| Plant invasion was the most important component of biological invasion which was one of the major global problems recently.Wedelia trilobata was a serious invasive plant in many provinces and regions in southern China.It had been shown that the W.trilobata had a strong environmental adaptability,which was one of the important reasons for its successful invasion.In this study,the genetic diversity and population genetic structure of W.trilobata from 12 regions of China were analyzed by simple sequence repeat(SSR)molecular markers.Meanwhile,the environmental adaptability of W.trilobata was analyzed based on 9 environmental factors,and the correlation between genetic diversity and environmental factors was explored.The main results were as follows:1.Based on the transcriptome sequencing data of W.trilobata,a total of 88504 unigenes were obtained.18 644 of them contained SSR loci(21.07%),and 23338 SSR loci were obtained(26.37%).The average distribution distance was 1.23 Mb.The rich of SSR loci was beneficial to developing SSR markers for W.trilobata.The monoucleotide repeats in the six nucleotide repeats were the most abundant repeat type and the most abundant motif of the dinucleotide repeats was AG/CT,and AAT/ATT motif in trinucleotide repeats was the most frequent.Based on the transcriptome data and previous research,6 SSR loci were developed for W.trilobata.The genetic diversity analysis showed that the polymorphism information content(PIC)was 0.511,indicating that the SSR loci was polymorphic and could be used for genetic diversity analysis of W.trilobata.2.Based on the 6 SSR loci,the genetic diversity of 12 W.trilobata populations was analyzed.The results showed that the average percentage of polymorphic loci(P),the number of observed allele(Na)and effective number ofalleles(Ne)were 100%,2.833 and 2.637,respectively.And the average of expected heterozygosity(He)and Shannon diversity index(I)were 0.597 and 0.973 respectively.It meant that W.trilobata populations had high genetic diversity,which might be attributed to its reproductive pattern,growth environment and multiple introductions.For W.trilobata,genetic differentiation among populations was relatively small with the genetic differentiation coefficient Gst of 0.178,and the genetic variation was mostly from the inter population.Gene flow(Nm)was 1.515,indicating frequent gene exchange among populations.The cluster analysis based on UPGMA divided 12 W.trilobata populations into 5 branches,Haikou,Nanning and Yangjiang formed a branch,respectively.Fuzhou,Guangzhou and Xishuangbanna were combined into one cluster,the rest of Zhanjiang,Shaoguan,Chaozhou,Meizhou,Wuzhou and Yulin were combined into one cluster.3.The study on the environmental adaptability of W.trilobata found that temperature was the dominant environmental factor affecting its distribution,and its main distribution area's climate was the tropical and subtropical high temperature climate.W.trilobata was highly tolerant to high temperature but sensitive to low temperature.Therefore,global warming would promote its spread to high latitude area.In addition,the results showed that there was no significant correlation between genetic diversity of W.trilobata and environmental factors.The possible reason was that these environmental factors had a synergistic effect on the genetic diversity of W.trilobata during its invasion process,and there was no direct correlation with a certain environmental factor. |
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