Serving as one of the largest rivers in terms of both sediment and organic carbon transport fluxes in the world,the Yellow River plays a crucial role in regional biogeochemical process as well as in the global carbon ...Serving as one of the largest rivers in terms of both sediment and organic carbon transport fluxes in the world,the Yellow River plays a crucial role in regional biogeochemical process as well as in the global carbon cycle.However,although a large number of studies have been carried out on the flux,composition,source and seasonal variation of total particulate organic carbon in the Yellow River so far,studies on molecular biomarkers at different spatial and temporal scales are still scarce.In this study,we focus on the molecular and hydrogen isotopic properties of leaf wax n-alkanes among different types of samples which obtained from different seasons(flood vs.non-flood)along the lower Yellow River.The molecular distribution of n-alkanes show that the riparian topsoils are subject to inputs from the overlying vegetation,while the suspended sediments from the flood season are characterized by the mixing of soil materials which originate from various stratigraphy with different ages on the Chinese Loess Plateau.Due to the contrasting hydrodynamic conditions,the n-alkanes in suspended sediments also show distinct molecular composition between flood and non-flood seasons.Additionally,considering the effect of climatic factors,the proportion of monocots in flood-season suspended sediments is calculated from a semi-quantitative perspective using δ^(2)H_(wax).Our findings may bring to light new considerations for the interpretation of leaf wax proxies in studies of organic matter sources of Yellow River.展开更多
Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-a...Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water （δDsw）, leaf water （δDlw）, and leaf wax n-alkane （δDn-alkane） for woods and grasses. We found no significant differences in the δD values of soil water （P = 0.82） and leaf water （P= 0.74） between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.展开更多
Numerous field studies have shown that leaf wax n-alkane δD values(δD_(n-alkane))can be used as a proxy for paleoelevation reconstruction.However,the lack of systematic global analysis of δD_(n-alkane) values with ...Numerous field studies have shown that leaf wax n-alkane δD values(δD_(n-alkane))can be used as a proxy for paleoelevation reconstruction.However,the lack of systematic global analysis of δD_(n-alkane) values with respect to altitude limits the reliability of δD_(n-alkane )values for paleoaltimetry at the global scale.In this study,we analyzed the variation of δD_(n-alkane) values with altitude in terrestrial higher plants based upon our compiled globalδDn-alkane database.The general decrease in δD_(n-alkane) values with altitude corresponds to the variation in precipitationδD(δD_(prec))with altitude,suggesting that the δD_(n-alkanevalues) effectively reflect δD_(prec) values.When eliminating the effect of latitude at the global scale,the global δD_(n-alkane)-altitude lapse rate for all species was-1.01±0.10‰(100 m)-1,while these lapse rates were-1.03±0.13‰ and-0.47±0.13‰(100 m)^(-1) for dicots and monocots,respectively.Our study reveals that it is reliable to use δD_(n-alkanevalues) to gain information about paleoelevation at the global scale,and the global δD_(n-alkane-altitude) lapse rates provide an alternative to reconstruct paleoelevation at some δD_(n-alkane)-uninvestigated areas.展开更多
The compound-specific stable carbon isotope compositions(δ^(13)C) of leaf wax n-alkanes from two short sediment cores recovered off the Pearl River estuary(PRE) were analyzed to check for their capability of indicati...The compound-specific stable carbon isotope compositions(δ^(13)C) of leaf wax n-alkanes from two short sediment cores recovered off the Pearl River estuary(PRE) were analyzed to check for their capability of indicating decadal scale catchment environmental change. Sedimentary long-chain n-alkanes exhibited an odd-over-even predominance, with a maximum at n-C_(29) or n-C_(31), indicating their leaf wax origin was from vascular plants. The δ^(13)C values of C_(29) and C_(31) n-alkane in all the sediment samples were in the range of -28.8‰ to -31.2‰, consistent