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中国科学院昆明植物研究所知识管理系统
Knowledge Management System of Kunming Institute of Botany,CAS
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GST,p < 0.001) and low levels of seed-based gene flow. C. debaoensis (Cycadaceae) is an endangered species restricted to the border of Guangxi and Yunnan province in southwest China. This species has been classified into two types: sand and karst, according to the soil matrix they grow on. We examined chloroplast sequence variation of the cpDNA sequences from 11 populations of this species. Significant population genetic differentiation was detected (GST= 0.684 and FST = 0.74160). There was marked genetic differentiation between populations in the sand and karst regions and no expansion was detected. Climate changes during glacial periods have had significant effects on the current distribution of cycads. The molecular phylogenetic data, together with the geographic distribution of the haplotypes, suggest that C. debaoensis experienced range contraction during glacial periods, and that the current populations are still confined to the original refugia in southwest China which have favorable habitats in glacial period. These results imply that small refugia were maintained in both sand and karst regions during the LGM (last glacial maximum). This species had no postglacial recolonization and only stayed in these refugia up to now. The low within-population diversity of C. debaoensis suggests that there were strong bottleneck events or founder effects within each separate region during the Quaternary climatic oscillations. Relatively high genetic and haplotype diversities were detected in the newly discovered populations, which located at intermediate locality of sand regions and had morphological variation; this is probably the consequence of the admixture of different haplotypes colonizing the area from separate sources. C. micholitzii occurs in the Annan Highlands in central Vietnam near the Laos border. C. bifida occurs in North Vietnam; its distribution extends across the border into adjacent localities in Guangxi and Yunnan in China. For the comparability between them,theywere considered as the same species C. micholitzii by many academicians. The cpDNA sequences from 11 populations showed that these very controversial species, C. micholitzii and C. bifida, is paraphyletic and should belong to the same species C. micholitzii. AMOVA analysis showed that the component of among-population within region/species (76.46%) was unexpectedly larger than the among-species/region component (14.97%), which also indicates that there is no justification for recognizing two species as C. micholitzii and C. bifida. This hypothesis was also supported by the geological data, especially the neotectonic history of the indo-china block, which started to move south since Oligocene and cause the geographic isolation of these two groups. Therefore, the most likely explanation to the phenotypic similarities between these two groups may be the retention of ancestral polymorphisms in the paraphyletic group due to incomplete lineage sorting. Furthermore, the similarities may also be ascribed to pollen-mediated gene flow among geographically proximate populations and/or phenotypic convergence under similar selection schemes in the same region. C.micholitzi had the higest genetic diversity (HT = 0.980,) and genetic differentiation (GST = 0.830, NST = 0.915) among the C. micholitzii complex. The high genetic diversity might be attributed to its long evolutionary history, highly diverse habitats. The ineffective mode of seed dispersal and dramatic neotectonic movement in the distribution range of this species could result in the high genetic differentiation. 