Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk...Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk of drought-induced mortality,but the relative contributions of these factors to the risk of mortality are unclear.In a study of the mortality of tree and shrub species during the extreme drought of 2019 in a savanna ecosystem in Southwest China,we assessed the relative contributions of evergreen and deciduous leaf habit,plant size,and species richness and diversity to the mortality of shrubs and trees after the 2019 extreme drought.The deciduous species had significantly lower hydraulic safety margins than the coexisting evergreen species,resulting in a higher mortality risk.Additionally,species and individuals with taller canopies tended to have deeper root systems,an advantage during extreme drought that reduced mortality risk.Notably,mortality risk was largely independent of stand species richness and diversity.Overall,leaf habit and plant height were better predictors of mortality risk than species richness and diversity.These novel insights provide a better understanding of the mechanisms driving drought-induced mortality in the ecosystems with a low canopy and weak interspecific and intraspecific competition for shared resources.Leaf habit and tree size should be incorporated into hypotheses on the mechanisms underlying drought-induced tree mortality.展开更多
Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-ol...Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-old Luoyang Hong plants to explore responses in terms of endogenous hormones,flowering quality,and the hormone-and flowering-associated gene expression.Exogenous GA3 application significantly promoted flower bud development and new branch growth,as well as improved flowering quality.Exogenous GA3 application also stimulated the synthesis of endogenous GA3 and indole-3-acetic acid(IAA)but reduced abscisic acid(ABA)levels.To further elucidate the regulatory mechanism,eight genes for GA biosynthesis and signaling,including PsCPS,PsKS,PsGA3ox,PsGA2ox,PsGID1b,PsGID1c,PsDELLA,and PsGID2 were cloned for the first time,and sequence analysis was also performed.The results suggested that all the cloned genes have conserved structure as each homologous gene reported in the other species.Phylogenetic trees constructed by the each cloned gene showed that the phylogenetic evolutionary relationship of P.suffruticosa was closely related to Vitis vinifera.The expression patterns of the above genes,and genes for ABA and IAA biosynthetic and signaling,and the flowering time were also investigated.Most of the above genes showed higher expression in the control buds than those in the GA3 treated buds at six developmental stages,whereas the expression levels of PsSOC1 and PsSPL9 were up-regulated by GA3 treatment.The results also showed that the GA-biosynthetic and signaling pathways are conserved in tree peony,and the PsCPS,PsGA3ox,PsGA2ox,PsGID1,PsDELLA,and PsGID2 genes are necessary for feedback regulation of GAs.Furthermore,hormone changes promoted PsSOC1 and PsSPL9 expression,and repressed PsSVP expression,which contributed to the improvement flowering quality in tree peony of forcing culture.展开更多
基金supported by the National Natural Science Foundation of China(31600479,32371576)the Key R&D Program of Yunnan Province(202403AC100028)+1 种基金the Youth Academic and Technical Leading Talent Reserve Program in Yunnan Province(202405AC350012)the 14th Five-Year Plans of Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences(XTBG-1450101,E3ZKFF2B01).
文摘Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk of drought-induced mortality,but the relative contributions of these factors to the risk of mortality are unclear.In a study of the mortality of tree and shrub species during the extreme drought of 2019 in a savanna ecosystem in Southwest China,we assessed the relative contributions of evergreen and deciduous leaf habit,plant size,and species richness and diversity to the mortality of shrubs and trees after the 2019 extreme drought.The deciduous species had significantly lower hydraulic safety margins than the coexisting evergreen species,resulting in a higher mortality risk.Additionally,species and individuals with taller canopies tended to have deeper root systems,an advantage during extreme drought that reduced mortality risk.Notably,mortality risk was largely independent of stand species richness and diversity.Overall,leaf habit and plant height were better predictors of mortality risk than species richness and diversity.These novel insights provide a better understanding of the mechanisms driving drought-induced mortality in the ecosystems with a low canopy and weak interspecific and intraspecific competition for shared resources.Leaf habit and tree size should be incorporated into hypotheses on the mechanisms underlying drought-induced tree mortality.
基金funded by the National Natural Science Foundation of China (31501800 and 31572156)the National Natural Science Foundation of China Youth Fund (2015QRNC001)+1 种基金the Science and Technology Cooperation Foundations of Henan Province of China (172106000005)the Agricultural Science and Technology Innovation Program (ASTIP) of the Chinese Academy of Agricultural Sciences
文摘Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-old Luoyang Hong plants to explore responses in terms of endogenous hormones,flowering quality,and the hormone-and flowering-associated gene expression.Exogenous GA3 application significantly promoted flower bud development and new branch growth,as well as improved flowering quality.Exogenous GA3 application also stimulated the synthesis of endogenous GA3 and indole-3-acetic acid(IAA)but reduced abscisic acid(ABA)levels.To further elucidate the regulatory mechanism,eight genes for GA biosynthesis and signaling,including PsCPS,PsKS,PsGA3ox,PsGA2ox,PsGID1b,PsGID1c,PsDELLA,and PsGID2 were cloned for the first time,and sequence analysis was also performed.The results suggested that all the cloned genes have conserved structure as each homologous gene reported in the other species.Phylogenetic trees constructed by the each cloned gene showed that the phylogenetic evolutionary relationship of P.suffruticosa was closely related to Vitis vinifera.The expression patterns of the above genes,and genes for ABA and IAA biosynthetic and signaling,and the flowering time were also investigated.Most of the above genes showed higher expression in the control buds than those in the GA3 treated buds at six developmental stages,whereas the expression levels of PsSOC1 and PsSPL9 were up-regulated by GA3 treatment.The results also showed that the GA-biosynthetic and signaling pathways are conserved in tree peony,and the PsCPS,PsGA3ox,PsGA2ox,PsGID1,PsDELLA,and PsGID2 genes are necessary for feedback regulation of GAs.Furthermore,hormone changes promoted PsSOC1 and PsSPL9 expression,and repressed PsSVP expression,which contributed to the improvement flowering quality in tree peony of forcing culture.
