| Scutellaria tsinyunensis C. Y. Wu et S. Chow belonges to Labiatae, Scutellarioideae Briq., genus Scutellaria Linn., which is the perennial herbs and the endemic species of Jinyun Mountain.The remaining 9 small populations were fragmented as "island" distribution,habitat single, population size and the number of individuals dropped markedly, the survival situation is extremely worrying.It has showed that S. sinyunensis should be critically endangered(CR)according to the latest assessment, so that it is imminent that we take measures to protect it.It has been included in small populations of species of Chongqing city to protect by the State Forestry Administration, even been included in the first batch of Chongqing key-protected wild plants in 2015 by Chongqing People’s Government.This study was based on ITS sequence and cpDNA(psbA-trnH, trnL-F)sequences to study the genetic diversity 、genetic structure of S. tsinyunensis,to explore the system status of S. tsinyunensis in Scutellaria, to detect that whether there is gene flow occurred between S. tsinyunensis and the Scutellaria or not,Fuhermor, we attempt to reveal that the endangered mechanism of S. tsinyunensis in molecular perspective from researching the genetic diversity and genetic structure,which is the priority population to protect, then put forward a more scientific and comprehensive protection strategy.The main contents and results are as follows:1 S. tsinyunensis contained 9 haplotypes based on ITS sequence, and haplotype network diagram showed radial shape and haplotype. Hap1 was located in the center, as the original haplotype, which indicated that S. tsinyunensis was formed by a small number of individuals or population expansion, and retained the primitive haplotypes in the process of expansion.2 Genetic diversity of S. tsinyunensis(Pi=0.00275) among populations were greater than the genetic diversity within populations. And the genetic diversity was 0 that was find in small populations. The clonal propagation mode, ecological status, founder effect and bottleneck effect of S. tsinyunensis may was the effect of this phenomenon.By the neutral test, the results showed that populations of S. tsinyunensis Tajima’s D value was-0.30113, Fu’s Fs value was-1.325, were negative, and were not significantly different at p < 0.10 level, which incidacated that S. tsinyunensis was adhered to neutral evolution model and had the expansional experience phenomenon in the history.3 Analysis of molecular variance(AMOVA) showed that genetic variation existed 59.78% among the populations, 40.22% within the populations, Fst=0.59777, which incidated that there was more larger genetic differentiation among the populations of S. tsinyunensis and the inter population variation was the main source of variation. Total gene flow among populations of S. tsinyunensis Nm=0.43, Nm<1, which means that the S. tsinyunensis could not fredom to gene flow with each other,what is more, which could not enough to resist the genetic drift, resulting in genetic differentiation among populations increased.4 UPGMA clustering results showed that the individuals of different S. tsinyunensis populations were intertwined with each other, and there was no obvious geographical distribution tendency. DNAsp software analysis results show that p > 0.001, Nst>Gst, which means that there was non pedigree structure among the populations.5 NJ、ML phylogenetic tree was build based on r DNA ITS sequences indicated that S.tsinyunensis have nine kinds of haplotypes and the Scutellaria of S. yunnanensis Lévl. var. salicifolia Sun ex C H Hu、S.franchetiana Lévl、S. indica L.、S. yunnanensis Lévl.), were clustered together on a single system branch, in higher support rate of 99% which indicated that they had the closer genetic relationship.what is more, the smallest genetic distance between S. tsinyunensis and、S. franchetiana Levl. through genetic distance display. The rRNA secondary structure energy of S. tsinyunensis was in the intervening position, the rRNA secondary structure was relatively stable in the tested species.6 The populations of S. tsinyunensis had no diversity, 7 species of Scutellaria contain six haplotypes which was based on the combined on cpDNA psbA-trnH、TrnL-F sequence. S. franchetiana was Hap1, S. indica and S.yunnanensis were Hap2, which was the intinal haplotype. S. yunnanensis Levl. var. salicifolia was Hap3, S. tsinyunensis was Hap4.There were only one insertion or deletion point position、substitution of 3 base sites among the four haplotypes,the rest of the 38 variable sites were located between Hap6 and Hap5,which showed that S. tsinyunensis had more closer genetic relationship or maybe gene flow with the related species.7 The diversity of Pi=0.01462 from combined sequences, which showed that the higher genetic diversity of Scutellaria.The combined sequences Tajima’s D=0.57322 by Tajima’s D test, was not significant at p > 0.10 level, which indicated that it was a neutral evolution model. |
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