Reasons Of Leaf Color Changing In Malus Sieboldii

Malus sieboldii is a kind of plant with great ornamental value for its abundant colors in autumn.The study was performed to study the change of pigment content in leaves of Malus sieboldii during autumn,and to provide the theoretical basis for leaf color improvement and breeding of garden tree species.Green,yellow and red leaves of Malus sieboldii with obvious difference in leaf color were taken as experimental materials.The species and content of pigments were detected by UV photo-spectrometer and HPLC-DAD.,relevant causes of leaf color change was analyzed afterwards.(1)The experimental results indicated that the main pigments in the leaves of Malus sieboldii were chlorophyll,carotenoid and anthocyanin.The major anthocyanin contained in the leaves was the Cyanidin-3-galactoside.Meanwhile,there were mono-phenols such as proanthocyanidins B1,rutin and chlorogenic acid in the leaves of Malus sieboldii.As auxiliary pigments,mono-phenols were found to play a supporting role in the fineness of leaves.Furthermore,the total flavonoids content(from high to low)were red,yellow and green in three species of leaves of Malus sieboldii.The anthocyanin content in red leaves was higher than that in other leaves,moreover,anthocyanin percentage in red leaves was higher than that of chlorophyll and carotenoids proportions.The carotenoid content in yellow leaves was relatively high,and the proportion of anthocyanin and chlorophyll ranked between the other two species.The leaf color changes of Malus sieboldii in autumn is achieved under the combined action of many factors,and the most direct reason is the changes of pigment content and proportion.(2)Seven structural genes were expressed in Malus sieboldii,but the expression was different.It indicated that the synthesis of anthocyanins was influenced by the expression of structural genes,not by the gene expression.(3)The express of genes CHS,FGT,DFR and ANS that was related with red leaf flavonoids synthesis pathway was significantly higher than that of green and yellow.At the same time,the content of anthocyanin that was detected in red line was also higher.The FLS gene expression in the red line was 5.04 times higher than that in green line,while the amount of Rutin in the red was 1.40 times higher than that in green line.The results showed that the content of related products in the red line was improved with the increase of structural gene expression in the synthetic pathway of flavonoid.