Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified ...Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified the novel function of R2R3-MYB transcription factors CsRAXs in regulating cucumber leaf size and fruiting ability.Csrax5 single mutant exhibited enlarged leaf size and stem diameter,and Csrax1/2/5 triple mutant displayed further enlargement phenotype.Overexpression of CsRAX1 or CsRAX5 gave rise to smaller leaf and thinner stem.The fruiting ability of Csrax1/2/5 plants was significantly enhanced,while that of CsRAX5 overexpression lines was greatly weakened.Similarly,cell number and free auxin level were elevated in mutant plants while decreased in overexpression lines.Biochemical data indicated that CsRAX1/5 directly promoted the expression of auxin glucosyltransferase gene CsUGT74E2.Therefore,our data suggested that CsRAXs function as repressors for leaf size development by promoting auxin glycosylation to decrease free auxin level and cell division in cucumber.Our findings provide new gene targets for cucumber breeding with increased leaf size and crop yield.展开更多
Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Pr...Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing.In this study,we investigated whether there were other differences between sexes in leaf size,shape and ecophysiology,and if those differences were connected with adaptations and reproductive roles in the sexes of A.tomentosa.Methods Physical and chemical features of young and old leaves originating from female and male A.tomentosa plants growing in two disjunct populations in eastern Australia were measured.We determined leaf area,perimeter length,serration,circularity,aspect ratio(AR),roundness and the ecophysiological factors:specific leaf area,dry matter content,leaf moisture,relative water content,δ^(13)C,δ^(15)N isotope compositions,carbon and nitrogen contents and C:N ratio.Leaf lobing,the degree of lamina damage and the content of photosynthetic pigments were also determined.Important Findings In both populations studied,the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area,perimeter length,circularity,AR and roundness.Contrary to expectations,males from both populations had a greater leaf area that was independent of leaf age.Male leaves were more lobed with a longer perimeter,but they were less elongated and less serrated.Only small differences between female and male leaves were observed for the ecophysiological factors.The degree of leaf damage differed between sexes but also with population.Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors.However,leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology,because females had greater leaf serration in comparison to males despite the smaller leaf area.展开更多
Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exert...Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exerts a significant influence on forest community diversity and structure,as well as ecosystem function and stability.Notable variation in herbivory has been detected both among and within plant species.For decades,many hypotheses have been proposed to explain such variations,including both biotic and abiotic variables.However,most studies have considered only one or several of these hypotheses by focusing on a few potential variables,and their results were usually inconsistent;thus,the factors driving herbivory remain unclear.In this study,we examined leaf herbivory by insects of woody species seedlings in a subtropical forest in southwestern China over two seasons.In total,24 potential variables that represented abiotic resource availability,characters of individual seedlings,conspecific and heterospecific species,and the whole seedling community were selected to test several commonly discussed alternative herbivory hypotheses.Overall,our findings showed that the plant apparency hypothesis was more supported than the other hypotheses in explaining insect seedling herbivory.Our results further indicated that the mechanisms and causes of insect herbivory are complex,multifactorial,species-specific and vary with seasons,indicating that there may be no uniform rules in explaining herbivory for all seedlings.Consequently,such complexity may play an important role in promoting species coexistence and biodiversity maintenance in seedling communities,which may further translate into the following generation of saplings or even adult communities.Changes in the community of insect herbivores and/or variables influencing insect herbivory,may disrupt stability of the original seedling community,thus affecting the regeneration and development of the entire forest community.Therefore,we suggest that issues related to insect herbivory should be considered when developing forest management and conservation.展开更多
Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have...Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, we expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.展开更多
Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fa...Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.展开更多
Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollu...Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.展开更多
基金supported by grants from the National Natural Science Foundation of China[32025033,31930097 and 32372699]Pinduoduo-China Agricultural University Research Fund[PC2023B01002].
