Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral(Na Cl and Na2SO4) and two alkali(Na HCO3 and Na2CO3) salts were selected to investigate their effects on germination a...Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral(Na Cl and Na2SO4) and two alkali(Na HCO3 and Na2CO3) salts were selected to investigate their effects on germination and recovery responses in Reaumuria soongorica. Results show that both salt types significantly reduced germination and radicle elongation. The rate of germination and emergence of R. soongorica seeds continuously decreased as salinity increased, and the time to achieve maximum germination rate was delayed. The speed of seed germination dropped rapidly as salt concentration increased.Alkaline salts restricted the germination rate of R. soongorica seeds, and stresses resulting from alkaline salts and high concentrations of neutral salts resulted in many deformed seedlings. The length of the radicle and germ decreased with increasing salt concentration, but certain concentrations of salt and increased p H promoted germ growth. The results of regression analysis show that salt concentration was the dominant factor inhibiting R. soongorica seed germination rate. Salinity, buffering capacity, and p H all affected embryo growth, but salinity had the most pronounced effect. Seed viability under highly saline conditions appears to be a better indicator of adaptation to saline environments than seed germination under saline conditions.展开更多
In the field of phylogenetic analyses, the rbcL gene encoded large subunit Ribulose-1,5-biphosphate carboxylase/oxygenase （Rubisco, EC4.1.1.39）, which plays a crucial role in the process of photosynthesis for most ...In the field of phylogenetic analyses, the rbcL gene encoded large subunit Ribulose-1,5-biphosphate carboxylase/oxygenase （Rubisco, EC4.1.1.39）, which plays a crucial role in the process of photosynthesis for most terrestrial plants, has been considered to be conserved; however, recent controversy regarding rbcL conservation has appeared since it was proposed to be under natural selection within all principal lineages of land plants. In this study, by examining the variation of DNA and protein sequences among 17 species in the family Tamaricaceae, three nonsynonymous mutations were identified to be under positive selection. The favored sites were located in the alph-helix domains of Rubisco, with decreased hydrophobicity and increased entropy, which could facilitate C〇 2 penetration into the active site of Rubisco. We also found that the expression level of rbcL in different genotypes of Reaumuria soongarica shifted in response to various stresses such as drought, temperature, salt, and light. This study not only sheds light on the functional/structural features of Rubisco in the evolution scenarios from 〇 3-like into C4 in Tamaricaceae but also provides useful information on directing genetic performance to enhance photosynthesis efficiency of desert plants for sustaining fragile desert ecosystems; fur-thermore, it promotes the ability to cope with desert aridification and global warming.展开更多
Reaumuria soongorica （pall.） Maxim, a perennial desert semi-shrub, is widely found in semi-arid areas of China. It shows strong tolerance to drought, high temperature and intense radiation in its natural habitat. In...Reaumuria soongorica （pall.） Maxim, a perennial desert semi-shrub, is widely found in semi-arid areas of China. It shows strong tolerance to drought, high temperature and intense radiation in its natural habitat. In the present study, photoprotective mechanism of R. soongorica was investigated by analyzing diurnal variations of gas exchange and chlorophyll fluorecence parameters during progressive soil drying. The results show that leaf water potential of R. soongorica decreased when the soil water content dropped. Diurnal patterns of net photosynthetic rate （Pn） changed from ＂two peaks＂ to ＂one peak＂ under drought stress, and the leaf water use efficiency （WUE） increased under moderate drought and declined under severe drought. Pn , the primary maximum photochemical efficiency of PSII （Fv/Fm） and the quantum efficiency of non-cyclic electron transport of PSII （ΦPSII） decreased obviously at noon, and showed a photoinhibition phenomenon. But, the non-photochemical quenching of fluorescence （NPQ） soon reached its maximum in the day and then remained almost at the high level until 17：00, indicating that the xanthophylls cycle-dependent thermal energy dissipation played an important role. Diurnal variations of the original chlorophyll fluorescence （Fo） increased at first and then decreased. The increased value of F o under drought stress indicates that there was a reversible inactivation of PSII reaction center. These results indicate that the photoprotective mechanism in R. soongorica was the photoinhibition by using both the xanthophylls cycle-dependent thermal energy dissipation and the reversible inactivation of PSII reaction center under drought stress.展开更多
Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement ...Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of R. soongorica to saline environments. R. soon- gorica was treated with 0, 100, 200 and 400 mM NaC1 solutions for 14 days. Soil salt content increased significantly by watering with high content of NaC1 solution, and no variation between 8 and 14 days during treatment. The levels ofpe- roxidation of lipid membranes （measured by malondialdehyde content） and the activities of three antioxidant enzymes （superoxide dismutase （SOD）, peroxidase （POD） and ascorbate peroxidase （APX）） increased under salt stress. Chlorophyll and carotenoid content decreased with increasing salt content. The ratio of Chl a/Chl b and carotenoid/Chl exhibited sig- nificant increase under 400 mM NaC1. However, total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase （PAL） and Chalcone isomerase （CHI） decreased under salt stress. These findings possibly suggest that R. soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducin~ the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl.展开更多
荒漠植物在自然生境中同时遭受多种环境因子的胁迫,但植物对多重胁迫因子的应答响应机理目前仍然未知。利用数字基因表达谱技术分析了荒漠植物红砂(Reaumuria soongorica)在干旱、UV-B辐射以及干旱和UV-B辐射共胁迫下基因在转录水平的...荒漠植物在自然生境中同时遭受多种环境因子的胁迫,但植物对多重胁迫因子的应答响应机理目前仍然未知。利用数字基因表达谱技术分析了荒漠植物红砂(Reaumuria soongorica)在干旱、UV-B辐射以及干旱和UV-B辐射共胁迫下基因在转录水平的表达响应。结果显示:胁迫处理的材料与对照材料相比,差异表达的基因有上调表达基因和下调表达基因,且不同胁迫中下调表达基因总数多于上调的。双重胁迫与单因子胁迫相比,差异表达基因数量明显增加,且上调表达基因的数量增多,单因子胁迫之间的表达谱比双重胁迫与单因子之间的更为相似。双重胁迫诱导了356个上调和248个下调的特异表达基因。从诱导基因的差异表达量来看,多数基因的差异表达量集中在2~5倍,同时也诱导了少数基因的高度表达(高于100倍)。差异表达基因的GO(Gene Ontology)功能富集显著性分析和KEGG(Kyoto Encyclopedia of Genes and Genomes)代谢通路分析表明,双重胁迫相比单因子胁迫,固碳作用等生物过程的表达显著性富集,且不同的代谢途径对不同的胁迫处理表现出不同程度的响应。这说明植物在基因转录水平对单因子胁迫和双重胁迫的响应机理在很大程度上存在差异。展开更多
基金supported by the National Natural Science Foundation of China (41401043, 91125025)
文摘Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral(Na Cl and Na2SO4) and two alkali(Na HCO3 and Na2CO3) salts were selected to investigate their effects on germination and recovery responses in Reaumuria soongorica. Results show that both salt types significantly reduced germination and radicle elongation. The rate of germination and emergence of R. soongorica seeds continuously decreased as salinity increased, and the time to achieve maximum germination rate was delayed. The speed of seed germination dropped rapidly as salt concentration increased.Alkaline salts restricted the germination rate of R. soongorica seeds, and stresses resulting from alkaline salts and high concentrations of neutral salts resulted in many deformed seedlings. The length of the radicle and germ decreased with increasing salt concentration, but certain concentrations of salt and increased p H promoted germ growth. The results of regression analysis show that salt concentration was the dominant factor inhibiting R. soongorica seed germination rate. Salinity, buffering capacity, and p H all affected embryo growth, but salinity had the most pronounced effect. Seed viability under highly saline conditions appears to be a better indicator of adaptation to saline environments than seed germination under saline conditions.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.31370395 and 31500266)the"One Hundred Talents"project of the Chinese Academy of Sciences(Grant No.29Y127E71)
文摘In the field of phylogenetic analyses, the rbcL gene encoded large subunit Ribulose-1,5-biphosphate carboxylase/oxygenase （Rubisco, EC4.1.1.39）, which plays a crucial role in the process of photosynthesis for most terrestrial plants, has been considered to be conserved; however, recent controversy regarding rbcL conservation has appeared since it was proposed to be under natural selection within all principal lineages of land plants. In this study, by examining the variation of DNA and protein sequences among 17 species in the family Tamaricaceae, three nonsynonymous mutations were identified to be under positive selection. The favored sites were located in the alph-helix domains of Rubisco, with decreased hydrophobicity and increased entropy, which could facilitate C〇 2 penetration into the active site of Rubisco. We also found that the expression level of rbcL in different genotypes of Reaumuria soongarica shifted in response to various stresses such as drought, temperature, salt, and light. This study not only sheds light on the functional/structural features of Rubisco in the evolution scenarios from 〇 3-like into C4 in Tamaricaceae but also provides useful information on directing genetic performance to enhance photosynthesis efficiency of desert plants for sustaining fragile desert ecosystems; fur-thermore, it promotes the ability to cope with desert aridification and global warming.
