in different layers without changing soil pH value;Secondly,graphene oxide treatment could alleviate the wilting symptoms of P.ostii leaves under drought stress,reduce water loss in roots,stems and leaves,inhibit the accumulation of O2·-and H2O2;reduce REC and Pro content;increase antioxidant enzymes activities such as SOD,CAT,POD and APX;increase Pn,Gs,Ci,Tr,Fv/Fm,Y(Ⅱ)and qN,reduce Fo;reduce the damage of drought stress to the leaf cell structures and increase the expression level of drought-tolerance related genes.In addition,no graphene oxide was detected in P.ostii.(4)The full-length cDNA sequence of PoFBA was cloned by RACE amplification technology.The transgenic tobacco and wild-type tobacco were subjected to natural drought stress,and it was found that compared with the wild-type tobacco,the wilting degree of transgenic tobacco leaves was lower,the accumulation of O2·-and H2O2,REC and Pro content were all less;the antioxidant enzyme activities such as SOD,CAT,POD and APX were higher;the activities of fructose-1,6-aldolase diphosphate(FBA)and ribulose diphosphate carboxylase/oxygenase(Rubisco),starch content,Pn,Gs,Ci,Tr,Fv/Fm,Y(Ⅱ)and qN were significantly higher,the expression level of genes related to the control of photosynthetic rate and the promotion of ribulose diphosphate(RuBP)regeneration was higher.