2. Phylogeographic analysis based on nuclear ribosomal sequences, We sequenced the nrDNA ITS in all 27 populations sampled, 7 haplotypes were identified, among which C. micholitzii had 6, while C. multipinnata, C. longipetiolula and C. debaoensis shared the remaining one. Compared to chloroplast genes, nuclear genes had higher correlation between genetic and geographical distance, but lower interspecies differentiation (54.42% vs 25.24%). Phylogeographical structure of C. micholitzii and C.bifida based on ITS Variation was consistent with the morphology differentiation. This similar in nuclear gene should be ascribed to pollen-mediated gene flow among geographically proximate populations.Long-distance gene flow over the two groups was clearly interrupted, which brought on the nrDNA genetic differenciation between the geographically isolated groups, to a certain extent affected the morphological variation. 3. Interspecies relationships among Cycas micholitzii complex, We analysed chloroplast sequence variation of the atpB-rbcL and psbA-trnH intergenic spacers in 27 populations sampled of C. micholitzii complex, AMOVA analysis showed that the component of among-species/region component (59.21%). However, phylogenic analysis showed that the haplotypes of C. micholitzii complex couldn`t grouped into four clusters closely corresponding to the narrowly defined C. micholitzi, C. multipinnata, C. debaoensis and C. longipetiolula. We concluded that the conflict may result from several factors: firstly incomplete lineage sorting of C. micholitzii; secondly hybridization/introgression of sympatrically cycads, which would be supported by evidence base on nrDNA ITS sequences; thirdly intramolecular recombination in cpDNA of cycads; eventually the neotectonic movement in the distribution range of this species.","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3ACycas%5C+micholitzii%5C+complex%5C+is%5C+composed%5C+of%5C+5%5C+species%5C%3A%5C+C.%5C+micholitzii%5C+Dyer%2C%5C+C.%5C+bifida%5C+%5C%28Dyer%5C%29%5C+K.%5C+D.%5C+Hill%2CC.%5C+longipetiolula%5C+D.%5C+Y.%5C+Wang%2C%5C+C.%5C+debaoensis%5C+Y.%5C+C.%5C+Zhong%5C+et%5C+C%5C+J.%5C+Chen%2C%5C+C.%5C+multipinnata%5C+C%5C+J.%5C+Chen%5C+et%5C+S.%5C+Y.%5C+Yang%EF%BC%8Cand%5C+distributed%5C+from%5C+southwest%5C+China%5C+to%5C+central%5C+Vietnam%5C+and%5C+eastern%5C+Laos.%5C+Based%5C+on%5C+sequence%5C+data%5C+from%5C+two%5C+maternally%5C+inherited%5C+cpDNA%5C+and%5C+one%5C+biparentally%5C+nuclear%5C+DNA%5C+fragments%2C%5C+our%5C+study%5C+revealed%5C+the%5C+population%5C+genetic%5C+structure%5C+of%5C+C.%5C+micholitzii%5C+complex%5C+and%5C+explored%5C+the%5C+potential%5C+causes.%5C+The%5C+evolutionary%5C+and%5C+demographic%5C+histories%5C+were%5C+investigated.%5C+The%5C+genetic%5C+relationship%5C+among%5C+species%5C+in%5C+the%5C+complex%5C+was%5C+also%5C+clarified.The%5C+results%5C+were%5C+summarized%5C+as%5C+follows%5C%3A%5C+1.%5C+Phylogeographic%5C+analysis%5C+based%5C+on%5C+chloroplast%5C+sequences%EF%BC%8CWe%5C+examined%5C+chloroplast%5C+sequence%5C+variation%5C+of%5C+the%5C+atpB%5C-rbcLand%5C+psbA%5C-trnHintergenic%5C+spacers%5C+in%5C+27%5C+populations%5C+of%5C+C.%5C+micholitzii%5C+complex%2C%5C+recovering%5C+26%5C+haplotypes.%5C+The%5C+average%5C+within%5C-population%5C+diversity%5C+%5C%28HS%5C+%3D%5C+0.140%5C%29%5C+was%5C+low%5C+while%5C+total%5C+diversity%5C+%5C%28HT%5C+%3D%5C+0.911%5C%29%5C+was%5C+high.%5C+Population%5C+differentiation%5C+was%5C+also%5C+high%5C%28GST%5C+%3D%5C+0.846%2C%5C+NST%5C+%3D%5C+0.919%5C%29%2C%5C+indicating%5C+significant%5C+phylogeographical%5C+structure%5C+%5C%28NST%5C+%3E%5C+GST%2Cp%5C+%3C%5C+0.001%5C%29%5C+and%5C+low%5C+levels%5C+of%5C+seed%5C-based%5C+gene%5C+flow.%5C+C.%5C+debaoensis%5C+%5C%28Cycadaceae%5C%29%5C+is%5C+an%5C+endangered%5C+species%5C+restricted%5C+to%5C+the%5C+border%5C+of%5C+Guangxi%5C+and%5C+Yunnan%5C+province%5C+in%5C+southwest%5C+China.%5C+This%5C+species%5C+has%5C+been%5C+classified%5C+into%5C+two%5C+types%5C%3A%5C+sand%5C+and%5C+karst%2C%5C+according%5C+to%5C+the%5C+soil%5C+matrix%5C+they%5C+grow%5C+on.