基金supported by the National NaturalScience Foundation of China (Grant No. 30800122 and 40825001)the West Light Foundation of the Chinese Academy of Sciences
文摘Reaumuria soongorica （pall.） Maxim, a perennial desert semi-shrub, is widely found in semi-arid areas of China. It shows strong tolerance to drought, high temperature and intense radiation in its natural habitat. In the present study, photoprotective mechanism of R. soongorica was investigated by analyzing diurnal variations of gas exchange and chlorophyll fluorecence parameters during progressive soil drying. The results show that leaf water potential of R. soongorica decreased when the soil water content dropped. Diurnal patterns of net photosynthetic rate （Pn） changed from ＂two peaks＂ to ＂one peak＂ under drought stress, and the leaf water use efficiency （WUE） increased under moderate drought and declined under severe drought. Pn , the primary maximum photochemical efficiency of PSII （Fv/Fm） and the quantum efficiency of non-cyclic electron transport of PSII （ΦPSII） decreased obviously at noon, and showed a photoinhibition phenomenon. But, the non-photochemical quenching of fluorescence （NPQ） soon reached its maximum in the day and then remained almost at the high level until 17：00, indicating that the xanthophylls cycle-dependent thermal energy dissipation played an important role. Diurnal variations of the original chlorophyll fluorescence （Fo） increased at first and then decreased. The increased value of F o under drought stress indicates that there was a reversible inactivation of PSII reaction center. These results indicate that the photoprotective mechanism in R. soongorica was the photoinhibition by using both the xanthophylls cycle-dependent thermal energy dissipation and the reversible inactivation of PSII reaction center under drought stress.
基金financially supported by the National Natural Science Foundation of China(31070358,91125029,31160089 and 31000181)
文摘Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of R. soongorica to saline environments. R. soon- gorica was treated with 0, 100, 200 and 400 mM NaC1 solutions for 14 days. Soil salt content increased significantly by watering with high content of NaC1 solution, and no variation between 8 and 14 days during treatment. The levels ofpe- roxidation of lipid membranes （measured by malondialdehyde content） and the activities of three antioxidant enzymes （superoxide dismutase （SOD）, peroxidase （POD） and ascorbate peroxidase （APX）） increased under salt stress. Chlorophyll and carotenoid content decreased with increasing salt content. The ratio of Chl a/Chl b and carotenoid/Chl exhibited sig- nificant increase under 400 mM NaC1. However, total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase （PAL） and Chalcone isomerase （CHI） decreased under salt stress. These findings possibly suggest that R. soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducin~ the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl.
文摘荒漠植物在自然生境中同时遭受多种环境因子的胁迫,但植物对多重胁迫因子的应答响应机理目前仍然未知。利用数字基因表达谱技术分析了荒漠植物红砂(Reaumuria soongorica)在干旱、UV-B辐射以及干旱和UV-B辐射共胁迫下基因在转录水平的表达响应。结果显示:胁迫处理的材料与对照材料相比,差异表达的基因有上调表达基因和下调表达基因,且不同胁迫中下调表达基因总数多于上调的。双重胁迫与单因子胁迫相比,差异表达基因数量明显增加,且上调表达基因的数量增多,单因子胁迫之间的表达谱比双重胁迫与单因子之间的更为相似。双重胁迫诱导了356个上调和248个下调的特异表达基因。从诱导基因的差异表达量来看,多数基因的差异表达量集中在2~5倍,同时也诱导了少数基因的高度表达(高于100倍)。差异表达基因的GO(Gene Ontology)功能富集显著性分析和KEGG(Kyoto Encyclopedia of Genes and Genomes)代谢通路分析表明,双重胁迫相比单因子胁迫,固碳作用等生物过程的表达显著性富集,且不同的代谢途径对不同的胁迫处理表现出不同程度的响应。这说明植物在基因转录水平对单因子胁迫和双重胁迫的响应机理在很大程度上存在差异。
