Study On Genetic Diversity Of The Plus Trees Of Swida Wilsoniana

Swida wilsoniana is a kind of wild species woody oil plant which the oil can be produced biodiesel. It is mainly distributed from the yellow river basin to the hill lands of Southwest areas. Although many researchers had done much more research on Swida wilsoniana, there still was no report about the genetic diversity appraisal of the plus trees of Swida wilsoniana in natural distribution region.Genetic diversity is base of variation of the species, while the variation embodies the genetic diversity of the species. Furthermore, it is necessary to appraise the plus trees of Swida wilsoniana by the methods of genetic diversity analysis for selecting high-production plus trees. By the research of morphology and allozyme, we drew a conclusion:1,This paper firstly combined classical morphological markers with enzyme marks to research and disscuss the heredity multiplicity and heredity rule of pluss trees of Swida wilsoniana. Meanwhile, the researched results constructed and formed the method of observating and recording of the important hereditary feature, the evaluation criteria and the quantitative heredity model of Swida wilsoniana.2,Based on the results of forward selection, first sorting and check,which had done by other researchers in 1997-2001,this paper analyzed the original data and assessed 16 superior isolates for propagation. They are DA7,DA46,XT33,JY21,QD27,XE56,LS21,YD17,YD83,SC22,LN1,LN7,LN39,HF8,XE21 and JL65.3,The paper firstly applied morphological method to analyze 25 morphological traits of the plus trees of Swida wilsoniana, and found that the genetic variation was very abundant between the plus trees. In the morphological traits, the genetic variation of effective number of branches was 81.70% and was up to the highest value among the all recorded morphological traits. Meanwhile, there were different-degree genetic variation in other morphological traits, such as tree height, height of culm, degree of density of branch, blade length, fruit transverse diameter, fruit longitudinal diameter etc. The diversity index is an important genetic index which can describe the variable scope. The average value of diversity index between the plus trees was 1.587, and it indicated there was much genetic diversity between trees that came from different areas. At the same times, the difference of vary between genetic variation coefficient and genetic diversity index told us that there was not inevitable correlation between the two diversity indexes. Different index reflected different variable degree. Based on the result of classification, we knew that the plus trees from different areas could be divided into 5 groups.The first group contains the plus trees of DA7,DA46,QD27,XT33,SC22,LN1,LN7,HF8 and JL65; The second group include the plus trees of JY21,XE56,YD17 and XE21; The last tree groups only contain one isolate, and there are the plus trees of LS21,YD83 and LN39.The euclidean distance varied from 3.84 to 9.82, while the average genetic distance was 6.53.The principal components analysis attributed 25 morphological traits to 6 principal components (or principal factors) and the cumulative construction ratio was up to 77.73%(>72%). The 6 principal components could basically include most of information which was contained by 25 morphological traits. First of all, the first principal factor was called figure factor which described characteristics of the plus trees; Secondly, the second principal factor was called stem-leaf factor which reflected characteristics of stems and leaves; Last, the other factors were called composition-factor.4,The paper firstly adopted 4 enzyme systems which included Alcohol Dehydrogenase, Aspartate Aminotransferase, Malate Dehydrogenase and Phosphoglucomutase to analyze the genetic diversity of the plus trees. Results showed there was some-degree difference, and the frequency of allele ranged from 0.094 to 0.750.The average value of number of alleles in every loci was 2.55; the average value of effective number of alleles was 2.14. The Shannon's information index, the number of polymorphic loci and the percentage of polymorphic loci accordlly were 0.757,9,81.82% and 0.470.All of these values explained the existence of genetic variation in these plus trees. The genetic identity ranged from 0.595 to 0.939, while the average value was 0.756; the genetic distance varied from 0.063 to 0.519, as the average value was 0.287. In the figure of classification, we can divided the plus trees to 5 groups at 12.3 in genetic linkage map. The first group included the plus trees of DA7,DA46,QD27,LN1 and LN7;the second group contained the plus trees of JY21,XE56,XT33,SC22,XE21 and JL65;the third group was composed of the plus trees of LS21,HF8 and YD17;the forth and fifth group only contained one plus tree (YD83 and LN39).From the result of classification, we knew the last two groups might exist much more genetic diversity through comparing to the fist three groups.The result of study based on morphology and allozyme showed that populations with a close origin and similar distributing area or similar growth environment could get a prior clustering.