Altitude-related environmental factors shape the phenotypic characteristics and chemical profile of Rhododendron
Aims:Interactions between plants and the environment drive the diversity of plant phenotypes and secondary metabolites.Abiotic factors in the environment are known to vary with altitude,but it remains unclear how this variation affects plant characters and secondary metabolite composition,including whether secondary metabolites differ among different tissues and organs within a plant.Methods:We took samples of Rhododendron virgatum,R.decorum,and R.rubiginosum from three different altitudes.We measured environmental factors at each altitude,including temperature,relative humidity,and relative light intensity.We also measured vegetative traits,characteristics of plants'reproductive organs,and nectar features(nectar volume,sugar concentration,nectar components).We used UPLC-Qtof methods to analyze the levels and composition of secondary metabolites in the stems,leaves,petals,pollen,and nectar of populations from different altitudes.Results:As altitude increased,the temperature,relative humidity,and relative light intensity decreased.The heights,corolla sizes,and anther volumes of the sampled plants decreased significantly,while the branch diameters and pistil and stamen lengths increased significantly.The floral nectar volume and sugar concentration at the highest altitude(altitude C)were significantly higher than at altitudes A and B,the lowest and middle altitudes.The nectar sucrose content in Rhododendron was also significantly higher at altitude C than at the lower altitudes.The secondary metabolites of the Rhododendron samples did not differ significantly at different altitudes—at every altitude,the plants were dominant in flavonoids,steroids,terpenoids,phenylpropanoids,and alkaloids,and there were significant correlations among these components.However,the secondary metabolites did vary between different organs of the plants:nectar and pollen had significantly lower levels of metabolites than branches,leaves,and petals.Additionally,PCA results showed that Rhododendron plants at altitudes A and B were relatively similar in character and metabolites.It also revealed that the flavonoid components of plants at altitude C were different from those at altitudes A and B.Conclusion:Our results reveal a degree of adaptive variation in phenotypic characteristics and metabolite composition of Rhododendron plants at different altitudes.However,phenotypic traits vary much more than the composition and relative contents of secondary metabolites.We conclude that environmental factors present at different altitudes are much more likely to shape the external characteristics of plants than to change their internal metabolic profile.
Rhododendronaltitudeenvironment factorsphenotypic variationcomposition and content of secondary metabolites
万方数据
维普
