Study On Flavonoids Constitution And Physiological Characteristics Of Petal Color Expression Of Tree Peony Cultivars From Chinese Jiangnan Area

Tree peony is well-known in China. Flower pigments are the substantialbasis of the formation of peony color; Lipid peroxidation is one of the mainphysiological mechanism during blossom process of tree peony; Temperature,light, pH, metal ions are the external factors that influence the formation offlower color. Taking43cultivars of the four color series as test materials，therelationship between the flower pigment composition and flower color wasdiscussed. Physiological, biochemical and flower pigment composition variationcharacteristics were studied in blossom process of P. suffruticosa in order toexplore the flowering physiological regulation mechanism, provide theoreticalbasis for the coloring mechanism, and provide importment theoretical referencesfor prolonging florescence. The results were as follows:（1） The computer insisted technology was used to describe flower colorof Jiangnan tree peony according to the CIE color system. Wards minimumvariance cluster analysis was used to produce a d endrogram of43cultivars ofJiangnan tree peony, which indicated that all cultivars were divided in to fourgroups, white、 Pink、 Pink-Blue、 Reddish Purple. Significant positivecorrelationship between Chroma （C^*） and chromatic component a^*wasobserved in four color series, while the other CIE parameters displayedinconsistent correlationship among different groups. Notable negativecorelationship between Lightness （L^*） and a^*, L^*and C^*existed among thepink-blue and white cultivars, with the correlation coefficient0.618,0.629respectively, hower, the same CIELab characteristics displayed the oppositeamong pink and reddish purple cultivars, the correlation coefficient being0.589,0.606. No obvious negative correlation was obtained among pink and reddishpurple group （r²=0.156），and the pink blue and white cultivars demonstratelower positive corelationship（r²=0.436）. （2） Utilizing43cultivars of Jiangnan tree peony as materials, theflavonoids in the petals at full-bloom stage were analyzed and quantified throughUPLC-PDA and UPLC-Q-TOF MS. The results demonstrated the existence of15flavonoids in the petals, including4anthocyanins, seven flavones，fourflavonols. The main anthocyanins in the petals of Jiangnan tree peony werePn3G5G and Cy3G5G, and the main flavones/flavonols were Apigenin-hexoside, Apigenin pento-hexoside, Apigenin deoxyheso-hexoside andKaempferol di-hexoside respectively. Numerical analysis between flower colorand flavonoid composition revealed that the chemical phenotype of Jingnan treepeony pertained to PnCy, no significant correlationship between L^*、b^*andanthocyandins was observed while the content of Cy3G5G、 Pn3G5Gdramatically affect a^*. The more Cy3G5G existed in the vacuole, the redder theflower displayed. The factors that aroused color variation were considered to beQuercetin hexoside and Luteolin hexoside.（3） Utilizing pigment extraction solution of P. suffruticosa ‘Changhong’ asmaterial, several physicochemical factors such as light, heat, pH, metal ions weretested in order to elucidate their effets on the coloration. The results were asfollows:The color expression of anthocyandins of reddish purple cultivar was stableunder different temperatures although the absorbance value under532nmdeclined with the temperature arised, whereas incandescent lamp、sunlight、UVlight、 fluorescent lead the pigment color to shallow. The red color ofanthocyandins in ‘Chang Hong’ faded gradually and had a bathochromic shift ofλvis-maxas the increase of pH. Cu⁽2+0、Pb⁽2+0、Zn⁽2+0had remarkable influence onsolution of ‘Chang Hong’, and Pb⁽2+0caused a bathochromic effect on UVspectrum. White cultivar ‘Feng Dan Bai’ behaved inconsistently under differentmetal ions. Na+caused the absorbance data decline while other metal ions werepositive to absorbance under338nm.（4） With two color series of P. suffruticosa at different blossom stageschosen as material, the changes of active oxygen species （AOS） and relatedenzymes activities in petals during different blossom stages were studied. Theresults were as follows:Anthocyandins of two color series exhibited a similar tendency asflorescence process continued（i.e., Cy3G5G、Pn3G5G、TA amounting）and thecontent of Cy3G5G、Pn3G5G、TA of ‘Que Hao’ abounted significantly than ‘Xi Shi’. Aglycones of flavones and flavonols exhibited inconsistent trends betweenthe two. To ‘Que Hao’, the content of Lu、Ch declined while Qu、Is、Km、Ap、Tf amounted. To ‘Xi Shi’, the content of Lu、Ch amounted initially then declined,Qu declined yet and Km、 Ap、 Tf declined originally then ascendednevertheless.O2–· producing rate tendency of2cultivars was inconsistent, with P.suffruticosa‘Xi Shi’ increased at first, then decreased and rised again, while P.suffruticosa‘Xi Shi’ displaying the form of a bimodal curve; The content of H₂O₂of two color species showed up a tendency of increasing at first, then decreasing;With the passage of time, the content of the MDA and the production rate of theoxygen showed an upward trend in the P. suffruticosa. Changes of antioxidantenzyme activity of two color species performed in different trend during theflowering process. SOD、 PPO、POD activityof P. suffruticos‘Xi Shi’ amountedat first, then decreased and rised again, while ASA-POD displaying the form of abimodal curve; SOD、PPO activity of P. suffruticosa‘Que Hao’ displayed theform of a bimodal curve, and POD mounted at first, then decreased and rised again,CAT activity showed a similar tendency as the SOD of P. suffruticosa‘Xi Shi’.Further analysis showed that O2–· production and H₂O₂content were the keyfactors that affect the florescence stagement, which had obvious direct effect,putting on indirect effects through other factors on cell membrane lipid peroxide.POD was the main antioxidant enzyme of the late development, fluctuation rangeof each enzyme activity of the antioxidant enzyme system in the flowering was notobvious, all kinds of enzyme showed a good balance.