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资助项目
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 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officinale is a valuable medicinal plants，mainly distributed in Yunnan, Guangxi and Anhui. It is necessary to understand the environmental adaptation for the effective acclimation and cultivation of this species. Up till now, there is little information on the ecophysiological adaptation of D. officinale, especially on the photosynthetic response to temperature. This paper investigated the response of photosynthesis and growth of D. officinale to temperature, and the stem polysaccharide content of D. officinale at different temperatures, in order to understand how growth temperature affect the growth and development of D. officinale and to determine the suitable temperature ranges and day-night temperature differences for the growth and development of D. officinale. The result are summarized as follows: 1. Temperature has a significant effect on the photosynthetic rate (Pn) of D. officinale, The light saturated photosynthesis at ambient CO2 concentration (Pmax) of the plants were highest at T-30/20. High photosynthetic rate at T-30/20 were related to a larger leaf area (LA) and the more balance between the maximum rate of electron transport and maximum rate of RuBP-mediated carboxylation. 2. Temperature also has a significant effect on the growth and polysaccharide content of D. officinale’s stem. The polysaccharide content of D. officinale at T-20/10 was significantly higher than at the other temperatures, but the stem length, stem node number, stem fresh weight and stem dry weight was the highest at T-30/20. 3. The utilization of solar energy were highest at T-30/15 temperature difference between day and night, it also has the highest content of chlorophyll, and respiration rate was lower, resulting in higher dry matter accumulation and accumulation of relatively higher polysaccharide content. 4. The polysaccharide content of D. officinale T-30/20 temperature difference between day and night was significantly higher than at the other temperatures, but the leaf area was smaller and chlorophyll content, stem length, node number, the average stem length, stem fresh weight and stem dry weight and other indicators are relatively low. 5. My thesis illuminated how temperature affect the growth and development of D. officinale. The suitable temperature ranges and day-night temperature differences for the growth of D. officinale are recommended as below: day temperature is 25℃ ~ 30 ℃, night temperature is 15℃ ~ 20℃, and day-night temperature difference should be maintained at 10℃ ~ 15℃.","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.date.issued.year&advanced=false&query1=Alpine%2Bspecies&&fq=dc.project.title_filter%3ADendrobium%5C+officinale%5C+is%5C+a%5C+valuable%5C+medicinal%5C+plants%EF%BC%8Cmainly%5C+distributed%5C+in%5C+Yunnan%2C%5C+Guangxi%5C+and%5C+Anhui.