| Rhododendron mariae,belongs to Rhododendron subgen.Tsutsusi within the family Ericaceae,and is one of important ornamental and medical plants.Its leaves are medical main parts for use,and it is often confusable with that of the related species.In the present study,micromorphological characters of leaf epidermis were observed for 37 species in R.subg.Tsutsusi f For the purpose of the identification of the base source plants of R.mariae and its fakes,as well as genetic diversity of Rhododendron mariae is studied in order to provide the basis for selection and breeding of superior provenances.The plants of Rhododendron subg.Tsutsusi can be used as ornamental,and some species are used as medicine.The leaf epidermal micromorphological characteristics are of great taxonomic value in the subgenus,and it can also provide a theoretical basis for the identification of herbs in this subgenus since the leaf is the main raw material of the herb.However,the observation of leaf epidermis in this subgenus has not been thoroughly studied.In the present paper,micromorphological characters of leaf epidermis were examined for 37 species in Rhododendron subg.Tsutsusi using scanning electron microscopy(SEM),among which the relevant characters of 29 species are reported for the first time.The results reveal that:(1)The stomas are anomocytic and all on abaxial surface.(2)According to the morphological characters of glands,trichome types and stomatal apparatus of leaf epidermis,subgenus Tsutsusi can be divided into five types,i.e.,R.simsii-type,R.mariae-type,R.indicum-type,R.saxatiletype and R.farrerae-type.(3)The plants in R.simsii-type have the similar morphological characters,i.e.,virgate hairs,glands and stomatal apparatuses.(4)It is implied that the plants R.indicum-type have the close affinity with subg.Therorhodion in having distinct T-pieces at the polar region of guard cells.(5)R.saxatile-type differs from other types in its simple trichomes being virgate but not glands.(6)R.farrerae-type has glands only.(7)The relationships between the closely related species are also discussed on the basis of leaf epidermal features.(8)Micromorphological characters of leaf epidermis are of significant value for species delimitation in subg.Tsutsusi and TCD identification of Rhododendron mariae Hance.Rhododendron mariae Hance is distributed in south China with the distribution center in the Nanling Mountains and the surrounding areas,and has important values of ornamental and medicin.Ther genetic diversity of Rhododendron mariae Hance is studied by 36 individuals of13 wild populations using dd RAD sequencing data.The main results are as follows:(1)Based on dd RAD sequencing data,a total of 9080 SNPs were identified,and,it is implied that low genetic divisity within populations,high inbreeding coefficient,and high genetic differentiation among populations are speculated to be related to abundant rain during flowering season,and to be sensitive to environmental changes to not easy to expand.(2)The genetic structure of populations is consistent with the geographic distribution pattern,and it is divided into two lineages east and west,which are isolated by mountains of Daguishan-Darongshan-YunkaishanYunwushan-Tianlushan,and the genetic diversity of the eastern lineages was higher than that of the western lineages.(3)There is a significant connection between genetic distance and spatial distance,indicating that spatial isolation plays a great significant role in thegenetic differentiation of Rhododendron mariae.(4)The phylogenetic analysis implies that Rhododendron mariae is originated from the southwestern mountains and extended eastward along the Nanling Mountains,which is consistent with the previous predictions.(5)The population of LP and LN with high genetic diversity can be used for superior provenances.(6)It is suggested that the protection of wild populations of Rhododendron mariae should be mainly in situ conservation,supplemented by economic incentive mechanism protection,and ex situ conservation and introduction from YC populations with low genetic diversity. |
PDF Full Text Request