interactions,many flowers are known to display their attractive qualities,such as scent emission,flower rewards and floral vertical direction,in a rhythmic fashion.However,less is known about how plants regulate the r...interactions,many flowers are known to display their attractive qualities,such as scent emission,flower rewards and floral vertical direction,in a rhythmic fashion.However,less is known about how plants regulate the relationship between these flower traits to adapt to pollinator visiting behavior and increase reproduction success.Here we investigated the adaptive significance of the flower bending from erect to downward in Trifolium repens.We observed the flowering dynamic characteristics(changes of vertical direction of florets,flowering number,pollen grain numbers,pollen viability and stigma receptivity over time after blossom)and the factors affecting the rate of flower bending in T.repens.Then we altered the vertical direction of florets in inflorescence of different types(upright and downward),and compared the pollinator behaviors and female reproductive success.Our results showed that florets opened sequentially in inflorescence,and then bend downwards slowly after flowering.The bending speed of florets was mainly influenced by pollination,and bending angle increased with the prolongation of flowering time,while the pollen germination rate,stigma receptivity and nectar secretion has a rhythm of“lowhigh-low”during the whole period with the time going.The visiting frequency of all the four species of pollinators on upward flowers was significantly higher than that of downward flowers,and they especially prefer to visit flowers with a bending angle of 30°–60°,when the flowers was exactly of the highest flower rewards(nectar secretion and number of pollen grains),stigma receptivity and pollen germination rate.The seed set ratio and fruit set ratio of upward flowers were significantly higher than downward flowers,but significantly lower than unmanipulated flowers.Our results indicated that the T.repens could increase female and male fitness by accurate pollination.The most suitable flower angle saves pollinators’visiting energy and enables them to obtain the highest nectar rewards.This coordination between plants and pollinators maximizes the interests of them,which is a crucial factor in initiating specialized plant-pollinator relationships.展开更多
The suitability of models for describing the clonal growth of Trifolium repens population was discussed.The results showed that deterministic models were inadequate for describing its clonal growth,but the diffusion m...The suitability of models for describing the clonal growth of Trifolium repens population was discussed.The results showed that deterministic models were inadequate for describing its clonal growth,but the diffusion models and the randomwalk models suited for the clonal growth characteristics of the population.And it was found that random-walk models were better than diffusion models for describing a population in an environment with rich natural resources,and the latter was better in a poor environment.展开更多
Starting from sissotrin (1), a natural isoflavonoid isolated from Trifolium baccarinii (Fabaceae), one new semisynthetic derivative, 6-nitrobiochanin A (1b) and two known derivatives, 8-nitrobiochanin A (1a) and 2&quo...Starting from sissotrin (1), a natural isoflavonoid isolated from Trifolium baccarinii (Fabaceae), one new semisynthetic derivative, 6-nitrobiochanin A (1b) and two known derivatives, 8-nitrobiochanin A (1a) and 2",3",4",6"-tetraacetylsissotrin (1c) have been obtained after performing nitration and acetylation reactions. Their structures were assigned after interpretation of their spectrometric (HR-ESI-MS) and spectroscopic (NMR 1D and 2D) data and by comparison with those reported in the literature. The substrate as well as the semisynthetic derivatives were evaluated for their antibacterial activities against six strains. The results reveal that they are inactive or weakly active on the strains tested with the exception of 8-nitrobiochanin A (1a) which showed moderate activity (MIC = 62.5 μg∙mL<sup>−1</sup>) on Staphylococcus aureus ATCC 43300.展开更多
Three ethylene diurea(EDU) concentrations(0,150 and 300 mg/L) were used to evaluate the negative impact of ozone(O3) on two cultivars of Trifolium repens L.cv.Vardan and Bundel grown under natural field conditions in ...Three ethylene diurea(EDU) concentrations(0,150 and 300 mg/L) were used to evaluate the negative impact of ozone(O3) on two cultivars of Trifolium repens L.cv.Vardan and Bundel grown under natural field conditions in a suburban area of Varanasi,India.Mean O3 concentrations varied from 30.3 to 46.6 μg/L during the experimental period.Higher photosynthetic pigments and ascorbic acid concentrations were noticed in both EDU-treated cultivars over non-EDU-treated ones,but a reverse trend was found for lipid peroxidation.Growth parameters and biomass also showed increments under EDU treatment of both cultivars.The ratio of variable fluorescence to maximum fluorescence increased significantly in Vardan but not in Bundel upon EDU treatment.Results revealed that EDU concentration of 300 mg/L was more effective to combat the oxidative stress as well as protecting plants from O3 injury symptoms.The test cultivar Vardan is relatively sensitive to O3,thereby can be used as a bioindicator of O3 pollution in areas having higher O3 concentrations.Results also indicated that Bundel has more efficient antioxidant defense system than Vardan and hence was more tolerant to O3 stress.展开更多
基金the National Natural Science Foundation of China,Grant Nos.31860051 and 31360044.