%5C+It%5C+is%5C+necessary%5C+to%5C+understand%5C+the%5C+environmental%5C+adaptation%5C+for%5C+the%5C+effective%5C+acclimation%5C+and%5C+cultivation%5C+of%5C+this%5C+species.%5C+Up%5C+till%5C+now%2C%5C+there%5C+is%5C+little%5C+information%5C+on%5C+the%5C+ecophysiological%5C+adaptation%5C+of%5C+D.%5C+officinale%2C%5C+especially%5C+on%5C+the%5C+photosynthetic%5C+response%5C+to%5C+temperature.%5C+This%5C+paper%5C+investigated%5C+the%5C+response%5C+of%5C+photosynthesis%5C+and%5C+growth%5C+of%5C+D.%5C+officinale%5C+to%5C+temperature%2C%5C+and%5C+the%5C+stem%5C+polysaccharide%5C+content%5C+of%5C+D.%5C+officinale%5C+at%5C+different%5C+temperatures%2C%5C+in%5C+order%5C+to%5C+understand%5C+how%5C+growth%5C+temperature%5C+affect%5C+the%5C+growth%5C+and%5C+development%5C+of%5C+D.%5C+officinale%5C+and%5C+to%5C+determine%5C+the%5C+suitable%5C+temperature%5C+ranges%5C+and%5C+day%5C-night%5C+temperature%5C+differences%5C+for%5C+the%5C+growth%5C+and%5C+development%5C+of%5C+D.%5C+officinale.%5C+The%5C+result%5C+are%5C+summarized%5C+as%5C+follows%5C%3A%5C+1.%5C+Temperature%5C+has%5C+a%5C+significant%5C+effect%5C+on%5C+the%5C+photosynthetic%5C+rate%5C+%5C%28Pn%5C%29%5C+of%5C+D.%5C+officinale%2C%5C+The%5C+light%5C+saturated%5C+photosynthesis%5C+at%5C+ambient%5C+CO2%5C+concentration%5C+%5C%28Pmax%5C%29%5C+of%5C+the%5C+plants%5C+were%5C+highest%5C+at%5C+T%5C-30%5C%2F20.%5C+High%5C+photosynthetic%5C+rate%5C+at%5C+T%5C-30%5C%2F20%5C+were%5C+related%5C+to%5C+a%5C+larger%5C+leaf%5C+area%5C+%5C%28LA%5C%29%5C+and%5C+the%5C+more%5C+balance%5C+between%5C+the%5C+maximum%5C+rate%5C+of%5C+electron%5C+transport%5C+and%C2%A0maximum%5C+rate%5C+of%5C+RuBP%5C-mediated%5C+carboxylation.%5C+2.%5C+Temperature%5C+also%5C+has%5C+a%5C+significant%5C+effect%5C+on%5C+the%5C+growth%5C+and%5C+polysaccharide%5C+content%5C+of%5C+D.%5C+officinale%E2%80%99s%5C+stem.%5C+The%5C+polysaccharide%5C+content%5C+of%5C+D.%5C+officinale%5C+at%5C+T%5C-20%5C%2F10%5C+was%5C+significantly%5C+higher%5C+than%5C+at%5C+the%5C+other%5C+temperatures%2C%5C+but%5C+the%5C+stem%5C+length%2C%5C+stem%5C+node%5C+number%2C%5C+stem%5C+fresh%5C+weight%5C+and%5C+stem%5C+dry%5C+weight%5C+was%5C+the%5C+highest%5C+at%5C+T%5C-30%5C%2F20.%5C+3.%5C+The%5C+utilization%5C+of%5C+solar%5C+energy%5C+were%5C+highest%5C+at%5C+T%5C-30%5C%2F15%5C+temperature%5C+difference%5C+between%5C+day%5C+and%5C+night%2C%5C+it%5C+also%5C+has%5C+the%5C+highest%5C+content%5C+of%5C+chlorophyll%2C%5C+and%5C+respiration%5C+rate%5C+was%5C+lower%2C%5C+resulting%5C+in%5C+higher%5C+dry%5C+matter%5C+accumulation%5C+and%5C+accumulation%5C+of%5C+relatively%5C+higher%5C+polysaccharide%5C+content.%5C+4.%5C+The%5C+polysaccharide%5C+content%5C+of%5C+D.