Study On Genetic Diversity Of The Plus Trees Of Sapium Sebiferum

The Sapium sebiferum seeds collected from Hunan, Guangdong, Anhui and other places were sow, cultivated and analyzed the genetic diversity of Sapium by morphological markers and molecμLar level. The growth characteristics were measured, and by means of ISSR marker, the DNA diversity of plus plants from six superior popuLations were analyzed with leaves as material. So as to establish ISSR-PCR reaction system of sapium, and the genetic variation and differentiation within populations and species were discussed, which provide a theoretical basis for the excellent resource selection of sapium. The main results are as follows:(1)There were great discrepancies among different plus plants in seed traits and their seedlings’s height and diameter growth. Based on the annual growth characterstics, the growth period of seedlings was classified into4stages.21were elected to optimal plant according to oil content of seeds and growth status of seedlings.(2)The single factor and orthogonal design was used to setup ISSR-PCRreaction system, and the suitable PCR system (20μL) was established as follows:3.0mmol/L Mg2+,0.35mmol/L dNTP,0.7umol/L primer,2.5U Taq DNA polymerase,75ng template DNA and2μL10×buffer (Mg2+free), annealing temperature of50～56℃.(3)10primers were screened to research the genetic structure about the32samples of sapium. A total of118polymorphic loci were amplified and125alleles were detected using ten primers, the ratio of94.40%showed the rich genetic diversity of sapium.(4)The data analyzed by the PopGen32software revealed that the effective allele (Ne) was1.4731, genetic diversity index (H) was0.2822and the Shannon’s information index (I) was0.4321, which has a high genetic diversity at the species level. Genetic diversity (Ht) of superior sapium groups was0.2586and Hs within the group was0.1450, the coefficient of genetic differentiation (Gst) was0.4395, the variation within species accounted for43.95%and among species accounted for56.05%, which suggested that the variations exist within populations and species.(5) The correlation of clustering and provenance was not significant by UPGMA clustering of different populations.Genetic similarity coefficient of superior sapium was0.368～1.000by NTSYS software analysis which indicated3#and6#,20#and21# were the closest genetic relationship and the superior that was close to21#have better conditions on species, but needed to adapt in time and space. The clustering diagram of genetic relationship about32sapium sample which showed that genetic variation within populations are abundant and there was no significance of correlation between genetic and geographical distances were structured, and can be divided into3groups.