with the C_3 plant-dominated vegetation in the Pearl River catchments. The time series of δ^(13)C records from the two cores were comparable and displayed a decreasing trend from the early 20 th century to the end of the 1970s, followed by a reversal in that change leading to continued increase for ca. 15 years. After being corrected for the effect of atmospheric CO_2 rise and δ^(13)C_(atm) decline, the δ^(13)C_(29) records largely retained their raw changing pattern; the post-1980 increase being more conspicuous. The slightly decreasing trend in corrected δ^(13)C records before around 1980 may have been caused by an increase in precipitation, whereas the subsequent increase of δ^(13)C is likely associated with the observed dry climate and/or intensive anthropogenic deforestation. Our results thus demonstrate that leaf wax n-alkanes buried in the sediments off the PRE may well reflect change in the regional climate and/or human activity in the river catchments over the past century.展开更多
Plant biomarkers, such as hydrocarbon waxes, are frequently found in various sediments and could be adopted as paleovegetation and paleoclimate indicators. Nevertheless, scarce researches have focused on leaf waxes in...Plant biomarkers, such as hydrocarbon waxes, are frequently found in various sediments and could be adopted as paleovegetation and paleoclimate indicators. Nevertheless, scarce researches have focused on leaf waxes in higher plants of alpine region.Herein, hydrocarbon leaf wax components of Salix oritrepha, which flourish in Nianbaoyeze Mountains in eastern Tibetan Plateau were fully discussed. The n-alkane distribution in leaves ranges from n-C_(21) to nC_(29) with maxima at n-C_(25), which were entirely different with Salix taxa displayed in previous surveys in non-alpine regions. The unusual even carbon nalkenes from n-C_(22:1) to n-C_(30:1), which were thought to appear only in aquatic organisms, were firstly reported in an alpine plant. Additionally, iso-(2-methyl) alkanes, ranging from i-C_(23) to i-C_(29) with maxima at i-C_(25), which have been commonly reported in microorganisms, were also identified in an alpine plant for the first time. Unusual hydrocarbon distribution detected in Salix oritrepha leaf from Nianbaoyeze Mountains is most likely due to the extreme environment in such alpine region.展开更多
White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defe...White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defensive enzymes activities of immune(Chrysanthemum makinoi var.wakasaense)and highly susceptible(Ajania shiwogiku var.kinokuniense)species were compared.Trichome density of two species was markedly different,negatively associated with plant resistance to P.horiana.Total wax load in C.makinoi var.wakasaense was two times more than that in A.shiwogiku var.kinokuniense.The wax composition in immune one was abundant in esters and primary alcohols.Superoxide dismutase(SOD,EC 1.15.1.1),peroxidase(POD,EC 1.11.1.7),polyphenoloxidase(PPO,EC 1.14.18.1 or EC 1.10.3.2)and phenylalanine ammonia lyase(PAL,EC 4.3.1.5)activitieswere investigated.In C.makinoi var.wakasaense,the activity of SOD and POD increased rapidly after inoculation,whichmight be non-host induced reactive oxygen species(ROS)activated antioxidant enzymes,however SOD and POD remained a low and steady level in the highly susceptible one after inoculation.Quick increase in PPO activities after inoculation was observed in both species,however it remained higher in C.makinoi var.wakasaense at the late period of inoculation.PAL in C.makinoi var.wakasaense was induced after pathogen inoculation,but not in A.shiwogiku var.kinokuniense,suggesting that these two enzymes might contribute to the resistance to P.horiana.展开更多