%5C+officinale%5C+T%5C-30%5C%2F20%5C+temperature%5C+difference%5C+between%5C+day%5C+and%5C+night%5C+was%5C+significantly%5C+higher%5C+than%5C+at%5C+the%5C+other%5C+temperatures%2C%5C+but%5C+the%5C+leaf%5C+area%5C+was%5C+smaller%5C+and%5C+chlorophyll%5C+content%2C%5C+stem%5C+length%2C%5C+node%5C+number%2C%5C+the%5C+average%5C+stem%5C+length%2C%5C+stem%5C+fresh%5C+weight%5C+and%5C+stem%5C+dry%5C+weight%5C+and%5C+other%5C+indicators%5C+are%5C+relatively%5C+low.%5C+5.%5C+My%5C+thesis%5C+illuminated%5C+how%5C+temperature%5C+affect%5C+the%5C+growth%5C+and%5C+development%5C+of%5C+D.%5C+officinale.%5C+The%5C+suitable%5C+temperature%5C+ranges%5C+and%5C+day%5C-night%5C+temperature%5C+differences%5C+for%5C+the%5C+growth%5C+of%5C+D.%5C+officinale%5C+are%5C+recommended%5C+as%5C+below%5C%3A%5C+day%5C+temperature%5C+is%5C+25%E2%84%83%5C+%5C%7E%5C+30%5C+%E2%84%83%2C%5C+night%5C+temperature%5C+is%5C+15%E2%84%83%5C+%5C%7E%5C+20%E2%84%83%2C%5C+and%5C+day%5C-night%5C+temperature%5C+difference%5C+should%5C+be%5C+maintained%5C+at%5C+10%E2%84%83%5C+%5C%7E%5C+15%E2%84%83."},{"jsname":"During 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 supported.","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.date.issued.year&advanced=false&query1=Alpine%2Bspecies&&fq=dc.project.title_filter%3ADuring%5C+a%5C+field%5C+trip%5C+at%5C+a%5C+brule%5C+in%5C+Shangri%5C-La%2C%5C+a%5C+mixed%5C+population%5C+of%5C+Ligularia%5C+Cass.%5C+was%5C+found%2C%5C+which%5C+including%5C+L.%5C+subspicata%5C+%5C%28Bur.%5C+et%5C+Franch.%5C%29%5C+Hand.%5C-Mazz.%2C%5C+L.%5C+nelumbifolia%5C+%5C%28Bur.%5C+et%5C+Franch.%5C%29%5C+Hand.%5C-Mazz.%2C%5C+L.%5C+tongolensis%5C+%5C%28Franch.%5C%29%5C+Hand.%5C-Mazz.%2C%5C+L.%5C+cymbulifera%5C+%5C%28W.W.Smith%5C%29%5C+Hand.%5C-Mazz.%2C%5C+L.%5C+lingiana%5C+S.W.Liu%2C%5C+and%5C+also%5C+some%5C+individuals%5C+morphologically%5C+intermediate%5C+between%5C+L.%5C+subspicata%5C+and%5C+L.%5C+nelumbifolia.%5C+Hence%2C%5C+these%5C+intermediate%5C+individuals%5C+were%5C+preliminarily%5C+assumed%5C+as%5C+natural%5C+hybrids%5C+of%5C+the%5C+two%5C+Ligularia.%5C+According%5C+to%5C+their%5C+morphology%2C%5C+they%E2%80%99re%5C+assumed%5C+to%5C+form%5C+hybrids%5C+A%5C+and%5C+B.%5C+Through%5C+careful%5C+comparison%5C+of%5C+specimens%5C+in%5C+herbarium%5C+and%5C+those%5C+we%5C+collected%2C%5C+the%5C+inflorescence%5C+of%5C+putative%5C+hybrid%5C+A%5C+is%5C+close%5C+to%5C+L.%5C+nelumbifolia%2C%5C+but%5C+the%5C+shape%5C+of%5C+laminae%5C+are%5C+intergradation%C2%A0of%5C+L.%5C+subspicata%5C+and%5C+L.%5C+nelumbifolia%5C%3B%5C+overall%5C+morphology%5C+of%5C+putative%5C+hybrids%5C+B%5C+is%5C+similar%5C+to%5C+L.%5C+nelumbifolia%2C%5C+but%5C+inflorescence%5C+color%5C+is%5C+as%5C+same%5C+as%5C+L.%5C+subspicata.%5C+Compared%5C+to%5C+L.%5C+nelumbifolia%5C+%5C%2839%25%5C%29%5C+and%5C+L.%5C+subspicata%5C+%5C%2836.8%25%5C%29%2C%5C+the%5C+germination%5C+rate%5C+of%5C+putative%5C+hybrid%5C+B%5C+%5C%2845.7%25%5C%29%5C+slightly%5C+higher%5C+than%5C+the%5C+two%5C%3B%5C+but%5C+that%5C+of%5C+hybrid%5C+A%5C+is%5C+extraordinarily%5C+low%5C+%5C%280.3%25%5C%29.