Variation Of Flavonoid Content In Taxus Cuspidata Seedlings And Its Responses To Environmental Factors

Plants form a defense system that responds to environmental change during evolutionary adaptation.Flavonoids,as vital secondary metabolites in plants,are important indicators of plant chemical defense capability in the defense system.In this study,three-year-old seedlings of Taxus cuspidata from five sources were transplanted to four sites(37°N-43°N).The flavonoid content in the leaf epidermis of T.cuspidata seedlings was determined by Multiplex-3(Force-A,France)non-destructively.The flavonoid content in the leaf epidermis of T.cuspidata seedlings change patterns with latitude and its responses to environmental factors of the test sites and sources were analyzed.At the same time,the seedlings were potted and controlled the light intensity and water content of soil respectively.The responses of flavonoid content of three-year-old and five-year-old T.cuspidata seedlings to different light intensity and soil water content were studied.The relationships between flavonoid content and total biomass,growth and photosynthetic rate of T.cuspidata seedlings were respectively analyzed.The aim of this study was to to analyze how T.cuspidata seedlings adjust their flavonoids to adapt different environments.The conclusions are as follows:(1)The flavonol index(FLAV)and anthocyanin index(ANTH)of T.cuspidata seedlings decreased with the increase of latitude in the test sites.(2)The relative contribution rate of environmental change in the test sites to the changes of FLAV and ANTH of T.cuspidata seedlings was higher than that of environmental change in the sources and the interaction effect between the test sites and the sources.The explanatory rates of climate factors in the test sites on FLAV and ANTH(49.8%,55.4%)were higher than those of climatic factors in the sources(35.3%,29.2%).The environmental change in the test sites played a leading role in driving thechange of flavonoid content in T.cuspidata seedlings.(3)The results of variation partitioning of climate factors in different test sites indicated that illumination had the highest explanation rate for the changes of FLAV and ANTH.The results of variation partitioning of climatic factors in different sources revealed that water-related factors had the highest explanation rate for the changes of FLAV and ANTH.(4)The FLAV and ANTH of T.cuspidata seedlings in three and five years old increased with the increase of light intensity.The increase of light intensity was beneficial to the increase of flavonoid content in T.cuspidata seedlings.The FLAV and ANTH of T.cuspidata seedlings in three and five years old increased first and then decreased with the decrease of soil water content.The accumulation of flavonoids in T.cuspidata seedlings was related to the degree of drought stress.Excessive drought stress was not conducive to the increase of flavonoid content in T.cuspidata seedlings.(5)Under the control of light intensity,there was a significant negative correlation between ANTH and total biomass of five-year-old T.cuspidata seedlings(P<0.05).Under the control of soil water content,there was a significant positive correlation between FLAV and net photosynthetic rate of five-year-old T.cuspidata seedlings(P<0.05).