The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal （AM） fungi from the phylum Glomeromycota. This mutualistic symbiosis provid...The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal （AM） fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal trans- porters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise func- tions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT ham- pers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phos- phate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A146 （in transmembrane domain [TNID] IV） and Va1357 （in TMD VIII） of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results pro- vide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita.展开更多
Nitrate-induced Ca^(2+) signaling is crucial for the primary nitrate response in plants.However,the molecular mechanism underlying the generation of the nitrate-specific calcium signature remains unknown.We report her...Nitrate-induced Ca^(2+) signaling is crucial for the primary nitrate response in plants.However,the molecular mechanism underlying the generation of the nitrate-specific calcium signature remains unknown.We report here that a cyclic nucleotide-gated channel(CNGC)protein,CNGC15,and the nitrate transceptor(NRT1.1)constitute a molecular switch that controls calcium influx depending on nitrate levels.The expression of CNGC15 is induced by nitrate,and its protein is localized at the plasma membrane after establishment of young seedlings.We found that disruption of CNGC15 results in the loss of the nitrate-induced Ca^(2+) signature(primary nitrate response)and retards root growth,reminiscent of the phenotype observed in the nrt1.1 mutant.We further showed that CNGC15 is an active Ca^(2+)-permeable channel that physically interacts with the NRT1.1 protein in the plasma membrane.Importantly,we discovered that CNGC15-NRT1.1 interaction silences the channel activity of the heterocomplex,which dissociates upon a rise in nitrate levels,leading to reactivation of the CNGC15 channel.The dynamic interactions between CNGC15 and NRT1.1 therefore control the channel activity and Ca^(2+) influx in a nitrate-dependent manner.Our study reveals a new nutrient-sensing mechanism that utilizes a nutrient transceptor-channel complex assembly to couple nutrient status to a specific Ca^(2+) signature.展开更多
文摘The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal （AM） fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal trans- porters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise func- tions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT ham- pers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phos- phate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A146 （in transmembrane domain [TNID] IV） and Va1357 （in TMD VIII） of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results pro- vide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita.
基金supported by grants from the Key Program of the National Natural Science Foundation of China(31930010 to L.L.)the General Program of National Natural Science Foundation of China(no.31872170 to L.L.and no.31900234 to C.H.)+2 种基金the National Key Research and Development Program of China(YFD0300102-3 to L.L.)the Capacity Building for Sci-Tech Innovation-Fundamental Scientific Research Funds(19530050165 to L.L.).supported,in part,by a grant from the National Science Foundation(MCB-1714795 to S.L.).
文摘Nitrate-induced Ca^(2+) signaling is crucial for the primary nitrate response in plants.However,the molecular mechanism underlying the generation of the nitrate-specific calcium signature remains unknown.We report here that a cyclic nucleotide-gated channel(CNGC)protein,CNGC15,and the nitrate transceptor(NRT1.1)constitute a molecular switch that controls calcium influx depending on nitrate levels.The expression of CNGC15 is induced by nitrate,and its protein is localized at the plasma membrane after establishment of young seedlings.We found that disruption of CNGC15 results in the loss of the nitrate-induced Ca^(2+) signature(primary nitrate response)and retards root growth,reminiscent of the phenotype observed in the nrt1.1 mutant.We further showed that CNGC15 is an active Ca^(2+)-permeable channel that physically interacts with the NRT1.1 protein in the plasma membrane.Importantly,we discovered that CNGC15-NRT1.1 interaction silences the channel activity of the heterocomplex,which dissociates upon a rise in nitrate levels,leading to reactivation of the CNGC15 channel.The dynamic interactions between CNGC15 and NRT1.1 therefore control the channel activity and Ca^(2+) influx in a nitrate-dependent manner.Our study reveals a new nutrient-sensing mechanism that utilizes a nutrient transceptor-channel complex assembly to couple nutrient status to a specific Ca^(2+) signature.
