Studies On Genetic Diffrences Of Verbena Species And Genetic Diversity Of Verbena Brasiliensis Vell

Verbena belongs to Verbenaceae, including about 250 species, chiefly in tropical America. In China, all Verbena species are exotic, including V.officinalis L., V. bonariensis L., V. brasiliensis Vell., V. hybrida Voss and V. tenera Spreng. This study analyzed the phylogeny relationship of Verbena by using ITS and cp DNA spacer sequences. And Lantana camara L. and L. montevidensis Briq. were used as outgroups here. The population genetic structures of V. brasiliensis and V. bonariensis were also revealed by using ISSR molecular markers. The main research results are as follows: 1. Phylogeny study based on ITS and cp DNA spacer sequenceITS and two cp DNA spacer sequences(trn S-trn G and psb A-trn H) were used in this study. In trn S-trn G, 132 base mutation sites and 9 haploid types were found, the haploid type polymorphism(Hd) is 0.749, the nucleotide polymorphisms(PI) is 0.01313. In psb A-trn H, a total of 72 sequence variation sites and 8 haploid types were revealed, Hd and PI were 0.598 and 0.00949, respectively. Higher variations were found in ITS, 247 base mutation sites including a 60 bp indel, 11 haploid types, Hd and PI were 0.830 and 0.04806, respectively. There are a total of 451 base mutation sites and 13 haploid types in combined sequence(ITS and cp DNA), Hd and PI were 0.830 and 0.02516, respectively. The genetic differentiation coefficient(Gst) among species is 0.86822, gene flow(Nm) is 0.04; according to the results of AMOVA, there is little differentiation among populations in species, and the higher genetic differentiation are detected among species.Both ITS and cp DNA results showed that the Verbena species divided into two main clades. V. brasiliensis and V. bonariensis are sister groups. And then formed a main clade with V. officinalis with high bootstrap value. While the other clade was composed of V. hybrida and V. tenera. 2. Genetic diversity analysis of V. brasiliensis based on ISSR molecular markersWe selected 12 ISSR primers to amplify the 230 samples. Genetic diversity analysis showed that, at the species level, V. brasiliensis diversity index(PPB=65.22%,I=0.145,He=0.077,Ne =1.095) is higher than the V. bonariensis(PPB = 50%, I = 0.278, He = 0.186, Ne = 1.165). At the group level, genetic differentiation of V. brasiliensis populations was high, Gst and Nm were 0.446 and 0.621, respectively. The population PYX had the highest polymorphism(PPB=49.28%, I=0.284, He=0.194, Ne=1.334). Among V. bonariensis populations, the genetic diversity of AXLM population was the highest(PPB=37.68%, I=0.188, He=0.124, Ne=1.205).AMOVA analysis showed that the differences between V. brasiliensis and V. bonariensis were mainly from species(76.32%), and the differences among V. brasiliensis populations mainly from sections(47.55%). Genetic differentiation cosfficient(Gst=0.446, Nm=0.621) of V. brasiliensis were higher than V. bonariensis(Gst=0.197,Nm=2.034). And V. brasiliensis populations were clearly differentiated into two sections, XT, ZTL and GDL populations were assembled in one section(Gst=0.226, Nm=0.226), and other populations got together for another section(Gst=0.305, Nm=0.305). The gene exchange between sections was less, while it was obvious among groups within sections.According to clustering analysis, all species were divided into two main clades(V. brasiliensis and V. bonariensis). Among V. brasiliensis populations, Vsp, XT, GDL and ZTL populations formed one clade, and the other populations formed another clade, which consistent with the front result based on ITS-cp DNA combined sequence analysis.Using MVSP software to analysis the data of ISSR, all 14 populations were divided into four main areas, V. bonariensis mainly hold together at the far right, V. brasiliensis were mainly distributed at the left conversely. Several samples of AXLM and PYX populations spread over the middle position, which meaned that AXLM and PYX populations had a higher genetic diversity, and in concert with the clustering analysis.Structure analysis showed that V. brasiliensis populations came from two different gene pools, and V. bonariensis populations came from a single gene pool.ISSR results showed that V. bonariensis and V. brasiliensis had low genetic differentiation in the population levels. V. bonariensis populations had low genetic differentiation and the gene exchange is frequent; on the contrary, V. brasiliensis populations had higher genetic differentiation, and divided into two groups.