文摘Leaves are the main photosynthesis organ that directly determines crop yield and biomass.Dissecting the regulatory mechanism of leaf development is crucial for food security and ecosystem turn-over.Here,we identified the novel function of R2R3-MYB transcription factors CsRAXs in regulating cucumber leaf size and fruiting ability.Csrax5 single mutant exhibited enlarged leaf size and stem diameter,and Csrax1/2/5 triple mutant displayed further enlargement phenotype.Overexpression of CsRAX1 or CsRAX5 gave rise to smaller leaf and thinner stem.The fruiting ability of Csrax1/2/5 plants was significantly enhanced,while that of CsRAX5 overexpression lines was greatly weakened.Similarly,cell number and free auxin level were elevated in mutant plants while decreased in overexpression lines.Biochemical data indicated that CsRAX1/5 directly promoted the expression of auxin glucosyltransferase gene CsUGT74E2.Therefore,our data suggested that CsRAXs function as repressors for leaf size development by promoting auxin glycosylation to decrease free auxin level and cell division in cucumber.Our findings provide new gene targets for cucumber breeding with increased leaf size and crop yield.
基金supported by the Department of Education and Training,Australian Government(Endeavour Research Fellowship,2017 to M.R.),the University of New England in Armidale,Australia and the Institute of Dendrology,Polish Academy of Sciences,Poland.
文摘Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing.In this study,we investigated whether there were other differences between sexes in leaf size,shape and ecophysiology,and if those differences were connected with adaptations and reproductive roles in the sexes of A.tomentosa.Methods Physical and chemical features of young and old leaves originating from female and male A.tomentosa plants growing in two disjunct populations in eastern Australia were measured.We determined leaf area,perimeter length,serration,circularity,aspect ratio(AR),roundness and the ecophysiological factors:specific leaf area,dry matter content,leaf moisture,relative water content,δ^(13)C,δ^(15)N isotope compositions,carbon and nitrogen contents and C:N ratio.Leaf lobing,the degree of lamina damage and the content of photosynthetic pigments were also determined.Important Findings In both populations studied,the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area,perimeter length,circularity,AR and roundness.Contrary to expectations,males from both populations had a greater leaf area that was independent of leaf age.Male leaves were more lobed with a longer perimeter,but they were less elongated and less serrated.Only small differences between female and male leaves were observed for the ecophysiological factors.The degree of leaf damage differed between sexes but also with population.Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors.However,leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology,because females had greater leaf serration in comparison to males despite the smaller leaf area.
基金supported by the National Natural Science Foundation of China(Nos.32171533 and 31971444)Anhui Provincial Natural Science Foundation(No.2208085J28)。
文摘Insect herbivory is ubiquitous in various ecosystems,and directly influences the growth and survival of individual plants,especially during their vulnerable early life stages like the seedling phase.This,in turn,exerts a significant influence on forest community diversity and structure,as well as ecosystem function and stability.Notable variation in herbivory has been detected both among and within plant species.For decades,many hypotheses have been proposed to explain such variations,including both biotic and abiotic variables.However,most studies have considered only one or several of these hypotheses by focusing on a few potential variables,and their results were usually inconsistent;thus,the factors driving herbivory remain unclear.In this study,we examined leaf herbivory by insects of woody species seedlings in a subtropical forest in southwestern China over two seasons.In total,24 potential variables that represented abiotic resource availability,characters of individual seedlings,conspecific and heterospecific species,and the whole seedling community were selected to test several commonly discussed alternative herbivory hypotheses.Overall,our findings showed that the plant apparency hypothesis was more supported than the other hypotheses in explaining insect seedling herbivory.Our results further indicated that the mechanisms and causes of insect herbivory are complex,multifactorial,species-specific and vary with seasons,indicating that there may be no uniform rules in explaining herbivory for all seedlings.Consequently,such complexity may play an important role in promoting species coexistence and biodiversity maintenance in seedling communities,which may further translate into the following generation of saplings or even adult communities.Changes in the community of insect herbivores and/or variables influencing insect herbivory,may disrupt stability of the original seedling community,thus affecting the regeneration and development of the entire forest community.Therefore,we suggest that issues related to insect herbivory should be considered when developing forest management and conservation.
文摘Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, we expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.
基金supported by the National Basic Research Program of China(973 Program,2012CB416904)partially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.
基金The National Natural Science Foundation of China (No. 30570338) the Natural Science Foundation of Beijing (No. 6053026) andthe Ministry of Education, China(No. 20040027020).
文摘Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.
