Rice blast disease caused by Magnaporthe oryzae poses a serious threat to rice security worldwide.This filamentous pathogen modulates rice defense responses by secreting effectors to facilitate infection.The phytohorm...Rice blast disease caused by Magnaporthe oryzae poses a serious threat to rice security worldwide.This filamentous pathogen modulates rice defense responses by secreting effectors to facilitate infection.The phytohormone jasmonic acid(JA)plays crucial roles in the response to rice blast fungus.However,how M.oryzae disrupts JA-mediated resistance in rice is not well understood.In this study,we identify a new effector,a chloroplast-targeting protein(MoCHT1),from M.oryzae.Knocking out MoCHT1 decreases virulence,whereas heterologous expression of MoCHT1 in rice compromises disease resistance.MoCHT1 interacts with a rice LESION AND LAMINA BENDING(OsLLB)protein,a negative regulator of JA biosynthesis in the chloroplast.Loss-of-function of Os LLB leads to increased JA accumulation,thereby improving resistance to rice blast.The interaction between MoCHT1 and OsLLB results in the inhibition of OsLLB degradation,consequently reducing JA accumulation,thereby impairing JA content and decreasing plant disease resistance.Overall,this study reveals the molecular mechanism by which M.oryzae utilizes MoCHT1 to subvert rice JA signaling,broadening our understanding of how pathogens circumvent host immune responses by manipulating plant defense hormone biosynthesis.展开更多
The transition from the vegetative phase to the reproductive phase is a major developmental process in flowering plants.The underlying mechanism controlling this cellular process remains a research focus in the field ...The transition from the vegetative phase to the reproductive phase is a major developmental process in flowering plants.The underlying mechanism controlling this cellular process remains a research focus in the field of plant molecular biology.In the present work,we identified a gene encoding the C3H2C3-type RING finger protein Nt RCP1 from tobacco BY-2 cells.Enzymatic analysis demonstrated that Nt RCP1 is a functional E3 ubiquitin ligase.In tobacco plants,expression level of Nt RCP1 was higher in the reproductive shoot apices than in the vegetative ones.Nt RCP1-overexpressing plants underwent a more rapid transition from the vegetative to the reproductive phase and flowered markedly earlier than the wild-type control.Histological analysis revealed that the shoot apical meristem of Nt RCP1-overexpressing plants initiated inflorescence primordia precociously compared to the wild-type plant due to accelerated cell division.Overexpression of Nt RCP1 in BY-2 suspension cells promoted cell division,which was a consequence of the shortened G2 phase in the cell cycle.Together,our data suggest that Nt RCP1 may act as a regulator of the phase transition,possibly through its role in cell cycle regulation,during vegetative/reproductive development in tobacco plant.展开更多
Cell elongation and secondary wall deposition are two consecutive stages during cotton fiber development. The mechanisms controlling the progression of these two developmental phases remain largely unknown. Here, we r...Cell elongation and secondary wall deposition are two consecutive stages during cotton fiber development. The mechanisms controlling the progression of these two developmental phases remain largely unknown. Here, we report the functional characterization of the actin-bundling protein GhFIM2 in cotton fiber. Overexpression of GhFIM2 increased the abundance of actin bundles, which was accompanied with accelerated fiber growth at the fastelongating stage. Meanwhile, overexpression of GhFIM2 could propel the onset of secondary cell wall biogenesis. These results indicate that the dynamic rearrangement of actin higher structures involving GhFIM2 plays an important role in the development of cotton fiber cells.展开更多