%5C+We%5C+examined%5C+chloroplast%5C+sequence%5C+variation%5C+of%5C+the%5C+cpDNA%5C+sequences%5C+from%5C+11%5C+populations%5C+of%5C+this%5C+species.%5C+Significant%5C+population%5C+genetic%5C+differentiation%5C+was%5C+detected%5C+%5C%28GST%3D%5C+0.684%5C+and%5C+FST%5C+%3D%5C+0.74160%5C%29.%5C+There%5C+was%5C+marked%5C+genetic%5C+differentiation%5C+between%5C+populations%5C+in%5C+the%5C+sand%5C+and%5C+karst%5C+regions%5C+and%5C+no%5C+expansion%5C+was%5C+detected.%5C+Climate%5C+changes%5C+during%5C+glacial%5C+periods%5C+have%5C+had%5C+significant%5C+effects%5C+on%5C+the%5C+current%5C+distribution%5C+of%5C+cycads.%5C+The%5C+molecular%5C+phylogenetic%5C+data%2C%5C+together%5C+with%5C+the%5C+geographic%5C+distribution%5C+of%5C+the%5C+haplotypes%2C%5C+suggest%5C+that%5C+C.%5C+debaoensis%5C+experienced%5C+range%5C+contraction%5C+during%5C+glacial%5C+periods%2C%5C+and%5C+that%5C+the%5C+current%5C+populations%5C+are%5C+still%5C+confined%5C+to%5C+the%5C+original%5C+refugia%5C+in%5C+southwest%5C+China%5C+which%5C+have%5C+favorable%5C+habitats%5C+in%5C+glacial%5C+period.%5C+These%5C+results%5C+imply%5C+that%5C+small%5C+refugia%5C+were%5C+maintained%5C+in%5C+both%5C+sand%5C+and%5C+karst%5C+regions%5C+during%5C+the%5C+LGM%5C+%5C%28last%5C+glacial%5C+maximum%5C%29.%5C+This%5C+species%5C+had%5C+no%5C+postglacial%5C+recolonization%5C+and%5C+only%5C+stayed%5C+in%5C+these%5C+refugia%5C+up%5C+to%5C+now.%5C+The%5C+low%5C+within%5C-population%5C+diversity%5C+of%5C+C.%5C+debaoensis%5C+suggests%5C+that%5C+there%5C+were%5C+strong%5C+bottleneck%5C+events%5C+or%5C+founder%5C+effects%5C+within%5C+each%5C+separate%5C+region%5C+during%5C+the%5C+Quaternary%5C+climatic%5C+oscillations.%5C+Relatively%5C+high%5C+genetic%5C+and%5C+haplotype%5C+diversities%5C+were%5C+detected%5C+in%5C+the%5C+newly%5C+discovered%5C+populations%2C%5C+which%5C+located%5C+at%5C+intermediate%5C+locality%5C+of%5C+sand%5C+regions%5C+and%5C+had%5C+morphological%5C+variation%5C%3B%5C+this%5C+is%5C+probably%5C+the%5C+consequence%5C+of%5C+the%5C+admixture%5C+of%5C+different%5C+haplotypes%5C+colonizing%5C+the%5C+area%5C+from%5C+separate%5C+sources.%5C+%5C+C.%5C+micholitzii%5C+occurs%5C+in%5C+the%5C+Annan%5C+Highlands%5C+in%5C+central%5C+Vietnam%5C+near%5C+the%5C+Laos%5C+border.%5C+C.%5C+bifida%5C+occurs%5C+in%5C+North%5C+Vietnam%5C%3B%5C+its%5C+distribution%5C+extends%5C+across%5C+the%5C+border%5C+into%5C+adjacent%5C+localities%5C+in%5C+Guangxi%5C+and%5C+Yunnan%5C+in%5C+China.%5C+For%5C+the%5C+comparability%5C+between%5C+them%2Ctheywere%5C+considered%5C+as%5C+the%5C+same%5C+species%5C+C.%5C+micholitzii%5C+by%5C+many%5C+academicians.%5C+The%5C+cpDNA%5C+sequences%5C+from%5C+11%5C+pop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a field trip at a brule in Shangri-La, a mixed population of Ligularia Cass. was found, which including L. subspicata (Bur. et Franch.) Hand.-Mazz., L. nelumbifolia (Bur. et Franch.) Hand.-Mazz., L. tongolensis (Franch.) Hand.-Mazz., L. cymbulifera (W.W.Smith) Hand.-Mazz., L. lingiana S.W.Liu, and also some individuals morphologically intermediate between L. subspicata and L. nelumbifolia. Hence, these intermediate individuals were preliminarily assumed as natural hybrids of the two Ligularia. According to their morphology, they’re assumed to form hybrids A and B. Through careful comparison of specimens in herbarium and those we collected, the inflorescence of putative hybrid A is close to L. nelumbifolia, but the shape of laminae are intergradation of L. subspicata and L. nelumbifolia; overall morphology of putative hybrids B is similar to L. nelumbifolia, but inflorescence color is as same as L. subspicata. Compared to L. nelumbifolia (39%) and L. subspicata (36.8%), the germination rate of putative hybrid B (45.7%) slightly higher than the two; but that of hybrid A is extraordinarily low (0.3%). One possible interpretation of the low rate is hybridization. 