Ecological Anatomical Characteristics And EST-SSR Molecular Marker Development Of Tigridiopalma C. Chen

Tigridiopalma C.Chen is an endemic genus in China,and its distribution range is very narrow.At present,the natural distribution of T.magnatica C.Chen and T.exalata S.J.Zeng,Y.C.Xu & D.F.Cui populations are only found in Guangdong.Taking T.magnatica in Guigang town in Yangchun,Magui town in Gaozhou,Guding town in Gaozhou,Ehuangzhang Provincial Nature Reserve in Guangdong,Yunkaishan National Nature Reserve in Guangdong and T.exalata in Longmen County in Huizhou,Guangdong as the research objects,the plant materials of Tigridiopalma from different populations were collected,and the carbon and nitrogen isotopic contents of T.magnatica and T.exalata were determined,The vegetative organs of T.exalata were dissected,and EST-SSR primers were developed by using the transcriptome data of T.exalata.The contents including carbon and nitrogen isotopic composition,anatomical structure characteristics,genetic diversity,genetic differentiation and genetic structure of Tigridiopalma were discussed.The main results are as follows:(1)The anatomical characteristics of the roots,stems and leaves of T.exalata reveal that Tigridiopalma adapts to the shady,humid and steep environment,but not to the arid and cold environment.The root xylem of T.exalata is developed,and the root surface is covered and protected by velamen,so that it can grow on steep stone walls.The epidermis of the stem is thin,the cuticle outside the epidermis is not obvious,and there are a large number of parenchyma cells rich in water and nutrients in the stem,indicating that T.exalata does not adapt to the arid and cold environment.Mesophyll tissue did not differentiate into palisade tissue and sponge tissue,showing adaptability to shade and humid environment.(2)By analyzing the composition characteristics of major elements C and N and stable isotopes (13)~C and (15)~N in roots,stems,leaves,rhizosphere soil and rocks of Tigridiopalma in various regions of Guangdong Province,it is found that Tigridiopalma tend to assimilate more (12)~C and (14)~N and absorb less (13)~C and (15)~N.Moreover,the element composition of T.magnatica and T.exalata is very close,so it is difficult to distinguish the two plants by the content of C and N and the value of ?(13)~C and ?(15)~N.(3)16 pairs of polymorphic EST-SSR primers were developed by using transcriptome data,and the genetic diversity,genetic differentiation and genetic structure of 14 populations of T.magnatica and T.exalata were analyzed by using polymorphic primers.The results of genetic diversity analysis showed that the genetic diversity of T.exalata population was higher than that of T.magnatica population,but the genetic diversity of each population of Tigridiopalma was low.The results of genetic differentiation analysis showed that there was a great genetic differentiation between T.magnatica and T.exalata,and the genetic differentiation among T.magnatica populations was greater than that among T.exalata populations.UPGMA cluster analysis and principal component analysis(PCA)divided the two different populations of T.magnatica and T.exalata into two categories,among which the T.magnatica populations located in Yangchun,Gaozhou and Xinyi were clustered into one category,while the T.exalata populations collected from Longmen,Huizhou were also clustered into one category,indicating that the EST-SSR primers developed in this study can be used for the analysis of interspecific genetic relationship.The anatomical results of the vegetative organs of T.exalata explain the reason why Tigridiopalma have strict requirements on the living environment from the level of physiological structure,and provide a theoretical basis for the conservation,development and utilization of Tigridiopalma.The results of genetic diversity research show that the genetic diversity of Tigridiopalma is at a low level,its population has insufficient evolutionary potential and is difficult to resist the adverse effects of environmental changes.It is suggested to adopt the protection strategy of both on-site protection and ex situ protection for T.magnatica and T.exalata.At the same time,publicity should be strengthened to improve the protection awareness of local residents and reduce man-made interference and damage.