The rapid growth and early development period of the dual-scale surface topography was studied on the adaxial leaf surfaces of two aspen tree species with non-wetting leaves: the columnar European aspen (Populus tremu...The rapid growth and early development period of the dual-scale surface topography was studied on the adaxial leaf surfaces of two aspen tree species with non-wetting leaves: the columnar European aspen (Populus tremula “Erecta”) and quaking aspen (Populus tremuloides). Particular attention was focused on the formation of micro- and nano-scale asperities on their cuticles, which was correlated with the development of superhydrophobic wetting behaviour. Measurements of the wetting properties (contact angle and tilt-angle) provided an indication of the degree of hydrophobicity of their cuticles. Scanning electron microscopy and optical profilometry micrographs were used to follow the growth and major morphological changes of micro-scale papillae and nano-scale epicuticular wax (ECW) crystals, which led to a significant improvement in non-wetting behaviour. Both species exhibited syntopism in the form of small and larger nano-scale ECW platelet morphologies. These findings provide additional support for earlier suggestions that due to fluctuations in leaf hydrophobicity throughout the growing season, canopy storage capacity may also vary considerably throughout this time period.展开更多
Leaf traits, structure and water status of Conocarpus lancifolius, a Combretaceae were investigated under semi-arid conditions. The leaf traits examined included leaf area and thickness, stomatal distribution, sclerop...Leaf traits, structure and water status of Conocarpus lancifolius, a Combretaceae were investigated under semi-arid conditions. The leaf traits examined included leaf area and thickness, stomatal distribution, sclerophylly, succulence and relative water content. Additionally, the types of secretory structures, histochemistry of trichomes, and chemical nature of the cuticlular waxes were evaluated. Leaves showed xerophytic characteristics including a high degree of sclerophylly, thick cuticle and outer epidermal cell wall, low relative water content and high trichome density on younger leaves. The species has two types of trichomes;a secretory, short-stalked capitate trichome and a non-secretory trichome with a bulbous base and a pointed tip. The leaves also have a pair of extrafloral nectaries on both sides of the distal end of the petiole, 3-4 pairs near the leaf apex and two secretory ducts or cavities on mature leaves that secreted polysaccharides, epicuticlar waxes and polyphenols. Compared to young leaves mature leaves had almost 3 times total cuticular wax deposit or load. The most abundant fatty acids were palmitic, stearic, nondecanoic, behenic and arachidic acids. The leaf traits and structures are discussed in relation to semi-arid habitat.展开更多
基金supported by the Chinese Academy of Sciences(Grant No.ZDBSLY-DQC033)the National Natural Science Foundation of China(Grant Nos.42073017&42030512)。
文摘Serving as one of the largest rivers in terms of both sediment and organic carbon transport fluxes in the world,the Yellow River plays a crucial role in regional biogeochemical process as well as in the global carbon cycle.However,although a large number of studies have been carried out on the flux,composition,source and seasonal variation of total particulate organic carbon in the Yellow River so far,studies on molecular biomarkers at different spatial and temporal scales are still scarce.In this study,we focus on the molecular and hydrogen isotopic properties of leaf wax n-alkanes among different types of samples which obtained from different seasons(flood vs.non-flood)along the lower Yellow River.The molecular distribution of n-alkanes show that the riparian topsoils are subject to inputs from the overlying vegetation,while the suspended sediments from the flood season are characterized by the mixing of soil materials which originate from various stratigraphy with different ages on the Chinese Loess Plateau.Due to the contrasting hydrodynamic conditions,the n-alkanes in suspended sediments also show distinct molecular composition between flood and non-flood seasons.Additionally,considering the effect of climatic factors,the proportion of monocots in flood-season suspended sediments is calculated from a semi-quantitative perspective using δ^(2)H_(wax).Our findings may bring to light new considerations for the interpretation of leaf wax proxies in studies of organic matter sources of Yellow River.
文摘Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water （δDsw）, leaf water （δDlw）, and leaf wax n-alkane （δDn-alkane） for woods and grasses. We found no significant differences in the δD values of soil water （P = 0.82） and leaf water （P= 0.74） between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.
