Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,...Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,and whether the effects differ between native and introduced populations of invasive plants.We performed a greenhouse experiment with introduced(the USA)and native(Argentina)genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth,constitutive and herbivore(Agasicles hygrophila)-induced chemical defense,and herbivory tolerance.We measured total biomass,elongation rate(as proxy of growth rate),carbon and nitrogen,and the concentration of triterpenoid saponins(defensive chemicals)in leaves and roots.Constitutive resistance(+33%higher leaf triterpenoid saponins in control treatment at low nitrogen level)and tolerance[less decreased total biomass after herbivory treatment(−24%and−15%for high and low nitrogen levels)]were favored at lower nitrogen level,while induced resistance was favored at higher nitrogen level(+24%increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level).Constitutive resistance and tolerance exhibited trade-offs with growth rate,while induced resistance positively correlated with growth rate.Additionally,the introduced genotypes had−6%lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level,but such difference was absent at high nitrogen level.Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant,and interweave with herbivory to determine the performance of introduced genotypes.展开更多
A set of proteins and noncoding RNAs, referred to as the male specific lethal （MSL） complex, is present on the male X chromosome in Drosophila and has been postulated to be responsible for dosage compensation of thi...A set of proteins and noncoding RNAs, referred to as the male specific lethal （MSL） complex, is present on the male X chromosome in Drosophila and has been postulated to be responsible for dosage compensation of this chromosome -- the up-regulation of its expression to be equal to that of two X chromosomes in females. This hypothesis is evaluated in view of lesser known aspects of dosage compensation such as the fact that metafemales with three X chromosomes also have equal expression to normal females, which would require a down-regulation of each gene copy Moreover, when this complex is ectopically expressed in females or specifically targeted to a reporter in males, there is no increase in expression of the genes or targets with which it is associated. These observations are not consistent with the hypothesis that the MSL complex conditions dosage compensation. A synthesis is described that can account for these observations.展开更多
基金supported by the National Natural Science Foundation of China(grant no.41771053,32071659,31961133028 and 32030067).
文摘Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,and whether the effects differ between native and introduced populations of invasive plants.We performed a greenhouse experiment with introduced(the USA)and native(Argentina)genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth,constitutive and herbivore(Agasicles hygrophila)-induced chemical defense,and herbivory tolerance.We measured total biomass,elongation rate(as proxy of growth rate),carbon and nitrogen,and the concentration of triterpenoid saponins(defensive chemicals)in leaves and roots.Constitutive resistance(+33%higher leaf triterpenoid saponins in control treatment at low nitrogen level)and tolerance[less decreased total biomass after herbivory treatment(−24%and−15%for high and low nitrogen levels)]were favored at lower nitrogen level,while induced resistance was favored at higher nitrogen level(+24%increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level).Constitutive resistance and tolerance exhibited trade-offs with growth rate,while induced resistance positively correlated with growth rate.Additionally,the introduced genotypes had−6%lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level,but such difference was absent at high nitrogen level.Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant,and interweave with herbivory to determine the performance of introduced genotypes.
基金supported by the National Institutes of Health grant of the United States(No.RO1GM068042)
文摘A set of proteins and noncoding RNAs, referred to as the male specific lethal （MSL） complex, is present on the male X chromosome in Drosophila and has been postulated to be responsible for dosage compensation of this chromosome -- the up-regulation of its expression to be equal to that of two X chromosomes in females. This hypothesis is evaluated in view of lesser known aspects of dosage compensation such as the fact that metafemales with three X chromosomes also have equal expression to normal females, which would require a down-regulation of each gene copy Moreover, when this complex is ectopically expressed in females or specifically targeted to a reporter in males, there is no increase in expression of the genes or targets with which it is associated. These observations are not consistent with the hypothesis that the MSL complex conditions dosage compensation. A synthesis is described that can account for these observations.