AaNhaD, a gene isolated from the soda lake alkaliphile Alkalimonas amylolytica, encodes a Na＋/H＋ antiporter crucial for the bacterium＇s resistance to salt/alkali stresses. However, it remains unknown whether this t...AaNhaD, a gene isolated from the soda lake alkaliphile Alkalimonas amylolytica, encodes a Na＋/H＋ antiporter crucial for the bacterium＇s resistance to salt/alkali stresses. However, it remains unknown whether this type of bacterial gene may be able to increase the tolerance of flowering plants to salt/alkali stresses. To investigate the use of extremophile genetic resources in higher plants, transgenic tobacco BY-2 cells and plants harboring AaNhaDwere generated and their stress tolerance was evaluated. Ectopic expression of AaNhaD enhanced the salt tolerance of the transgenic BY-2 cells in a pH-dependent manner. Compared to wild-type controls, the transgenic cells exhibited increased Na＋ concentrations and pH levels in the vacuoles. Subcellular localization analysis indicated that AaNhaD-GFP fusion proteins were primarily localized in the tonoplasts. Similar to the transgenic BY-2 cells, AaNhaD.overexpressing tobacco plants displayed enhanced stress tolerance when grown in saline-alkali soil. These results indicate that AaNhaD functions as a pH-dependent tonoplast Na＋/H＋ antiporter in plant cells, thus presenting a new avenue for the genetic improvement of salinity/alkalinity tolerance.展开更多
The dynamic assembly of the actin cytoskeleton is vital for Magnaporthe oryzae development and host infection.The actin-related protein MoFim1 is a key factor for organizing the M.oryzae actin cytoskeleton.Currently,h...The dynamic assembly of the actin cytoskeleton is vital for Magnaporthe oryzae development and host infection.The actin-related protein MoFim1 is a key factor for organizing the M.oryzae actin cytoskeleton.Currently,how MoFim1 is regulated in M.oryzae to precisely rearrange the actin cytoskeleton is unclear.In this study,we found that MoFim1 associates with the M.oryzae mitogen-activated protein(MAP)kinase Pmk1 to regulate actin assembly.MoFim1 directly interacted with Pmk1,and the phosphorylation level of MoFim1 was decreased inΔpmk1,which led to a change in the subcellular distribution of MoFim1 in the hyphae ofΔpmk1.Moreover,the actin cytoskeleton was aberrantly organized at the hyphal tip in theΔpmk1,which was similar to what was observed in theΔmofim1 during hyphal growth.Furthermore,phosphorylation analysis revealed that Pmk1 could phosphorylate MoFim1 at serine 94.Loss of phosphorylation of MoFim1 at serine 94 decreased actin bundling activity.Additionally,the expression of the site mutant of MoFim1 S94D(in which serine 94 was replaced with aspartate to mimic phosphorylation)inΔpmk1 could reverse the defects in actin organization and hyphal growth inΔpmk1.It also partially rescues the formation of appressorium failure inΔpmk1.Taken together,these findings suggest a regulatory mechanism in which Pmk1 phosphorylates MoFim1 to regulate the assembly of the actin cytoskeleton during hyphal development and pathogenesis.展开更多
基金funded by the Biological Breeding-National Science and Technology Major Projects(2023ZD04070)the National Natural Science Foundation of China(31970284,31900385)+1 种基金the Fujian Provincial Science and Technology Key Project(2022NZ030014)the Natural Science Foundation of Fujian Province,China(2023J01483,2022J01616)。
文摘Rice blast disease caused by Magnaporthe oryzae poses a serious threat to rice security worldwide.This filamentous pathogen modulates rice defense responses by secreting effectors to facilitate infection.The phytohormone jasmonic acid(JA)plays crucial roles in the response to rice blast fungus.However,how M.oryzae disrupts JA-mediated resistance in rice is not well understood.In this study,we identify a new effector,a chloroplast-targeting protein(MoCHT1),from M.oryzae.Knocking out MoCHT1 decreases virulence,whereas heterologous expression of MoCHT1 in rice compromises disease resistance.MoCHT1 interacts with a rice LESION AND LAMINA BENDING(OsLLB)protein,a negative regulator of JA biosynthesis in the chloroplast.Loss-of-function of Os LLB leads to increased JA accumulation,thereby improving resistance to rice blast.The interaction between MoCHT1 and OsLLB results in the inhibition of OsLLB degradation,consequently reducing JA accumulation,thereby impairing JA content and decreasing plant disease resistance.Overall,this study reveals the molecular mechanism by which M.oryzae utilizes MoCHT1 to subvert rice JA signaling,broadening our understanding of how pathogens circumvent host immune responses by manipulating plant defense hormone biosynthesis.
