| Mallotus obongifolius(Miq.)Muell-Arg is a shrub or small tree of Euphorbiaceae,commonly known as Camellia oleracea Hegu tea and so on.It is a kind of tea beverage plant with Hainan eharacteristics and genuine medicinal plants.It has obvious anti-inflammatory,hepatobiliary,digestive,antigreasy,analgesic,antioxidant and other health effects and medicinal functions.It has a long history in Hainan folk.During the annual meeting of the Boao Forum for Asia in 2018,[Mallotus obongifolius(Miq.)Muell-Arg was selected as a national banquet tea product and was widely praised for its drinking and medicinal history.Germplasm resource is a precious Agricultural Heritage and a symbol of ecological civilization in a country or region.However,with the excessive exploitation and utilization,natural resources have been seriously damaged,making many ancient local varieties eliminated.Hainan[Mallotus obongifolius(Miq.)Muell-Arg is a wild germplasm resource with unique Hainan characteristics.Its leaf color,leaf type and its corresponding functions have attracted much attention.It is also a bottleneck affecting the development and large-scale popularization of Hainan partridge tea.In this paper,paraffin section and microscopy were used to study the cross-sectional anatomical structure of roots,stems and leaves of[Mallotus obongifolius(Miq.)Muell-Arg,and to explore its morphological structure and corresponding functional characteristics,so as to provide scientific basis for the development and utilization of[Mallotus obongifolius(Miq.)Muell-Arg in Hainan.The main results are as follows:(1)The cross-sectional anatomical structure of Mallotus peltatus(Geiseler)Mlill.-Arg.leaves from different populations is characterized by typical two-sided leaf structure,obvious stratification of upper and lower epidermis,thicker cuticle of upper epidermis and glandular hairs on upper epidermis of leaves.The palisade tissue and spongy tissue were obviously differentiated.The upper part of the palisade tissue was composed of long strip cells,and the lower part of the spongy tissue was composed of approximately circular cells.According to the morphological characteristics of leaves,the mean thickness of palisade tissue ranged from 41.335 to 16.777 um,the mean thickness of sponge tissue ranged from 87.884 to 26.712 um,the mean thickness of upper epidermis tissue ranged from 32.251 to 216.385 um,the mean thickness of lower epidermis tissue ranged from 25.235 to 9.420 um,and the thickness ratio of palisade tissue to sponge tissue ranged from 0.84 um.2-0.333,the variation range of leaf structure porosity was 0.550-0.311,the variation range of leaf anatomical structure compactness was 0.318-0.178,and the quantitative parameters of leaf anatomical structure were significantly different(P<0.05).Cluster analysis based on the quantitative parameters of leaf anatomical structure showed that 15 populations of Mallotus peltatus(Geiseler)Mull.-Arg.could be divided into four groups when the distance mapping was 10,namely:(Ⅰ),Ⅱ,Ⅱ).Class Ⅲ and Class Ⅳ).Clustering relationships among populations are closely related to their original habitats.the clustering results of quantitative index of leaf anatomical structure are basically reasonable,which can be used as an important auxiliary reference index for the population classification of Mallotus peltatus(Geiseler)Mull.-Arg.(2)The anatomical characteristics of cross section of Mallotus peltatus(Geiseler)Mull.-Arg.stem in different populations are as follows:the periderm of the stem is secondary protective tissue,located at the outermost layer of the stem,the cell shape is nearly rectangular,the fine gap is small,the arrangement is compact and the cell volume is small;the tissue adjacent to the epidermis is cortex,the number of cell layers is large,among which 2-4 layers of special cells are called sclerenchyma,which is special.The cells are located between the epidermis and the cortex.They can usually be dyed deep red by saffron staining solution.The remaining parenchyma cells vary from 4 to 6 layers.Contrary to the collenchyma,these cells have wider intercellular spaces and larger volume than the collenchyma.The vascular bundle tissue is located between the cortex and the stem pith cavity.It consists of primary xylem and primary phloem and is clearly separated by cambium.The medullary cavity is located in the middle of the stem and occupies a larger area than other tissues.According to the morphological characteristics of stem,we can quantify that the mean change range of epidermis thickness is 34.199-6.498 um,cortex thickness is 75.091 micron-42.697 micron,phloem thickness is 91.876 micron-34.542 micron,xylem thickness is 319.058 micron-46.291 micron,medullary structure thickness is 264.791 micron-101.087 micron,and stem lysis.Quantitative parameters of anatomical structure(epidermis,cortex,etc.)were significantly different(p<0.05).Cluster analysis based on quantitative parameters of stem anatomy showed that when the distance mapping was 5,15 populations of Mallotus peltatus(Geiseler)Mull.-Arg.could also be divided into four groups(Class Ⅰ,Class Ⅱ,Class Ⅲ,Class Ⅳ).Clustering relationships among populations are closely related to their original habitats.The clustering results of quantitative indexes of stem anatomical structure are ideal,which can provide some reference for the study of population classification of Mallotus peltatus(Geiseler)Mull.-Arg.(3)The cross-sectional anatomical structure and morphological characteristics of tea roots of Mallotus peltatus(Geiseler)Mull.-Arg.from different populations are as follows:periderm,parenchyma phloem and xylem.The peridermal tissue of Parrot Tea Root is closely arranged by multilayer cortical cells,with small intercellular spaces,long strips or rods,and uneven cell lengths.The columnar sheath is well developed,and the diameter of the catheter is large.It radiates outward in a radial manner.It has obvious phloem rays,which radiate outward parallel to the catheter.According to the morphological characteristics of roots,it was found that the mean changes of periderm thickness ranged from 26.623 to 6.545 microns,phloem thickness ranged from 100.449 to 27.438 microns,xylem thickness ranged from 586.176 to 126.236 microns,phloem ratio ranged from 0.498 to 0.074,and there were significant differences in quantitative parameters of root anatomy(periderm,phloem,etc.)(p The results of cluster analysis based on quantitative parameters of root anatomy showed that when the distance mapping was 8,15 populations of Mallotus peltatus(Geiseler)Mull.-Arg.could be divided into four groups(Class Ⅰ,Class Ⅱ,Class Ⅲ and Class IV).Clustering relationships among populations are closely related to their original habitats.the clustering results could be used as an indicator for the classification of Mallotus peltatus(Geiseler)Mull.-Arg.(4)There was a significant correlation between light intensity and soil moisture content of different populations and palisade structure of leaves and epidermis structure of stems of Mallotus obongifolius(Miq.)Muell-Arg(P<0.05),but there was no correlation with other tissue structures of roots,stems and leaves.(5)The results of comprehensive analysis show that the analysis of the cross-sectional anatomical structure of Mallotus obongifolius(Miq.)Muell-Arg can effectively provide theoretical support for the introduction and domestication of Mallotus obongifolius(Miq.)Muell-Arg,and also alleviate the over-harvesting of wild germplasm resources of Mallotus obongifolius(Miq.)Muell-Arg,so as to protect the wild germplasm resources of Mallotus obongifolius(Miq.)Muell-Arg. |
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