SCoT Genetic Diversity Analysis And Reproductive Biology Study Of Podocarpus

As a rare and ancient gymnosperms,Podocarpus is a good landscape tree with economic and medicinal value.In order to further understand the growth and development of Podocarpus and protect its germplasm resources,and lay a theoretical foundation for the future research and development of breeding improved varieties.In this study,experimental materials of Podocarpus were collected from guangxi university farm and jinsui floriculture in longan,guangxi.A new SCo T molecular marker was used to analyze the genetic diversity of 40 germplasm of 6 species of Podocarpus.At the same time,the reproductive biology of Podocarpus was studied by means of pollination and anatomical experiments.The following research results are obtained:(1)Sixteen SCo T primers were obtained by screening to amplify 40 species of Podocarpus germplasm.A total of 170 bands were amplified,among which 165 were polymorphic bands with a polymorphism ratio of 97.06%.The average PIC of 16 primers was 0.8863,showing high polymorphism.Therefore,it is considered that SCo T molecular marker is suitable for the study of genetic diversity of Podocarpus and has good polymorphism.(2)The observed value of allele(Na)of the six species of Podocarpus is between 1.3706 and 1.5353,and the effective value of allele(Ne)of the six species of Podocarpus is between 1.2193 and 1.2813.The genetic diversity index of 6 species was 0.3893,which was more than 2 times higher than that of0.1454,indicating that the genetic diversity of 40 species was relatively high,and the genetic differentiation and genetic diversity were mainly distributed among species.(3)P.makaii originated from Taiwan were clustered together with the P.costalis and P.costalis C.at the genetic similarity coefficient of 0.65.The genetic similarity coefficient of P.macrophyllus,P.wangli and P.princess from guangxi was about 0.70.The strongest genetic affinity was that of P.wangli and P.princess,with genetic consistency up to 0.8392 and genetic distance of 0.1753.Genetic similarity coefficient and principal coordinate analysis also get the same conclusion.(4)The pollen of P.macrophyllus is a typical pine pollen with round pollen grains and 2 air sacs.On the surface of the body,there were microwave granular texture of the cap and nodular cap margin,far mask granular and reticular texture of the germination groove,semicircular balloon with cavitation.The mean length of pollen was 40.502 m.The mean pollen length was 21.965 m.The average pollen height was 15.389 m.The pollen number of each microsporophyll obtained by hydrochloric acid dissolution method was48948.15±5256.27 grains.The viability of fresh pollen reached 82.28%.(5)The flower buds of male P.macrophyllus changed from single to3～5 clusters,and the flower buds differentiated from mid-early October to mid-march of the next year,and the flower buds were dormant from late December to late February of the next year.Flowering period for the next year from April to mid-may.The color of the spherules is from pale green to yellowish brown to green to yellow.The flower bud of the female cultivar of P.macrophyllus is always solitary,the flower bud is differentiated from early November to late march of the next year,the flower bud is dormant from late December to late march of the next year,and the fruit period is from late may to late July.Seed coat color by light green-gray green by white powder,seed color by pale green-green-red or purple.(6)The microsporangium wall of P.macrophyllus includes four parts:epidermis,chamber wall,middle layer and tapetum.The occurrence and development of the microspore include three stages: sporogenic tissue,meiosis of microspore mother cell and mononuclear microspore.Finally,the mononuclear microspores undergo three mitosis to form a 4-cell mature male gametophyte.The ovule of P.macrophyllus is composed of two parts: tepals and nucellus.The megaspore formation includes two stages: megaspore mother cell and functional megaspore.After free nuclear division,the female gametophyte matures,and the cell tissue is radiating honeycomb.