60 individuals were collected, including putative parents, other 4 species of Ligularia nearby, putative hybrid A and B. They were all direct sequenced of four cpDNA fragments, and direct sequenced or cloning sequenced of nrDNA ITS4-5. The results support that L. nelumbifolia and L. subspicata are parents of putative hybrid A, and the majority female parent is L. subspicata, L. vellerea may also be involved in the hybridization in some degree; the nuclear sequences of putative hybrid B have no superposition, and its chloroplast DNA sequences are identical with L. nelumbifolia, so putative hybrid B could not be hybrid; and there are backcross individuals exist among the putative parent L. subspicata. NewHybrids analysis of ISSR markers indicated that, the individuals of putative hybrid A are almost L. nelumbifolia and L. subspicata F1 hybrid generation (10/11), only 1/11 possibly backcross or other forms; all individuals of hybrid B are L. nelumbifolia; except one individual of L. subspicata as backcrossed, the other parent individuals are 100% reliable. This study focused on molecular evidence, complemented by ecological, reproductive and other characteristics, we demonstrated that the morphologically intermediate individuals’ origin, and the probability of belonging to each parental or hybrid class. And concluded that L. nelumbifolia and L. subspicata are the parents of putative hybrid A, L. vellerea may also be involved in the hybridization in some degree, hybrids mainly are the first generation, a few individuals may be involved in backcross, and most probably backcross with L. subspicata according to the anthesis, while the assumption of hybrid B is not 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stresses could limit plant growth, development and propagation. Abiotic stress refers to the negative impact factors to the plants, such as extreme temperature, drought, flood, salinity, irradiation, chemicals and so on. To understand the mechanism of abiotic stress is very important.Membrane is the most sensitive organs in the cell that response to environmental changes. Cells respond and transduct environmental signals by changing content of membrane lipids and membrane proteins. The activity change of membrane phospholipase D (PLD) and the composition and content of membrane lipid molecules is one of the most anti-stress methods for the plants. It was reported that plants responded to some abiotic stresses such as freezing, thawing, seed aging and dehydration through changing lipid molecules especially the messenger phosphatidic acid (PA) and mutants of PLD were more tolerant to those stresses. It is important to investigate the characteristics and variation of membrane lipids and membrane proteins to understand the streee in plants.Three different kinds of stresses, including alpine scree temperature stress, allelopathy and Gamma irradiation stress, were studied in the present dissertation. And try to understand how plants response to those stresses by changing membrane system and the function of PLD in resistant to those stresses, lipidomic methods were used to profiling the changing of 11 lipids classes (160 lipids molecules) under thoses stresses. Moreover, PLD mutants were also used to study the role of PLD under those stresses. The mechanisms of plants response to stresses were very complicated; PLD and lipid molecules were not the only factors that response to stresses, the metabolism and phytohormones of tested plants under these stresses were also studied.In alpine scree of northwest Yunnan, the temperature was various from 33 °C during the midday to 4 °C at night, and the highest temperature could reach to 35 to 40 °C. Saussurea medusa and Solms-Laubachia linearifolia, which live in this environment, were chosen as studied model. The results showed that membrane lipid of these two plants significantly fluctuated with the temperature, while the double bond index (DBI) that had close relationship to temperature did not change. Furthermore, the the lysolipids