Analysis Of Anthocyanin Composition And Color Factors In Three Species Of Bauhinia

Bauhinia variegata,B.purpurea and B.blakeana are belonging to the genus Bauhinia of Caesalpiniaceae,which are one of the important woody flowers in south of the Five Ridges,and the color is one of its important ornamental properties.In this study,the petals of Bauhinia variegata,Bauhinia blakeana and Bauhinia purpurea were used as materials,and the phenotypes of flower color were measured by Colorimetric card and colorimeter,and the content of pH,soluble sugar and soluble protein in petals were measured by pH meter anthrone colorimetry and Coomassie brilliant blue G-250 method,and the composition and content of anthocyanins were analyzed and determined by chemical coloration and ultraviolet spectrophotometry,and observation of the tissue structure of petals by tissue section method,in order to understand the reasons of flower color formation in cytochemistry and morphology,it can lay a foundation for the breeding and classification of three new flower varieties of Bauhinia.The main findings are as follows:?1?Phenotypic measurement of flower color:There is an extremely significant negative correlation between luminance and redness of Bauhinia variegata with different colors,that is,with the red degree will be low,the brightness of the flower color is getting higher and higher;L*has no significant correlation with b*of Bauhinia variegata with different colors.There is a very significant positive correlation between the value of L*and the blue degree b*?negative number?of Bauhinia purpurea with different colors,that is,with the increase of blue degree,the luminance of petals becomes lower and lower;L*has no significant correlation with a*of Bauhinia purpurea with different colors.In the whole flowering process of Bauhinia variegata,the brightness of petals is getting higher and higher,and the red gradually melts;the blueness of petals increased gradually from bud stage to late blooming stage,and suddenly decreased from late blooming stage to decaying stage.?2?Physiological and biochemical Indexes of petals and Color of Flowers:The luminance?L*?of the petals of Bauhinia variegata decreased with the increase of vacuolar acidity and the contents of total flavonoid,total anthocyanins and soluble sugar;the red degree?a*?of petals increased with the increase of anthocyanin content,soluble sugar content and the acidity of petals;blue?b*?decreased with increasing soluble sugar content;and the main factors that cause the color diversity of Bauhinia variegata are the anthocyanin content and the ph of the petals vacuole.The luminance of the Bauhinia purpurea petals decreased with the increase of anthocyanin and soluble sugar content;the redness?a*?increased with the increase of soluble protein,anthocyanin and total flavonoids in petals and the enhancement of vacuolar acidity;The blue degree?b*?increases with the increase of anthocyanin and soluble sugar content.During the flowering process of Bauhinia variegata,with the decrease of vacuolar acidity and anthocyanin content,the flower color is getting brighter and brighter;with the decrease of anthocyanin content,petal red gradually decreased and faded.?3?Preliminary analysis of anthocyanins from three species of Bauhinia variegata:All flower petals of the three species contain no chlorophyll or carotenoid,but all contain flavonoids,all flowers contain anthocyanins except for the white flowers of the Bauhinia variegata and the Bauhinia purpurea.All colors of three species do not contain dihydroflavone alcohol and phenolic hydroxyl group,and all of them contain o-diphenol hydroxyl group.With the exception of"purple"and"powder"of Bauhinia variegata,the other flowers and colors all contain flavonoids.Pink and white Bauhinia purpurea and"white","powder-"and"powder"of Bauhinia variegata do not contain chalcone or orange ketone.?4?Microscopic observation on the tissue structure of petals of three species:There is no pigment accumulation in the petals of Bauhinia acuminata var.candida,its petals appear white because the incident light shines on the epidermal cells of the petals and is refracted many times.The red pigments of the three species were only distributed in the upper and lower epidermis of the petals,but not in the sponge and palisade tissues.Compared with three kinds of Bauhinia remaining flat petal epidermal cells,petal epidermal cell shape Bauhinia variegata"purple+"conical,deepened the petal color.?5?The effects of temperature,light and metal ions on the color of anthocyanins of different flower colors of three species of Bauhinia were studied in vitro:When the temperature ranges from 4?to 60?,the thermal stability of the Bauhinia acuminata var.candida and white and pink flower of the Bauhinia purpurea anthocyanins is excellent;and when the temperature is above 40?,the remaining anthocyanins of the three species begin to degrade with the increase of temperature.The photostability of the Bauhinia acuminata var.candida and white and pink flower of the Bauhinia purpurea anthocyanins under fluorescent lamp is excellent;and the light stability of the other flowers was poor,with the increase of light time,anthocyanin continued to degrade.The concentration of 0.1%Na⁺?Ca²⁺?Pb²⁺?K⁺?Mg²⁺?Cu²⁺has a destructive effect on the white,purple,red and red+anthocyanin structure of Bauhinia variegata,but it has no obvious effect on the anthocyanidins of pink,deep pink Bauhinia purpurea and Bauhinia blakeana.Fe³⁺can increase the anthocyanin color of Pink Bauhinia purpurea.