不同色彩珙桐苞片与叶片的生理特性研究

以生长在同一生境下的粉红珙桐和普通珙桐植株为试材，比较两种珙桐苞片/叶片的色素、基础代谢物含量和酶活性，探讨粉红珙桐苞片与叶片的呈色机理。结果显示：粉红珙桐叶片的类黄酮含量是普通珙桐的1.52倍，两种珙桐苞片中的类黄酮含量都较低，且无显著差异（P>0.05）；粉红珙桐苞片和叶片的花色苷含量极显著高于普通珙桐（P<0.01），分别是普通珙桐的1.68倍和3.67倍；粉红叶片的光合色素略低于绿色叶片，但无显著差异（P>0.05）。粉红珙桐苞片和叶片的可溶性糖、脯氨酸含量显著高于普通珙桐（P<0.05），可溶性蛋白含量则相反；苞片的可溶性糖含量极显著低于叶片（P<0.01），而可溶性蛋白和脯氨酸含量更高（P<0.01）。粉红珙桐苞片和叶片的苯丙氨酸解氨酶（PAL）、查尔酮异构酶（CHI）活性极显著高于普通珙桐（P<0.01），过氧化物酶（POD）和超氧化物歧化酶（SOD）活性无显著差异（P>0.05）；苞片中的酶活性大多都显著高于叶片（P<0.05），尤其是CHI活性。类黄酮、花色苷含量与可溶性糖、脯氨酸含量、PAL、CHI活性呈显著正相关，而与可溶性蛋白含量显著负相关。研究表明，花色苷是珙桐苞片转粉红的直接因素，而叶片转粉红受类黄酮和花色苷的共同影响，可溶性糖、可溶性蛋白、脯氨酸、PAL、CHI影响花色苷的合成。

Physiological Characteristics of Davidia involucrata Bracts and Leaves with Different Colors

To explain the coloration mechanism of pink Davidia involucrata Baill., D.involucrata bracts and leaves with two different colors were selected to study the physiological indexes including pigment, basal metabolite content and enzyme activity. The flavonoid content(FC) of pink leaves was 1.52 times that of green leaves. Flavonoid contents in two colors of bracts were low, and the difference was not obvious(P>0.05). The anthocyanin contents(AC) in the bracts and leaves of pink plants were 1.68 times and 3.67 times that of common ones, and the difference was extremely obvious(P<0.01). The photosynthetic pigment contents of pink leaves were slightly lower than that of green leaves(P>0.05). Compared to common plants, pink ones accumulated more soluble sugar(SS) and proline(Pro) but less soluble protein(SP)(P<0.05). Compared to the leaves, the bracts accumulated less soluble sugar(SS) but much more proline(Pro) and soluble protein(SP)(P<0.01). The activities of phenylalanine ammonia-lyase(PAL) and chalcone isomerase(CHI) of pink ones were significantly higher(P<0.01), while peroxidase(POD) and superoxide dismutase(SOD) activities in two colors of plants were not much different(P>0.05). The enzyme activities of the bracts were mostly higher than that of the leaves(P<0.05), especially the CHI activity. The contents of flavonoid and anthocyanin were significantly positively correlated with soluble sugar, proline contents, PAL and CHI activities, but negatively correlated with soluble protein content. In conclusion, anthocyanin directly caused the bracts to turn pink, and flavonoid and anthocyanin caused the leaves to be pink. Soluble sugar, soluble protein, proline, PAL and CHI affected the anabolism of anthocyanin.