Study On Foliar And Pollen Micromorphological Characters Of Oolong Tea Germplasms (Camellia Sinensis)

The Oolong tea are a unique tea category of China.The foliar mircromorphology indicates adaptabilities of Oolong tea germplasms to their environment.The micromorphological characteristics of leaf genetic stability show genetic stabilities,and have taxonomic significances.Pollen,an angiosperm male germ cell,carries a large amount of genetic information and has a well-established taxonomic significance.In this study,the foliar and pollen micromorphological characters of 44 Oolong tea germplasms were observed by field emission scanning electron microscopy(FE-SEM).The evolutionary trends,genetic stabilities,and taxonomic significances of the foliar and pollen micromorphological characters of Oolong tea germplasms were analyzed.The main results were as follows:1、For the scanning electron microscope(SEM)observation of biological samples,the key to obtain original,detailed and ideal microscopic images is the appropriate sample preparation procedure.In the work presented here,the leaves of 3 tea varieties were tested by oven-drying,silica gel-drying and vacuum freeze-drying respectively.The results demonstrated that the both dorsal and ventral surface of the samples treated with oven and silica gel were strongly wrinkled.The stoma density and surface sculpture could not show the original morphological features.As for the test of vacuum freeze-drying,well preserved morphological characteristics were provided.Therefore,the vacuum freeze-drying is suggested as the preparation method for SEM.2、The foliar micromorphology of Oolong tea germplasms(Camellia sinensis(L.)O.Kuntze)was investigated by FE-SEM.The results showed that:The type of stomatal apparatus is oval.The trichome ornamentation are mainly long-stripe type,short-rods type and smooth type.The adaxial epidermal ornamentation are mainly ridging,wavy and flat.The cluster analysis showed that the trichome ornamentation and the adaxial epidermal ornamentation of Oolong tea germplasms from the same area show some common characteristics.Comparing the differences of foliar micromorphology between shrub and dungarunga,it was found that the stomatal density,trichome length and adaxial epidermal ornamentation are greatly affected by the tree shape.According to the drought-resistance analysis based on foliar micromorphology,the author found that Rougui have the strongest drought-resistance,while Taoren have the weakest drought-resistance.The foliar micromorphology of 44 Oolong tea germplasms have taxonomic significance.3、The pollen morphology of Oolong tea germplasmswas investigated by FE-SEM.The author found that the pollen grains of Oolong tea germplasms occur in monads.The grains are 3-lobed subspheroidal or 3-lobed subtriangular in polar view and oval,spindle-shaped,suboblate or subspheroidal in equatorial view.The exine ornamentations of the pollen are mainly verrucate,striate and multiporous.In addition,the aperture type is N3P4C5.The pollen of Oolong tea cultivars is of medium size.PCA and cluster analysis showed that the pollen morphology of Oolong tea germplasms from the same area show some common characteristics,as well as closer genetic distances.4、The foliar and pollen micromorphological characters of 20 tea cultivars were observed by FE-SEM.Comparing the differences between hybrid progenies and their parents,it was found that the trichome length and density of hybrids are decreased significantly.The adaxial epidermal ornamentation of hybrid progeny retains the ornamental characters of the parents.Comparing with the parents,the pollen sizes of the hybrid progeny are slightly smaller,the pollen shapes are more spherical.And the pollen apertures of the hybrid progens are closer to the poles.The changes of the foliar and pollen micromorphology may be more conducive for the tea plant to enhance its adverse resistance and be contribute to its own growth and reproduction.The ornamentation of leaves and pollen are more stable during variety selection and breeding,which can provide theoretical basis and micromorphological supplements for the classification and breeding of tea germplasms.