| Artemisia halodendron Turcz.et Bess.is a semi-shrub of genus Artemisia in Compositae.It is mainly distributed in Horqin Sandy Land and Hulunbuir Sandy land in the northeast of China.It is an important building plant of semi-shrub communities in these two sandy lands and an important wind-breaking and sand-fixation plant.As an important buffer species in the process of vegetation degradation in sandy land,it plays an important role in stabilizing the environment of sandy land and the establishment of plant community,and has ecological and biological research and utilization value.Based on the three single-copy nuclear genes(c5830,c7847,c9002)developed in the transcriptome,this study conducted a phylogenetic study on the A.halodendron population,analyzed its genetic diversity,genetic structure and population historical dynamics,and explored the the relationship between A.halodendron and its relatives,the main research results are as follows:(1)The length of c5830 sequence was 425 bp,and there were 21 mutants,47 haplotypes in total.The length of c7847 was 475 bp,and there were 14 mutation,38 haplotypes in total.The length of c9002 sequence was 378 bp,and there were 19 mutation and 47 haplotypes in total.The total haplotype diversity of the three genes was 0.936,0.947,and 0.916,respectively,and the haplotype diversity at the population level was greater than 0.5.The total nucleotide diversity was 0.01862,0.00609,0.01384,and the population level was all If it is greater than 0.005,it comprehensively shows that A.halodendron shows high genetic diversity whether it is a species or a population.(2)The AMOVA results of c5830,c7847,and c9002 showed that the genetic variation within the populations of A.halodendron was99.91%,97.44%,and 97.63%,respectively,reflecting that the genetic variation of A.halodendron mainly existed within the population,and there was little differentiation among the populations.The gene flow were 10.07,5.32,and 5.52,which were all far greater than 1,indicating that the gene exchange among the populations of A.halodendron was very extensive.(3)The genetic differentiation coefficient of c5830 was NstGst,but the difference was not significant(P>0.05),that is,there was no obvious phylogenetic structure in the population of A.halodendron.According to the haplotype network diagram,each haplotype was interwoven and distributed in the population with obvious network structure,which had no obvious relationship with the geographical distribution of A.halodendron population.(4)The neutral test showed that the Tajima's D values of the three nuclear genes were not significant,nor were they significant at the population level,indicating that A.halodendron conformed to the neutral evolution hypothesis.The overall Fu's Fs values of c7847 and c9002 were significant,and the mismatch curve of c7847 and c9002 showed a single peak,but the total Fu's Fs value of c5830 was not significant,and the mismatch curve of c5830 showed double peaks.combined with bifurcation distribution analysis,the values of Fu's Fs,SSD and r of DQ and HLR populations were extremely significant,indicating that there was obvious population expansion,and most indexes of NM population also showed the existence of population expansion.The comprehensive results show that the A.halodendron population has experienced limited expansion in the neutral model.(5)Based on the single-copy nuclear genes c5830 and c7847,the haplotype network diagrams of A.halodendron,A.intramongolica and A.ordosica showed that the three plants shared more ancestral polymorphic haplotypes,indicating that the three plants are closely related.The statistics of population expansion of three species of plants with two nuclear genes showed that A.intramongolica had obvious population expansion in BYXL population and XWQ population in Xilinhot in the northeast,and most of the population indicators of XSQ in the northwest also showed that there was a certain population expansion.There is obvious population expansion in NM population of A.halodendron in Horqin Sandy Land.Most population indexes of DQ and HLR in Hulunbuir Sandy Land,and WD and TL in Horqin Sandy Land show that there is population expansion.There is obvious population expansion in WSQ,ETKQ and DLTQ in A.ordosica,and most indexes of other populations also show that there is a certain population expansion. |
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