In recent decades,overgrazing and the warming and drying climate have resulted in significant degradation of alpine grasslands in the source region of the Yellow River.However,research into the relationships between v...In recent decades,overgrazing and the warming and drying climate have resulted in significant degradation of alpine grasslands in the source region of the Yellow River.However,research into the relationships between vegetation and soil properties has mainly focused on an overall degradation stage,and few studies have investigated which soil properties can impact vegetation change at different stages of degradation.Vegetation and soil properties were observed in the field and measured in the laboratory for different predefined stages of degradation for alpine grassland in Maduo County in the source region of the Yellow River.Results show that:1)the aboveground and belowground biomass,soil organic carbon,total nitrogen,nitrate,and ammonia content did not decrease significantly from the intact to moderate degradation stage,but decreased significantly at severe and very severe stages of degradation;2)dominant plant species shifted from gramineaes and sedges to forbs;3)the species richness and Pielou evenness indices decreased significantly at the very severe degradation stage,the Shannon-Wiener diversity index increased at the slight and moderate degradation,but decreased at the severe and very severe degradation stages;4)soil bulk density was the strongest soil driver for changes in the plant biomass and community diversity at the intact,slight and moderate degradation stages,whereas soil organic carbon and nitrate nitrogen content were the main driving factors for changes in plant biomass and diversity at the severe and very severe degradation stages.Our results suggest that there may be different interactions between soil properties and plants before and after moderate stages of degradation.展开更多
Inoculation of wheat(Triticum aestivum L.)leaves with wheat powdery mildew fungus(Blumeria graminis f.sp.tritici)induces the cell death in adventitious roots.Reactive oxygen species(ROS)play a key role in respond to b...Inoculation of wheat(Triticum aestivum L.)leaves with wheat powdery mildew fungus(Blumeria graminis f.sp.tritici)induces the cell death in adventitious roots.Reactive oxygen species(ROS)play a key role in respond to biotic stress in plants.To study the involvement of ROS and the degree of cell death in the wheat roots following inoculation,ROS levels and microstructure of root cells were analyzed in two wheat cultivars that are susceptible(Huamai 8)and resistant(Shenmai 8)to powdery mildew fungus.At 18 d after powdery mildew fungus inoculation,only Huamai 8 displayed the leaf lesions,while root cell death occurred in both varieties.Huamai 8 had a high level of ROS accumulation,which is associated with increased root cell degradation,while in Shenmai 8,there was little ROS accumulation correlating with slight root cell degradation.The molecular study about the expression levels of ROS scavenging genes(MnSOD and CAT)in wheat roots showed that these genes expression decreased after the leaves of wheat was inoculated.The difference between Huamai 8 and Shenmai 8 on subcellular localization of H2 O2 and O2^–·was corresponded with the different down-regulation of the genes encoding for superoxide dismutase and catalase in two wheat cultivars.These results suggested that ROS were involved in the process by which powdery mildew fungus induced cell death in wheat roots.展开更多
基金financially supported by the National Key Research R&D Project(2016YFC0501803)the National Natural Science Foundation of China(41771233 and 41907386)Youth Innovation Promotion Association,Chinese Academy of Sciences。
文摘In recent decades,overgrazing and the warming and drying climate have resulted in significant degradation of alpine grasslands in the source region of the Yellow River.However,research into the relationships between vegetation and soil properties has mainly focused on an overall degradation stage,and few studies have investigated which soil properties can impact vegetation change at different stages of degradation.Vegetation and soil properties were observed in the field and measured in the laboratory for different predefined stages of degradation for alpine grassland in Maduo County in the source region of the Yellow River.Results show that:1)the aboveground and belowground biomass,soil organic carbon,total nitrogen,nitrate,and ammonia content did not decrease significantly from the intact to moderate degradation stage,but decreased significantly at severe and very severe stages of degradation;2)dominant plant species shifted from gramineaes and sedges to forbs;3)the species richness and Pielou evenness indices decreased significantly at the very severe degradation stage,the Shannon-Wiener diversity index increased at the slight and moderate degradation,but decreased at the severe and very severe degradation stages;4)soil bulk density was the strongest soil driver for changes in the plant biomass and community diversity at the intact,slight and moderate degradation stages,whereas soil organic carbon and nitrate nitrogen content were the main driving factors for changes in plant biomass and diversity at the severe and very severe degradation stages.Our results suggest that there may be different interactions between soil properties and plants before and after moderate stages of degradation.
基金supported by the National Nature Science Foundation of China (31071347 and 31171469)
文摘Inoculation of wheat(Triticum aestivum L.)leaves with wheat powdery mildew fungus(Blumeria graminis f.sp.tritici)induces the cell death in adventitious roots.Reactive oxygen species(ROS)play a key role in respond to biotic stress in plants.To study the involvement of ROS and the degree of cell death in the wheat roots following inoculation,ROS levels and microstructure of root cells were analyzed in two wheat cultivars that are susceptible(Huamai 8)and resistant(Shenmai 8)to powdery mildew fungus.At 18 d after powdery mildew fungus inoculation,only Huamai 8 displayed the leaf lesions,while root cell death occurred in both varieties.Huamai 8 had a high level of ROS accumulation,which is associated with increased root cell degradation,while in Shenmai 8,there was little ROS accumulation correlating with slight root cell degradation.The molecular study about the expression levels of ROS scavenging genes(MnSOD and CAT)in wheat roots showed that these genes expression decreased after the leaves of wheat was inoculated.The difference between Huamai 8 and Shenmai 8 on subcellular localization of H2 O2 and O2^–·was corresponded with the different down-regulation of the genes encoding for superoxide dismutase and catalase in two wheat cultivars.These results suggested that ROS were involved in the process by which powdery mildew fungus induced cell death in wheat roots.
