Change in environmental conditions with altitudinal gradients induces morpho-anatomical variations in plants that have been poorly documented in intertropical regions. Five species with three life forms, cryptophyte(A...Change in environmental conditions with altitudinal gradients induces morpho-anatomical variations in plants that have been poorly documented in intertropical regions. Five species with three life forms, cryptophyte(Alchemilla procumbens, Geranium seemannii), hemicryptophyte(Acaena elongata, Lupinus montanus), and phanerophyte(Symphoricarpos microphyllus), distributed along an altitudinal gradient in the Sierra Nevada of central Mexico, were studied. The aims were to identify and evaluate their morpho-anatomical modifications under the hypothesis that the sizes of individuals and of their wood and leaf cell types decrease as elevation increases. Three individuals per species per site were collected at seven locations along the altitudinal gradient(2949-3952 m). Their morpho-anatomical characters were analyzed through multiple regression analyses. Elevation was the variable that best explained anatomical changes in the leaf and wood ofthe five species. Canopy density and potassium content in the soil also contributed to explain the variation in anatomical variables along the gradient. As elevation increased a bimodal pattern was observed in various anatomical characters as in the leaf width of A. elongata, A. procumbens and G. seemannii and in the vessel diameter of A. procumbens, G. seemannii, and L. montanus. Other features as the vessel diameter of A. elongata, the fiber length of S. microphyllus, and the ray width of A. elongata increased as the elevation increased. Anatomical traits have a tendency to decrease in size but just toward the end of the gradient, which is probably related to changes in canopy density. The plant response to the altitudinal gradient is more focused on anatomical adaptations than morphological variation; it is also species dependent.展开更多
Three photosystem I(PSⅠ)particles associated with different amounts of light-harvesting complex I(LHCI)were isolated from a phycocyanin 645(PC645)-containing cryptophyte Chroomonas placoidea by Triton X-100 sucrose g...Three photosystem I(PSⅠ)particles associated with different amounts of light-harvesting complex I(LHCI)were isolated from a phycocyanin 645(PC645)-containing cryptophyte Chroomonas placoidea by Triton X-100 sucrose gradient centrifugation.Two active PSⅠ-LHCⅠparticles(Bands 4 and 5)were resolved from thylakoids stripped of cations only,which implied that LHC migration and the adjustment of energy distribution between photosystemⅡ(PSⅡ)and PSⅠfacilitated by cations could also occur in cryptophytes,like in higher plants.Peptide analysis revealed that 19.8-,10-,and 8.3-kDa peptides corresponding toβ,α1,andα2 subunits of PC645,respectively,were present in Bands 4 and 5.Analyses of fluorescence and circular dichroism spectra and Gauss analyses revealed efficient energy couplings between PC645 and chlorophyll within both of these PSⅠ-LHCⅠparticles.The excitation energy absorbed by PC645 could be directly transferred to chlorophyll a in the PSⅠcore or via the chlorophyll a/c-protein complex of LHCⅠ.Based on these observations,we designated the two PSⅠ-LHCⅠparticles as phycocyanin-PSⅠcomplexes,which have not been reported previously.Band 4-2 was a sub-complex of Band 4 and was almost depleted of LHCⅠ(the chlorophyll a/c-protein complex was designated as Band 4-1)and PC645.Therefore,Band 4-2 was recognized as the PSⅠcore complex.Negative staining and transmission electron microscopy images of Band 4 gave a direct view that the PC645 component attached with chlorophyll-protein complexes in a regular structure as hollow ring shape.Furthermore,while previous studies have indicated that PC645 associates with PSⅡ,our results reveal that,in this cryptophytic alga,PC645 exhibits structural—but not preferential—association with PSⅠ,which provided new information about the architecture and function of the energy transfer system comprising phycobiliproteins and chlorophyll-protein complexes in cryptophytes.展开更多
文摘Change in environmental conditions with altitudinal gradients induces morpho-anatomical variations in plants that have been poorly documented in intertropical regions. Five species with three life forms, cryptophyte(Alchemilla procumbens, Geranium seemannii), hemicryptophyte(Acaena elongata, Lupinus montanus), and phanerophyte(Symphoricarpos microphyllus), distributed along an altitudinal gradient in the Sierra Nevada of central Mexico, were studied. The aims were to identify and evaluate their morpho-anatomical modifications under the hypothesis that the sizes of individuals and of their wood and leaf cell types decrease as elevation increases. Three individuals per species per site were collected at seven locations along the altitudinal gradient(2949-3952 m). Their morpho-anatomical characters were analyzed through multiple regression analyses. Elevation was the variable that best explained anatomical changes in the leaf and wood ofthe five species. Canopy density and potassium content in the soil also contributed to explain the variation in anatomical variables along the gradient. As elevation increased a bimodal pattern was observed in various anatomical characters as in the leaf width of A. elongata, A. procumbens and G. seemannii and in the vessel diameter of A. procumbens, G. seemannii, and L. montanus. Other features as the vessel diameter of A. elongata, the fiber length of S. microphyllus, and the ray width of A. elongata increased as the elevation increased. Anatomical traits have a tendency to decrease in size but just toward the end of the gradient, which is probably related to changes in canopy density. The plant response to the altitudinal gradient is more focused on anatomical adaptations than morphological variation; it is also species dependent.
基金Supported by the Natural Science Foundation of Shandong Province(No.ZR2018LD009)。
文摘Three photosystem I(PSⅠ)particles associated with different amounts of light-harvesting complex I(LHCI)were isolated from a phycocyanin 645(PC645)-containing cryptophyte Chroomonas placoidea by Triton X-100 sucrose gradient centrifugation.Two active PSⅠ-LHCⅠparticles(Bands 4 and 5)were resolved from thylakoids stripped of cations only,which implied that LHC migration and the adjustment of energy distribution between photosystemⅡ(PSⅡ)and PSⅠfacilitated by cations could also occur in cryptophytes,like in higher plants.Peptide analysis revealed that 19.8-,10-,and 8.3-kDa peptides corresponding toβ,α1,andα2 subunits of PC645,respectively,were present in Bands 4 and 5.Analyses of fluorescence and circular dichroism spectra and Gauss analyses revealed efficient energy couplings between PC645 and chlorophyll within both of these PSⅠ-LHCⅠparticles.The excitation energy absorbed by PC645 could be directly transferred to chlorophyll a in the PSⅠcore or via the chlorophyll a/c-protein complex of LHCⅠ.Based on these observations,we designated the two PSⅠ-LHCⅠparticles as phycocyanin-PSⅠcomplexes,which have not been reported previously.Band 4-2 was a sub-complex of Band 4 and was almost depleted of LHCⅠ(the chlorophyll a/c-protein complex was designated as Band 4-1)and PC645.Therefore,Band 4-2 was recognized as the PSⅠcore complex.Negative staining and transmission electron microscopy images of Band 4 gave a direct view that the PC645 component attached with chlorophyll-protein complexes in a regular structure as hollow ring shape.Furthermore,while previous studies have indicated that PC645 associates with PSⅡ,our results reveal that,in this cryptophytic alga,PC645 exhibits structural—but not preferential—association with PSⅠ,which provided new information about the architecture and function of the energy transfer system comprising phycobiliproteins and chlorophyll-protein complexes in cryptophytes.
