Study On Genetic Diversity Of Apocynum Venetum In Inner Mongolia

As an perennial plant, Apocynum venetum Linn. is well known for its high resistance to salinity, drought, heat and leanness as well as being wildly used as medicine, fiber, ornamental plant, forage and nectariferous plant. Currently, Apocynum venetum Linn. resources in north China have been decreasing sharply owing to the environmental deterioration and abuse of human being, therefore, how to preserve and reasonably utilize Apocynum venetum Linn. resources turns into an important research topic. In this dissertation, the genetic diversity of wild Apocynum venetum Linn. in Inner Mongolia was analyzed based on morphological characteristics, AFLP, ISSR, chromosome number and POD isoenzyme phenotype to confirm the diversity of Apocynum venetum Linn. germplasm and their genetic relationship in this region, and thereby to set up the background for reasonable exploitation and utilization of Apocynum venetum Linn.. The results showed that:1. The total diversity index, diversity index within population, diversity index among populations, genetic diversity within and among populations were 1.858, 0.862, 0.996, 46.39% and 53.61%, respectively, which derived from 16 phenotypic values including plant height, stem thickness, internode length, branch length, inflorescence length, pod length, seed length, leaf length and leaf width of Apocynum venetum Linn.populations originated from Tongliao, Baotou and Bayannaoer. There were big differences among the diversity index of morphological parameters in Apocynum venetum Linn.. The higher diversity index was observed in plant height, stem thickness, node number, internode length, branch length, thousand-seed weight, seed width, pod length, top inflorescence length, calyx length, stipule length, leaf length and leaf width, indicating that these were the major characteristics giving rise to the morphological variance and were readily affected by the environment.2. The clustering of populations of Apocynum venetum Linn. originating from 3 regions of Inner Mongolia based on morphological properties showed that populations of Apocynum venetum Linn. from Tongliao was classified into one group while Apocynum venetum Linn. from Baotou and Bayannaoer belonged to another group, indicating that there was close relationship between Apocynum venetum Linn. populations from Baotou and Bayannaoer.3. 5359 AFLP loci were found by DNA amplification with 45 Apocynum venetum Linn. populations from 3 regions, with 91.22% polymorphic loci. AFLP genetic diversity index, AFLP genetic diversity index within population, AFLP genetic diversity index among populations, differentiation coefficient within population and differentiation coefficient among populations were 1.286, 0.533, 0.753, 41.45% and 58.55%, respectively. The variance of Apocynum venetum Linn. germplasm was mainly derived from variance within population and among populations. Coefficient of difference in Apocynum venetum Linn. from 3 regions varied between 0.0042 and 0.819. Regarding coefficient of difference as a benchmark, most of Apocynum venetum Linn. populations from Tongliao region were sorted into one group while most of Apocynum venetum Linn. populations from Baotou and Bayannaoer were categorized to another group, showing that the relationship between Tongliao group and Baotou group was wide.4. 65 ISSR loci, 55 polymorphic loci were observed by amplification using 6 ISSR primers. 84.62% were polymorphic loci. ISSR genetic diversity index, ISSR genetic diversity index within population, ISSR genetic diversity index among population and genetic differentiation coefficient were 0.424, 0.197, 0.227 and 53.54%, respectively. Regarding coefficient of difference as a benchmark, Apocynum venetum Linn. populations from Tongliao was classified into one group, while Apocynum venetum Linn. populations from Baotou and Bayannaoer came to another group, indicating there was close relationship between Apocynum venetum Linn. populations from Baotou and Bayannaoer.5. 20 (2n =2x =20) chromosomes were observed in Apocynum venetum Linn. from Tongliao while 16(2n =2x =16) chromosomes in Apocynum venetum Linn. from Baotou and Bayannaoer. This result demonstrated that there was difference in chromosome number among Apocynum venetum Linn. populations from west to east of Inner Mongolia.6. POD isoenzyme phenotypic zymograms at different organs (leaf, stem and root) showed some differences among Apocynum venetum Linn. populations originated from 3 different regions.