基金supported by the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-DQC001,132B61KYSB20170005,ZDBS-LY-DQC033)the National Natural Science Foundation of China(Grant No.41420104008)。
文摘Numerous field studies have shown that leaf wax n-alkane δD values(δD_(n-alkane))can be used as a proxy for paleoelevation reconstruction.However,the lack of systematic global analysis of δD_(n-alkane) values with respect to altitude limits the reliability of δD_(n-alkane )values for paleoaltimetry at the global scale.In this study,we analyzed the variation of δD_(n-alkane) values with altitude in terrestrial higher plants based upon our compiled globalδDn-alkane database.The general decrease in δD_(n-alkane) values with altitude corresponds to the variation in precipitationδD(δD_(prec))with altitude,suggesting that the δD_(n-alkanevalues) effectively reflect δD_(prec) values.When eliminating the effect of latitude at the global scale,the global δD_(n-alkane)-altitude lapse rate for all species was-1.01±0.10‰(100 m)-1,while these lapse rates were-1.03±0.13‰ and-0.47±0.13‰(100 m)^(-1) for dicots and monocots,respectively.Our study reveals that it is reliable to use δD_(n-alkanevalues) to gain information about paleoelevation at the global scale,and the global δD_(n-alkane-altitude) lapse rates provide an alternative to reconstruct paleoelevation at some δD_(n-alkane)-uninvestigated areas.
基金supported by the National Natural Science Foundation of China(Grant Nos.41061160498&41276072)
文摘The compound-specific stable carbon isotope compositions(δ^(13)C) of leaf wax n-alkanes from two short sediment cores recovered off the Pearl River estuary(PRE) were analyzed to check for their capability of indicating decadal scale catchment environmental change. Sedimentary long-chain n-alkanes exhibited an odd-over-even predominance, with a maximum at n-C_(29) or n-C_(31), indicating their leaf wax origin was from vascular plants. The δ^(13)C values of C_(29) and C_(31) n-alkane in all the sediment samples were in the range of -28.8‰ to -31.2‰, consistent with the C_3 plant-dominated vegetation in the Pearl River catchments. The time series of δ^(13)C records from the two cores were comparable and displayed a decreasing trend from the early 20 th century to the end of the 1970s, followed by a reversal in that change leading to continued increase for ca. 15 years. After being corrected for the effect of atmospheric CO_2 rise and δ^(13)C_(atm) decline, the δ^(13)C_(29) records largely retained their raw changing pattern; the post-1980 increase being more conspicuous. The slightly decreasing trend in corrected δ^(13)C records before around 1980 may have been caused by an increase in precipitation, whereas the subsequent increase of δ^(13)C is likely associated with the observed dry climate and/or intensive anthropogenic deforestation. Our results thus demonstrate that leaf wax n-alkanes buried in the sediments off the PRE may well reflect change in the regional climate and/or human activity in the river catchments over the past century.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41301224, 41601195)Jiangsu Overseas Research & Training Program for University Prominent Young & Middle-aged Teachers and Presidents
文摘Plant biomarkers, such as hydrocarbon waxes, are frequently found in various sediments and could be adopted as paleovegetation and paleoclimate indicators. Nevertheless, scarce researches have focused on leaf waxes in higher plants of alpine region.Herein, hydrocarbon leaf wax components of Salix oritrepha, which flourish in Nianbaoyeze Mountains in eastern Tibetan Plateau were fully discussed. The n-alkane distribution in leaves ranges from n-C_(21) to nC_(29) with maxima at n-C_(25), which were entirely different with Salix taxa displayed in previous surveys in non-alpine regions. The unusual even carbon nalkenes from n-C_(22:1) to n-C_(30:1), which were thought to appear only in aquatic organisms, were firstly reported in an alpine plant. Additionally, iso-(2-methyl) alkanes, ranging from i-C_(23) to i-C_(29) with maxima at i-C_(25), which have been commonly reported in microorganisms, were also identified in an alpine plant for the first time. Unusual hydrocarbon distribution detected in Salix oritrepha leaf from Nianbaoyeze Mountains is most likely due to the extreme environment in such alpine region.