基金supported by the Natural Science Foundation of China(Grant Nos.31100870 and30800556)
文摘The transition from the vegetative phase to the reproductive phase is a major developmental process in flowering plants.The underlying mechanism controlling this cellular process remains a research focus in the field of plant molecular biology.In the present work,we identified a gene encoding the C3H2C3-type RING finger protein Nt RCP1 from tobacco BY-2 cells.Enzymatic analysis demonstrated that Nt RCP1 is a functional E3 ubiquitin ligase.In tobacco plants,expression level of Nt RCP1 was higher in the reproductive shoot apices than in the vegetative ones.Nt RCP1-overexpressing plants underwent a more rapid transition from the vegetative to the reproductive phase and flowered markedly earlier than the wild-type control.Histological analysis revealed that the shoot apical meristem of Nt RCP1-overexpressing plants initiated inflorescence primordia precociously compared to the wild-type plant due to accelerated cell division.Overexpression of Nt RCP1 in BY-2 suspension cells promoted cell division,which was a consequence of the shortened G2 phase in the cell cycle.Together,our data suggest that Nt RCP1 may act as a regulator of the phase transition,possibly through its role in cell cycle regulation,during vegetative/reproductive development in tobacco plant.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2016YFD0100505-09)the National Natural Science Foundation(31100870)the State Key Laboratory of Plant Genomics of China(2015B0129-02)
文摘Cell elongation and secondary wall deposition are two consecutive stages during cotton fiber development. The mechanisms controlling the progression of these two developmental phases remain largely unknown. Here, we report the functional characterization of the actin-bundling protein GhFIM2 in cotton fiber. Overexpression of GhFIM2 increased the abundance of actin bundles, which was accompanied with accelerated fiber growth at the fastelongating stage. Meanwhile, overexpression of GhFIM2 could propel the onset of secondary cell wall biogenesis. These results indicate that the dynamic rearrangement of actin higher structures involving GhFIM2 plays an important role in the development of cotton fiber cells.
基金supported by grants from the National Natural Science Foundation(30771162)the Ministry of Agriculture of China(2009ZX08009-096B)
文摘AaNhaD, a gene isolated from the soda lake alkaliphile Alkalimonas amylolytica, encodes a Na＋/H＋ antiporter crucial for the bacterium＇s resistance to salt/alkali stresses. However, it remains unknown whether this type of bacterial gene may be able to increase the tolerance of flowering plants to salt/alkali stresses. To investigate the use of extremophile genetic resources in higher plants, transgenic tobacco BY-2 cells and plants harboring AaNhaDwere generated and their stress tolerance was evaluated. Ectopic expression of AaNhaD enhanced the salt tolerance of the transgenic BY-2 cells in a pH-dependent manner. Compared to wild-type controls, the transgenic cells exhibited increased Na＋ concentrations and pH levels in the vacuoles. Subcellular localization analysis indicated that AaNhaD-GFP fusion proteins were primarily localized in the tonoplasts. Similar to the transgenic BY-2 cells, AaNhaD.overexpressing tobacco plants displayed enhanced stress tolerance when grown in saline-alkali soil. These results indicate that AaNhaD functions as a pH-dependent tonoplast Na＋/H＋ antiporter in plant cells, thus presenting a new avenue for the genetic improvement of salinity/alkalinity tolerance.
基金funded by the Natural Science Foundation of Fujian Province,China(2022J01616 and 2023J01483)the Distinguished Young Scientists Fund of Fujian Agriculture and Forestry University of China(xjq202121)+1 种基金the National Natural Science Foundation of China(grant numbers.31970284,31900385)the Fujian Provincial Science and Technology Key Project(2022NZ030014).
文摘The dynamic assembly of the actin cytoskeleton is vital for Magnaporthe oryzae development and host infection.The actin-related protein MoFim1 is a key factor for organizing the M.oryzae actin cytoskeleton.Currently,how MoFim1 is regulated in M.oryzae to precisely rearrange the actin cytoskeleton is unclear.In this study,we found that MoFim1 associates with the M.oryzae mitogen-activated protein(MAP)kinase Pmk1 to regulate actin assembly.MoFim1 directly interacted with Pmk1,and the phosphorylation level of MoFim1 was decreased inΔpmk1,which led to a change in the subcellular distribution of MoFim1 in the hyphae ofΔpmk1.Moreover,the actin cytoskeleton was aberrantly organized at the hyphal tip in theΔpmk1,which was similar to what was observed in theΔmofim1 during hyphal growth.Furthermore,phosphorylation analysis revealed that Pmk1 could phosphorylate MoFim1 at serine 94.Loss of phosphorylation of MoFim1 at serine 94 decreased actin bundling activity.Additionally,the expression of the site mutant of MoFim1 S94D(in which serine 94 was replaced with aspartate to mimic phosphorylation)inΔpmk1 could reverse the defects in actin organization and hyphal growth inΔpmk1.It also partially rescues the formation of appressorium failure inΔpmk1.Taken together,these findings suggest a regulatory mechanism in which Pmk1 phosphorylates MoFim1 to regulate the assembly of the actin cytoskeleton during hyphal development and pathogenesis.
