The Study Of Genetic Diversity Of Natural Populations Of Linaria Vulgaris(L)Mill(Plantaginaceae) In China

The genus of Linaria Mill is a useful medicinal and landscaping plants.Linariavulgaris(L) Mill is widely distributed in the north of China. And its breeding systemis obligated outcrossing named as self-incompatibility,which is assumed to promotegenetic diversity in nature population. In this study, the technology of randomamplified polymorphic DNA (RAPD) was used to analyze genetic variation of fournatural populations of L. vulgaris in china aiming to explore the relationship betweenbreeding system and genetic diversity in Linaria. In addition, we proposed to figureout the most appropriate molecular marker of four cpDNA regions of L.vulgaris, inorder to analysis genetic diversity of L.vulgaris in its whole distribution area in china.The main results are listed as follows:1)88bands were totally generated from96individuals of4populations ofL.vulgaris. The percentage of polymorpgic bands (PPB) was89.77， Nei’s genediversity (h) was0.244and shannon index(I) was0.388. The value of the threegenetics parameters suggest that all four populations of L.vulgaris possess a high levelof genetic diversity. Coefficient of gene differentiation (Gst) was0.138fromPOPGENE, showing that the majority of genetic variation existed inside populations.The result was consistent with the recently published data in Linaria and its closelyrelative Antirrhinum, where the mean value of Gst in materials with self-incompatibility system is0.03and0.130in two genus respectively, while the value is0.52and0.822in self-compatible materials. So, the RAPD data provide someevidence for our assumption that the obligated outcrossing of breeding system in L.vulgaris is the main enhancing factor of genetic diversity in the natural populations,because the artificial hybridization experiment found that the majority of individualsin the populations are self-sterile and produced no seeds in selfing cross.2)The cluster analysis of RAPD revealed that many individuals of differentpopulations usually collocated with individuals of other populations in cladistic tree,indicating that four populations had experienced some mixture events during theevolutionary history. The observation is supported by the following sequence analysisof cpDNA to some extent. In gene tree of rpl32-trnL,4individuals of Chazi andWeichang populations separated in different branches rather than clustered with the other individual in same population. Further, the value of Nm equals to3.120indicates that there was some gene flow existing in different inter-populations. Thefrequent gene flow and population mixture events deny our hypothesis that there issome relevant relationship between the geographical distance and genetic distance inL. vulgaris.3)Four cpDNA fragments, rpl32-trnL, trnQ-5’rps16, trnT-trnL, trnS-trnG in fourL. vulgaris populations were sequenced. The results of sequences alignment andphylogenetic analysis indicate that rpl32-trnL is805bp in long after aligning, whichcontains24potential parsimony information sites, and is selected to serve as the idealmolecular marker for further study of population genetics in next step.