基金supported by Jiangsu Agriculture Science and Technology Innovation Fund[Grant No.CX(18)2020]the National Natural Science Foundation of China(Grant Nos.31672192 and 31700620)+1 种基金the National Key Research and Development Program of China(Grant No.2018YFD1000402)the Fundamental Research Funds for the Central Universities(Grant No.KJQN201812).
文摘White rust caused by Puccinia horiana is a destructive disease of chrysanthemum plants.To better understand the resistance mechanisms of composite species to this disease,the leaf cuticular traits,antioxidant and defensive enzymes activities of immune(Chrysanthemum makinoi var.wakasaense)and highly susceptible(Ajania shiwogiku var.kinokuniense)species were compared.Trichome density of two species was markedly different,negatively associated with plant resistance to P.horiana.Total wax load in C.makinoi var.wakasaense was two times more than that in A.shiwogiku var.kinokuniense.The wax composition in immune one was abundant in esters and primary alcohols.Superoxide dismutase(SOD,EC 1.15.1.1),peroxidase(POD,EC 1.11.1.7),polyphenoloxidase(PPO,EC 1.14.18.1 or EC 1.10.3.2)and phenylalanine ammonia lyase(PAL,EC 4.3.1.5)activitieswere investigated.In C.makinoi var.wakasaense,the activity of SOD and POD increased rapidly after inoculation,whichmight be non-host induced reactive oxygen species(ROS)activated antioxidant enzymes,however SOD and POD remained a low and steady level in the highly susceptible one after inoculation.Quick increase in PPO activities after inoculation was observed in both species,however it remained higher in C.makinoi var.wakasaense at the late period of inoculation.PAL in C.makinoi var.wakasaense was induced after pathogen inoculation,but not in A.shiwogiku var.kinokuniense,suggesting that these two enzymes might contribute to the resistance to P.horiana.
文摘The rapid growth and early development period of the dual-scale surface topography was studied on the adaxial leaf surfaces of two aspen tree species with non-wetting leaves: the columnar European aspen (Populus tremula “Erecta”) and quaking aspen (Populus tremuloides). Particular attention was focused on the formation of micro- and nano-scale asperities on their cuticles, which was correlated with the development of superhydrophobic wetting behaviour. Measurements of the wetting properties (contact angle and tilt-angle) provided an indication of the degree of hydrophobicity of their cuticles. Scanning electron microscopy and optical profilometry micrographs were used to follow the growth and major morphological changes of micro-scale papillae and nano-scale epicuticular wax (ECW) crystals, which led to a significant improvement in non-wetting behaviour. Both species exhibited syntopism in the form of small and larger nano-scale ECW platelet morphologies. These findings provide additional support for earlier suggestions that due to fluctuations in leaf hydrophobicity throughout the growing season, canopy storage capacity may also vary considerably throughout this time period.
文摘Leaf traits, structure and water status of Conocarpus lancifolius, a Combretaceae were investigated under semi-arid conditions. The leaf traits examined included leaf area and thickness, stomatal distribution, sclerophylly, succulence and relative water content. Additionally, the types of secretory structures, histochemistry of trichomes, and chemical nature of the cuticlular waxes were evaluated. Leaves showed xerophytic characteristics including a high degree of sclerophylly, thick cuticle and outer epidermal cell wall, low relative water content and high trichome density on younger leaves. The species has two types of trichomes;a secretory, short-stalked capitate trichome and a non-secretory trichome with a bulbous base and a pointed tip. The leaves also have a pair of extrafloral nectaries on both sides of the distal end of the petiole, 3-4 pairs near the leaf apex and two secretory ducts or cavities on mature leaves that secreted polysaccharides, epicuticlar waxes and polyphenols. Compared to young leaves mature leaves had almost 3 times total cuticular wax deposit or load. The most abundant fatty acids were palmitic, stearic, nondecanoic, behenic and arachidic acids. The leaf traits and structures are discussed in relation to semi-arid habitat.