which rise significantly under stresses did not change too much either. Laboratory mimic experiments also confermed the characteristics of lipids change to temperature in alpine scree plants. The results suggested that the plants living in such temperature changeable environment had already adapted to this situation and their membrane responded to the temperature was a kind of adaptation instead of stress response.Since the first introduction in Yunnan province of China in 1940s, E. adenophorum has spread very rapidly especially in southwestern China. Without understanding its invasive mechanism, it is impossible to control it. o-Hydroxycinnamic acid (o-HCA), an allelochmeical isolated from leachates of aerial parts of E. adenophorum were studied. o-HCA was abundant in aerial parts of E. adenophorum (1g/10kg fresh weight). The data showed that o-HCA not only had strong allelopathic effect on Arabidopsis seeds germination, but also inhibited seedling growth, and even induced root death of Arabidopsis seedlings. It could be proposed that o-HCA affected seedlings indirectly, through inducing root cell death, and it disturbed the water and ion absorption of plants and finally induced seedling to die. Interestingly, o-HCA could also inhibit E. adenophorum seed germination, while it showed no effect on its seedling growth. E. adenophorum can produce thousands of seeds and has the ability to vegetative reproduction, with which may alleviate the harmful effect of o-HCA on E. adenophorum. Unlike E. adenophorum, its neighbors’ population was inhibited, under this situation, E. adenophorum coule have better condition to live and invade successfully.Arabidopsis were irradiated with gamma rays, and 50-100 Gy gamma irradiation could inhibit seedling growth, and with the dosage above 200 Gy it could inhibit seedling flowering. Treated Arabidopsis wild types and their PLD a and d mutant with gamma ray showed no significant differences among them. The lipid molecules changes of seedlings under stress of gamma ray were also tested, and found that Gamama ray induced lipids degradation, among which, MGDG and DGDG degraded dramatically, while the average carbons in lipids did not changed. The lipids content (nmol per mg dry weight) decreased significantly, while the mol% content (mol% of total) changed slightly. Gamma irradiation also leaded to dramatically change of Arabidopsis seedling metabolomics and the phytohormones (ABA，ZR，JA，IAA).","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3AEnvironmental%5C+stresses%5C+could%5C+limit%5C+plant%5C+growth%2C%5C+development%5C+and%5C+propagation.%5C+Abiotic%5C+stress%5C+refers%5C+to%5C+the%5C+negative%5C+impact%5C+factors%5C+to%5C+the%5C+plants%2C%5C+such%5C+as%5C+extreme%5C+temperature%2C%5C+drought%2C%5C+flood%2C%5C+salinity%2C%5C+irradiation%2C%5C+chemicals%5C+and%5C+so%5C+on.%5C+To%5C+understand%5C+the%5C+mechanism%5C+of%5C+abiotic%5C+stress%5C+is%5C+very%5C+important.Membrane%5C+is%5C+the%5C+most%5C+sensitive%5C+organs%5C+in%5C+the%5C+cell%5C+that%5C+response%5C+to%5C+environmental%5C+changes.%5C+Cells%5C+respond%5C+and%5C+transduct%5C+environmental%5C+signals%5C+by%5C+changing%5C+content%5C+of%5C+membrane%5C+lipids%5C+and%5C+membrane%5C+proteins.%5C+The%5C+activity%5C+change%5C+of%5C+membrane%5C+phospholipase%5C+D%5C+%5C%28PLD%5C%29%5C+and%5C+the%5C+composition%5C+and%5C+content%5C+of%5C+membrane%5C+lipid%5C+molecules%5C+is%5C+one%5C+of%5C+the%5C+most%5C+anti%5C-stress%5C+methods%5C+for%5C+the%5C+plants.%5C+It%5C+was%5C+reported%5C+that%5C+plants%5C+responded%5C+to%5C+some%5C+abiotic%5C+stresses%5C+such%5C+as%5C+freezing%2C%5C+thawing%2C%5C+seed%5C+aging%5C+and%5C+dehydration%5C+through%5C+changing%5C+lipid%5C+molecules%5C+especially%5C+the%5C+messenger%5C+phosphatidic%5C+acid%5C+%5C%28PA%5C%29%5C+and%5C+mutants%5C+of%5C+PLD%5C+were%5C+more%5C+tolerant%5C+to%5C+those%5C+stresses.