A Study Of The Coloration Substances Mechanism In The Red-leaved Mutant Populus Deltoids ’Quanhong’

"Quanhong"(Populus deltoids ’quanhong’), as a new red-leaf poplar varieties have received considerable attention for its highly ornamental value.But the studies on the coloration mechanism of the red-leaf poplars are very scarce, which delay the further development and utilization of foliage plant with Populus deltoids ’quanhong’ representative.Three basic kinds of pigments are found in the leaf of higher plants: chlorophyll, carotenoids and anthocyanins.The ratio of the three kinds of pigments and their distribution in the leaf determine the final colouration.In this study, to preliminarily investigate the physiological mechanism in ’Quanhong’, we discussed the synthetic changes of pigments and soluble inclusions, the seasonal dynamic changes of color value and the activities of enzyme in anthocyanidin biosyntheses, the influence of main meteorological factors on the expression of leaf color in ’Quanhong’ and Populus Linn 2025.The main results showed as follow.(1) The seasonal changes of each pigment contents in the leaf of Populus deltoids "quanhong’ showed the regular. Chlorophyll and carotenoids content maintained low in spring and autumn and increased in summer. In the contrast, anthocyanin content was lower in summer and higher in spring and autumn. In addition, the anthocyanin contents in the leaves of’Quanhong’were 9 times at least than that of Populus Linn 2025’, and the photosynthetic pigment contents were up to 2.2 times than Populus Linn 2025 during the study periods. Therefore, the results suggested that high foliar levels of Ant as well as the Chl/Ant balance play an important role in coloration in the leaf of’Quanhong’ poplar plants.(2) During the expression of leaf color in’Quanhong’, the relationships between the color value and anthocyanin content, and color value and anthocyanin/chlorophyll showed linear correlation. The color value well signs the color degreein’Quanhong’ poplar plants.So the color value will be selected as an important indicator used for the further breeding and evaluation of’Quanhong’superior strains.(3) Soluble sugar, soluble protein and anthocyanin contents changed similarly in the leaf of’Quanhong’, and sugar and protein were positively correlated to the anthocyanin synthesis. Therefore, we can infer that increasing the contents of soluble sugar and soluble protein was helpful to improve the aesthetic values in the cultivation and application of’Quanhong’poplar plants.(4) During the expression of leaf color in’Quanhong’, the dynamics changes of enzyme activities associated with anthocyanidin biosyntheses demonstrated that the relationship between PAL activity and anthocyanin content revealed a logarithmic curve and anthocyanin contents decreased when PAL activity increased, but the correlation between them was not siginificant. On the contrary, there were a significant linear relationship between CHI activity and anthocyanin contents and the anthocyanin contents increased with the increasing of CHI activitS.o CHI was regarded as the key enzyme in the anthocyanin biosynthesis of’Quanhong’leaf while not PAL.(5) Temperature、humidity and rainfall could together change the degree of the color values by their effect on anthocyanin contents or the ratio of anthocyanin and chlorophyll in the leaf of ’Quanhong’ toachevea different coloration goal in the leaves.