%5C+One%5C+possible%5C+interpretation%5C+of%5C+the%5C+low%5C+rate%5C+is%5C+hybridization.%5C+60%5C+individuals%5C+were%5C+collected%2C%5C+including%5C+putative%5C+parents%2C%5C+other%5C+4%5C+species%5C+of%5C+Ligularia%5C+nearby%2C%5C+putative%5C+hybrid%5C+A%5C+and%5C+B.%5C+They%5C+were%5C+all%5C+direct%5C+sequenced%5C+of%5C+four%5C+cpDNA%5C+fragments%2C%5C+and%5C+direct%5C+sequenced%5C+or%5C+cloning%5C+sequenced%5C+of%5C+nrDNA%5C+ITS4%5C-5.%5C+The%5C+results%5C+support%5C+that%5C+L.%5C+nelumbifolia%5C+and%5C+L.%5C+subspicata%5C+are%5C+parents%5C+of%5C+putative%5C+hybrid%5C+A%2C%5C+and%5C+the%5C+majority%5C+female%5C+parent%5C+is%5C+L.%5C+subspicata%2C%5C+L.%5C+vellerea%5C+may%5C+also%5C+be%5C+involved%5C+in%5C+the%5C+hybridization%5C+in%5C+some%5C+degree%5C%3B%5C+the%5C+nuclear%5C+sequences%5C+of%5C+putative%5C+hybrid%5C+B%5C+have%5C+no%5C+superposition%2C%5C+and%5C+its%5C+chloroplast%5C+DNA%5C+sequences%5C+are%5C+identical%5C+with%5C+L.%5C+nelumbifolia%2C%5C+so%5C+putative%5C+hybrid%5C+B%5C+could%5C+not%5C+be%5C+hybrid%5C%3B%5C+and%5C+there%5C+are%5C+backcross%5C+individuals%5C+exist%5C+among%5C+the%5C+putative%5C+parent%5C+L.%5C+subspicata.%5C+NewHybrids%5C+analysis%5C+of%5C+ISSR%5C+markers%5C+indicated%5C+that%2C%5C+the%5C+individuals%5C+of%5C+putative%5C+hybrid%5C+A%5C+are%5C+almost%5C+L.%5C+nelumbifolia%5C+and%5C+L.%5C+subspicata%5C+F1%5C+hybrid%5C+generation%5C+%5C%2810%5C%2F11%5C%29%2C%5C+only%5C+1%5C%2F11%5C+possibly%5C+backcross%5C+or%5C+other%5C+forms%5C%3B%5C+all%5C+individuals%5C+of%5C+hybrid%5C+B%5C+are%5C+L.%5C+nelumbifolia%5C%3B%5C+except%5C+one%5C+individual%5C+of%5C+L.%5C+subspicata%5C+as%5C+backcrossed%2C%5C+the%5C+other%5C+parent%5C+individuals%5C+are%5C+100%25%5C+reliable.%5C+This%5C+study%5C+focused%5C+on%5C+molecular%5C+evidence%2C%5C+complemented%5C+by%5C+ecological%2C%5C+reproductive%5C+and%5C+other%5C+characteristics%2C%5C+we%5C+demonstrated%5C+that%5C+the%5C+morphologically%5C+intermediate%5C+individuals%E2%80%99%5C+origin%2C%5C+and%5C+the%5C+probability%5C+of%5C+belonging%5C+to%5C+each%5C+parental%5C+or%5C+hybrid%5C+class.%5C+And%5C+concluded%5C+that%5C+L.%5C+nelumbifolia%5C+and%5C+L.%5C+subspicata%5C+are%5C+the%5C+parents%5C+of%5C+putative%5C+hybrid%5C+A%2C%5C+L.%5C+vellerea%5C+may%5C+also%5C+be%5C+involved%5C+in%5C+the%5C+hybridization%5C+in%5C+some%5C+degree%2C%5C+hybrids%5C+mainly%5C+are%5C+the%5C+first%5C+generation%2C%5C+a%5C+few%5C+individuals%5C+may%5C+be%5C+involved%5C+in%5C+backcross%2C%5C+and%5C+most%5C+probably%5C+backcross%5C+with%5C+L.%5C+subspicata%5C+according%5C+to%5C+the%5C+anthesis%2C%5C+while%5C+the%5C+assumption%5C+of%5C+hybrid%5C+B%5C+is%5C+not%5C+supported."},{"jsname":"lastIndexed","jscount":"2024-05-10"}],"资助项目","dc.project.title_filter")'>
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