%5C+It%5C+is%5C+important%5C+to%5C+investigate%5C+the%5C+characteristics%5C+and%5C+variation%5C+of%5C+membrane%5C+lipids%5C+and%5C+membrane%5C+proteins%5C+to%5C+understand%5C+the%5C+streee%5C+in%5C+plants.Three%5C+different%5C+kinds%5C+of%5C+stresses%2C%5C+including%5C+alpine%5C+scree%5C+temperature%5C+stress%2C%5C+allelopathy%5C+and%5C+Gamma%5C+irradiation%5C+stress%2C%5C+were%5C+studied%5C+in%5C+the%5C+present%5C+dissertation.%5C+And%5C+try%5C+to%5C+understand%5C+how%5C+plants%5C+response%5C+to%5C+those%5C+stresses%5C+by%5C+changing%5C+membrane%5C+system%5C+and%5C+the%5C+function%5C+of%5C+PLD%5C+in%5C+resistant%5C+to%5C+those%5C+stresses%2C%5C+lipidomic%5C+methods%5C+were%5C+used%5C+to%5C+profiling%5C+the%5C+changing%5C+of%5C+11%5C+lipids%5C+classes%5C+%5C%28160%5C+lipids%5C+molecules%5C%29%5C+under%5C+thoses%5C+stresses.%5C+Moreover%2C%5C+PLD%5C+mutants%5C+were%5C+also%5C+used%5C+to%5C+study%5C+the%5C+role%5C+of%5C+PLD%5C+under%5C+those%5C+stresses.%5C+The%5C+mechanisms%5C+of%5C+plants%5C+response%5C+to%5C+stresses%5C+were%5C+very%5C+complicated%5C%3B%5C+PLD%5C+and%5C+lipid%5C+molecules%5C+were%5C+not%5C+the%5C+only%5C+factors%5C+that%5C+response%5C+to%5C+stresses%2C%5C+the%5C+metabolism%5C+and%5C+phytohormones%5C+of%5C+tested%5C+plants%5C+under%5C+these%5C+stresses%5C+were%5C+also%5C+studied.In%5C+alpine%5C+scree%5C+of%5C+northwest%5C+Yunnan%2C%5C+the%5C+temperature%5C+was%5C+various%5C+from%5C+33%5C+%C2%B0C%5C+during%5C+the%5C+midday%5C+to%5C+4%5C+%C2%B0C%5C+at%5C+night%2C%5C+and%5C+the%5C+highest%5C+temperature%5C+could%5C+reach%5C+to%5C+35%5C+to%5C+40%5C+%C2%B0C.%5C+Saussurea%5C+medusa%5C+and%5C+Solms%5C-Laubachia%5C+linearifolia%2C%5C+which%5C+live%5C+in%5C+this%5C+environment%2C%5C+were%5C+chosen%5C+as%5C+studied%5C+model.%5C+The%5C+results%5C+showed%5C+that%5C+membrane%5C+lipid%5C+of%5C+these%5C+two%5C+plants%5C+significantly%5C+fluctuated%5C+with%5C+the%5C+temperature%2C%5C+while%5C+the%5C+double%5C+bond%5C+index%5C+%5C%28DBI%5C%29%5C+that%5C+had%5C+close%5C+relationship%5C+to%5C+temperature%5C+did%5C+not%5C+change.%5C+Furthermore%2C%5C+the%5C+the%5C+lysolipids%5C+which%5C+rise%5C+significantly%5C+under%5C+stresses%5C+did%5C+not%5C+change%5C+too%5C+much%5C+either.%5C+Laboratory%5C+mimic%5C+experiments%5C+also%5C+confermed%5C+the%5C+characteristics%5C+of%5C+lipids%5C+change%5C+to%5C+temperature%5C+in%5C+alpine%5C+scree%5C+plants.%5C+The%5C+results%5C+suggested%5C+that%5C+the%5C+plants%5C+living%5C+in%5C+such%5C+temperature%5C+changeable%5C+environment%5C+had%5C+already%5C+adapted%5C+to%5C+this%5C+situation%5C+and%5C+their%5C+membrane%5C+responded%5C+to%5C+the%5C+temperature%5C+was%5C+a%5C+kind%5C+of%5C+adaptation%5C+instead%5C+of%5C+stress%5C+response.Since%5C+the%5C+first%5C+introduction%5C+in%5C+Yunnan%5C+province%5C+of%5C+China%5C+in%5C+1940s%2C%5C+E.%5C+adenophorum%5C+has%5C+spread%5C+very%5C+rapidly%5C+especially%5C+in%5C+southwestern%5C+China.%5C+Without%5C+understanding%5C+its%5C+invasive%5C+mechanism%2C%5C+it%5C+is%5C+impossible%5C+to%5C+control%5C+it.%5C+o%5C-Hydroxycinnamic%5C+acid%5C+%5C%28o%5C-HCA%5C%29%2C%5C+an%5C+allelochmeical%5C+isolated%5C+from%5C+leachates%5C+of%5C+aerial%5C+parts%5C+of%5C+E.%5C+adenophorum%5C+were%5C+studied.%5C+o%5C-HCA%5C+was%5C+abundant%5C+in%5C+aerial%5C+parts%5C+of%5C+E.%5C+adenophorum%5C+%5C%281g%5C%2F10kg%5C+fresh%5C+weight%5C%29.%5C+The%5C+data%5C+showed%5C+that%5C+o%5C-HCA%5C+not%5C+only%5C+had%5C+strong%5C+allelopathic%5C+effect%5C+on%5C+Arabidopsis%5C+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has natural selection determined the evolution of gene regulation by acting on major regulatory factors? This question has been attractive to many evolutionary biologists for a long time. MicroRNAs (miRNAs) are endogenous posttranscriptional repressors and play essential roles in diverse biological processes in plants. To understand how natural selection has targeted on the entire lay of miRNA regulatory modules during flower development, we resequenced 31 miRNA target sites