文摘interactions,many flowers are known to display their attractive qualities,such as scent emission,flower rewards and floral vertical direction,in a rhythmic fashion.However,less is known about how plants regulate the relationship between these flower traits to adapt to pollinator visiting behavior and increase reproduction success.Here we investigated the adaptive significance of the flower bending from erect to downward in Trifolium repens.We observed the flowering dynamic characteristics(changes of vertical direction of florets,flowering number,pollen grain numbers,pollen viability and stigma receptivity over time after blossom)and the factors affecting the rate of flower bending in T.repens.Then we altered the vertical direction of florets in inflorescence of different types(upright and downward),and compared the pollinator behaviors and female reproductive success.Our results showed that florets opened sequentially in inflorescence,and then bend downwards slowly after flowering.The bending speed of florets was mainly influenced by pollination,and bending angle increased with the prolongation of flowering time,while the pollen germination rate,stigma receptivity and nectar secretion has a rhythm of“lowhigh-low”during the whole period with the time going.The visiting frequency of all the four species of pollinators on upward flowers was significantly higher than that of downward flowers,and they especially prefer to visit flowers with a bending angle of 30°–60°,when the flowers was exactly of the highest flower rewards(nectar secretion and number of pollen grains),stigma receptivity and pollen germination rate.The seed set ratio and fruit set ratio of upward flowers were significantly higher than downward flowers,but significantly lower than unmanipulated flowers.Our results indicated that the T.repens could increase female and male fitness by accurate pollination.The most suitable flower angle saves pollinators’visiting energy and enables them to obtain the highest nectar rewards.This coordination between plants and pollinators maximizes the interests of them,which is a crucial factor in initiating specialized plant-pollinator relationships.
文摘The suitability of models for describing the clonal growth of Trifolium repens population was discussed.The results showed that deterministic models were inadequate for describing its clonal growth,but the diffusion models and the randomwalk models suited for the clonal growth characteristics of the population.And it was found that random-walk models were better than diffusion models for describing a population in an environment with rich natural resources,and the latter was better in a poor environment.
文摘Starting from sissotrin (1), a natural isoflavonoid isolated from Trifolium baccarinii (Fabaceae), one new semisynthetic derivative, 6-nitrobiochanin A (1b) and two known derivatives, 8-nitrobiochanin A (1a) and 2",3",4",6"-tetraacetylsissotrin (1c) have been obtained after performing nitration and acetylation reactions. Their structures were assigned after interpretation of their spectrometric (HR-ESI-MS) and spectroscopic (NMR 1D and 2D) data and by comparison with those reported in the literature. The substrate as well as the semisynthetic derivatives were evaluated for their antibacterial activities against six strains. The results reveal that they are inactive or weakly active on the strains tested with the exception of 8-nitrobiochanin A (1a) which showed moderate activity (MIC = 62.5 μg∙mL<sup>−1</sup>) on Staphylococcus aureus ATCC 43300.
文摘Three ethylene diurea(EDU) concentrations(0,150 and 300 mg/L) were used to evaluate the negative impact of ozone(O3) on two cultivars of Trifolium repens L.cv.Vardan and Bundel grown under natural field conditions in a suburban area of Varanasi,India.Mean O3 concentrations varied from 30.3 to 46.6 μg/L during the experimental period.Higher photosynthetic pigments and ascorbic acid concentrations were noticed in both EDU-treated cultivars over non-EDU-treated ones,but a reverse trend was found for lipid peroxidation.Growth parameters and biomass also showed increments under EDU treatment of both cultivars.The ratio of variable fluorescence to maximum fluorescence increased significantly in Vardan but not in Bundel upon EDU treatment.Results revealed that EDU concentration of 300 mg/L was more effective to combat the oxidative stress as well as protecting plants from O3 injury symptoms.The test cultivar Vardan is relatively sensitive to O3,thereby can be used as a bioindicator of O3 pollution in areas having higher O3 concentrations.Results also indicated that Bundel has more efficient antioxidant defense system than Vardan and hence was more tolerant to O3 stress.