involved in flower development from five rice populations. We found that purifying selection serves as a major evolutionary force to act on the conserved miRNA binding sites, leading to the globally reduced genetic variation in highly conserved miRNA binding sequences within the entire rice samples. Conversely, positive selection allows variations at nonconserved miRNA binding sites and acts on them in a population-specific behaviour. Further analysis revealed that the polymorphisms within target sites may serve as raw materials for diverse functions of miRNAs by means of the destabilization of duplex, abolishment of existing target sites, and creation of novel ones. Together, the above-mentioned results indicate that variations at conserved binding sites are likely deleterious during rice flower development, whereas variants at nonconserved binding sites may be conductive to flower development-related phenotypic diversities and rice population adaption to variable environmental conditions as well. To further assess functional effects and evolutionary significance of variable alleles at the target genes, we reported the detailed characterization of the haplotype and linkage disequilibrium (LD) patterns of the entire target gene (LOC_Os01g18850，SPL 1) and the 1.4 Mb flanking regions in three rice populations, namely japonica, indica and O. rufipogon. The genetic profile of SNPs at target site and its flanking regions revealed high haplotype frequency, low haplotype diversity and strong LD in two cultivatedricepopulations. By contrast, we observed the opposite phenomena in O. rufipogon. Using the long-range haplotype (LRT) test, we found strong evidence of recent positive selection for SNP 3C/T alleles at target site in the combined O. sativa. Comparsion between the two rice subpopulations indicated that the major haplotype mh 2 containing SNP 3C accounts for half of all haplotypes in indica, while mh 3 containing SNP 3T is 91% in japonica. Moreover, the extent of LD is stronger in japonica than that in inidca. These differences suggest that independent evolutionary events may have occurred in target sequences of two cultivated rice populations and stronger positive selection acted on japonica. Next, we examined geographic distribution of polymorphic variants at target sites. We found that the major alleles SNP 3T and tightly linked SNP 4A in japonica appear to be associated with the adaption to the northern climates during rice flower development.","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3AHow%5C+has%5C+natural%5C+selection%5C+determined%5C+the%5C+evolution%5C+of%5C+gene%5C+regulation%5C+by%5C+acting%5C+on%5C+major%5C+regulatory%5C+factors%5C%3F%5C+This%5C+question%5C+has%5C+been%5C+attractive%5C+to%5C+many%5C+evolutionary%5C+biologists%5C+for%5C+a%5C+long%5C+time.%5C+MicroRNAs%5C+%5C%28miRNAs%5C%29%5C+are%5C+endogenous%5C+posttranscriptional%5C+repressors%5C+and%5C+play%5C+essential%5C+roles%5C+in%5C+diverse%5C+biological%5C+processes%5C+in%5C+plants.%5C+To%5C+understand%5C+how%5C+natural%5C+selection%5C+has%5C+targeted%5C+on%5C+the%5C+entire%5C+lay%5C+of%5C+miRNA%5C+regulatory%5C+modules%5C+during%5C+flower%5C+development%2C%5C+we%5C+resequenced%5C+31%5C+miRNA%5C+target%5C+sites%5C+involved%5C+in%5C+flower%5C+development%5C+from%5C+five%5C+rice%5C+populations.%5C+We%5C+found%5C+that%5C+purifying%5C+selection%5C+serves%5C+as%5C+a%5C+major%5C+evolutionary%5C+force%5C+to%5C+act%5C+on%5C+the%5C+conserved%5C+miRNA%5C+binding%5C+sites%2C%5C+leading%5C+to%5C+the%5C+globally%5C+reduced%5C+genetic%5C+variation%5C+in%5C+highly%5C+conserved%5C+miRNA%5C+binding%5C+sequences%5C+within%5C+the%5C+entire%5C+rice%5C+samples.%5C+Conversely%2C%5C+positive%5C+selection%5C+allows%5C+variations%5C+at%5C+nonconserved%5C+miRNA%5C+binding%5C+sites%5C+and%5C+acts%5C+on%5C+them%5C+in%5C+a%5C+population%5C-specific%5C+behaviour.%5C+Further%5C+analysis%5C+revealed%5C+that%5C+the%5C+polymorphisms%5C+within%5C+target%5C+sites%5C+may%5C+serve%5C+as%5C+raw%5C+materials%5C+for%5C+diverse%5C+functions%5C+of%5C+miRNAs%5C+by%5C+means%5C+of%5C+the%5C+destabilization%5C+of%5C+duplex%2C%5C+abolishment%5C+of%5C+existing%5C+target%5C+sites%2C%5C+and%5C+creation%5C+of%5C+novel%5C+ones.%5C+Together%2C%5C+the%5C+above%5C-mentioned%5C+results%5C+indicate%5C+that%5C+variations%5C+at%5C+conserved%5C+binding%5C+sites%5C+are%5C+likely%5C+deleterious%5C+during%5C+rice%5C+flower%5C+development%2C%5C+whereas%5C+variants%5C+at%5C+nonconserved%5C+binding%5C+sites%5C+may%5C+be%5C+conductive%5C+to%5C+flower%5C+development%5C-related%5C+phenotypic%5C+diversities%5C+and%5C+rice%5C+population%5C+adaption%5C+to%5C+variable%5C+environmental%5C+conditions%5C+as%5C+well.%5C+To%5C+further%5C+assess%5C+functional%5C+effects%5C+and%5C+evolutionary%5C+significance%5C+of%5C+variable%5C+alleles%5C+at%5C+the%5C+target%5C+genes%2C%5C+we%5C+reported%5C+the%5C+detailed%5C+characterization%5C+of%5C+the%5C+haplotype%5C+and%5C+linkage%5C+disequilibrium%5C+%5C%28LD%5C%29%5C+patterns%5C+of%5C+the%5C+entire%5C+target%5C+gene%5C+%5C%28LOC_Os01g18850%EF%BC%8CSPL%5C+1%5C%29%5C+and%5C+the%5C+1.4%5C+Mb%5C+flanking%5C+regions%5C+in%5C+three%5C+rice%5C+populations%2C%5C+namely%5C+japonica%2C%5C+indica%5C+and%5C+O.%5C+rufipogon.%5C+The%5C+genetic%5C+profile%5C+of%5C+SNPs%5C+at%5C+target%5C+site%5C+and%5C+its%5C+flanking%5C+regions%5C+revealed%5C+high%5C+haplotype%5C+frequency%2C%5C+low%5C+haplotype%5C+diversity%5C+and%5C+strong%5C+LD%5C+in%5C+two%5C+cultivatedricepopulations.%5C+By%5C+contrast%2C%5C+we%5C+observed%5C+the%5C+opposite%5C+phenomena%5C+in%5C+O.%5C+rufipogon.%5C+Using%5C+the%5C+long%5C-range%5C+haplotype%5C+%5C%28LRT%5C%29%5C+test%2C%5C+we%5C+found%5C+strong%5C+evidence%5C+of%5C+recent%5C+positive%5C+selection%5C+for%5C+SNP%5C+3C%5C%2FT%5C+alleles%5C+at%5C+target%5C+site%5C+in%5C+the%5C+combined%5C+O.%5C+sativa.%5C+Comparsion%5C+between%5C+the%5C+two%5C+rice%5C+subpopulations%5C+indicated%5C+that%5C+the%5C+major%5C+haplotype%5C+mh%5C+2%5C+containing%5C+SNP%5C+3C%5C+accounts%5C+for%5C+half%5C+of%5C+all%5C+haplotypes%5C+in%5C+indica%2C%5C+while%5C+mh%5C+3%5C+containing%5C+SNP%5C+3T%5C+is%5C+91%25%5C+in%5C+japonica.%5C+Moreover%2C%5C+the%5C+extent%5C+of%5C+LD%5C+is%5C+stronger%5C+in%5C+japonica%5C+than%5C+that%5C+in%5C+inidca.%5C+These%5C+differences%5C+suggest%5C+that%5C+independent%5C+evolutionary%5C+events%5C+may%5C+have%5C+occurred%5C+in%5C+target%5C+sequences%5C+of%5C+two%5C+cultivated%5C+rice%5C+populations%5C+and%5C+stronger%5C+positive%5C+selection%5C+acted%5C+on%5C+japonica.%5C+Next%2C%5C+we%5C+examined%5C+geographic%5C+distribution%5C+of%5C+polymorphic%5C+variants%5C+at%5C+target%5C+sites.%5C+We%5C+found%5C+that%5C+the%5C+major%5C+alleles%5C+SNP%5C+3T%5C+and%5C+tightly%5C+linked%5C+SNP%5C+4A%5C+in%5C+japonica%5C+appear%5C+to%5C+be%5C+associated%5C+with%5C+the%5C+adaption%5C+to%5C+the%5C+northern%5C+climates%5C+during%5C+rice%5C+flower%5C+development."},{"jsname":"Interdisciplinary Research Project of Kunming Institute of Botany[KIB2017003]","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3AInterdisciplinary%5C+Research%5C+Project%5C+of%5C+Kunming%5C+Institute%5C+of%5C+Botany%5C%5BKIB2017003%5C%5D"},{"jsname":"Japan Society for the Promotion of Science[1264402271]","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3AJapan%5C+Society%5C+for%5C+the%5C+Promotion%5C+of%5C+Science%5C%5B1264402271%5C%5D"},{"jsname":"Joint Fund of National Natural Science Foundation of China-Yunnan Province[U1502261]","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.type_filter&advanced=false&query1=Population%2BGenomics&&fq=dc.project.title_filter%3AJoint%5C+Fund%5C+of%5C+National%5C+Natural%5C+Science%5C+Foundation%5C+of%5C+China%5C-Yunnan%5C+Province%5C%5BU1502261%5C%5D"},{"jsname":"lastIndexed","jscount":"2024-04-15"}],"资助项目","dc.project.title_filter")'>
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1
