Combined inoculation with dark septate endophytes(DSEs)and arbuscular mycorrhizal fungi(AMF)has been shown to promote plant growth,yet the underlying plant-fungus interaction mechanisms remain unclear.To elucidate the...Combined inoculation with dark septate endophytes(DSEs)and arbuscular mycorrhizal fungi(AMF)has been shown to promote plant growth,yet the underlying plant-fungus interaction mechanisms remain unclear.To elucidate the nature of this symbiosis,it is crucial to explore carbon(C)transport from plants to fungi and nutrient exchange between them.In this study,a pot experiment was conducted with two phosphorus(P)fertilization levels(low and normal)and four fungal inoculation treatments(no inoculation,single inoculation of AMF and DSE,and co-inoculation of AMF and DSE).The^(13)C isotope pulse labeling method was employed to quantify the plant photosynthetic C transfer from plants to different fungi,shedding light on the mechanisms of nutrient exchange between plants and fungi.Soil and mycelium δ^(13)C,soil C/N ratio,and soil C/P ratio were higher at the low P level than at the normal P level.However,soil microbial biomass C/P ratio was lower at the low P level,suggesting that the low P level was beneficial to soil C fixation and soil fungal P mineralization and transport.At the low P level,the P reward to plants from AMF and DSE increased significantly when the plants transferred the same amount of C to the fungi,and the two fungi synergistically promoted plant nutrient uptake and growth.At the normal P level,the root P content was significantly higher in the AMF-inoculated plants than in the DSE-inoculated plants,indicating that AMF contributed more than DSE to plant P uptake with the same amount of C received.Moreover,plants preferentially allocated more C to AMF.These findings indicate the presence of a source-sink balance between plant C allocation and fungal P contribution.Overall,AMF and DSE conferred a higher reward to plants at the low P level through functional synergistic strategies.展开更多
Botrytis cinerea is one of the most destructive phytopathogenic fungi,causing significant losses to horticultural crops.As a necrotrophic fungus,B.cinerea obtains nutrients by killing host cells.Secreted cell death-in...Botrytis cinerea is one of the most destructive phytopathogenic fungi,causing significant losses to horticultural crops.As a necrotrophic fungus,B.cinerea obtains nutrients by killing host cells.Secreted cell death-inducing proteins(CDIPs)play a crucial role in necrotrophic infection;however,only a limited number have been reported.For highthroughput CDIP screening,we optimized the prokaryotic expression system and compared its efficiency with other commonly used protein expression systems.The optimized prokaryotic expression system showed superior effectiveness and efficiency and was selected for subsequent CDIP screening.The screening system verified fifty-five candidate proteins and identified two novel SGNH family CDIPs:BcRAE and BcFAT.BcRAE and BcFAT exhibited high expres-sion levels throughout the infection process.Site-directed mutagenesis targeting conserved Ser residues abolished the cell death-inducing activity of both BcRAE and BcFAT.Moreover,the transient expression of BcRAE and BcFAT in plants enhanced plant resistance against B.cinerea without inducing cell death,independent of their enzymatic activities.Our results suggest a high-efficiency screening system for high-throughput CDIP screening and provide new targets for further study of B.cinerea-plant interactions.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFF 1303303)the National Natural Science Foundation of China(No.52394194).
文摘Combined inoculation with dark septate endophytes(DSEs)and arbuscular mycorrhizal fungi(AMF)has been shown to promote plant growth,yet the underlying plant-fungus interaction mechanisms remain unclear.To elucidate the nature of this symbiosis,it is crucial to explore carbon(C)transport from plants to fungi and nutrient exchange between them.In this study,a pot experiment was conducted with two phosphorus(P)fertilization levels(low and normal)and four fungal inoculation treatments(no inoculation,single inoculation of AMF and DSE,and co-inoculation of AMF and DSE).The^(13)C isotope pulse labeling method was employed to quantify the plant photosynthetic C transfer from plants to different fungi,shedding light on the mechanisms of nutrient exchange between plants and fungi.Soil and mycelium δ^(13)C,soil C/N ratio,and soil C/P ratio were higher at the low P level than at the normal P level.However,soil microbial biomass C/P ratio was lower at the low P level,suggesting that the low P level was beneficial to soil C fixation and soil fungal P mineralization and transport.At the low P level,the P reward to plants from AMF and DSE increased significantly when the plants transferred the same amount of C to the fungi,and the two fungi synergistically promoted plant nutrient uptake and growth.At the normal P level,the root P content was significantly higher in the AMF-inoculated plants than in the DSE-inoculated plants,indicating that AMF contributed more than DSE to plant P uptake with the same amount of C received.Moreover,plants preferentially allocated more C to AMF.These findings indicate the presence of a source-sink balance between plant C allocation and fungal P contribution.Overall,AMF and DSE conferred a higher reward to plants at the low P level through functional synergistic strategies.
基金supported by the National Natural Science Foundation of China(31930086,U23A20264,31972475)the National Key R&D Program of China(2021YFD2100505).
文摘Botrytis cinerea is one of the most destructive phytopathogenic fungi,causing significant losses to horticultural crops.As a necrotrophic fungus,B.cinerea obtains nutrients by killing host cells.Secreted cell death-inducing proteins(CDIPs)play a crucial role in necrotrophic infection;however,only a limited number have been reported.For highthroughput CDIP screening,we optimized the prokaryotic expression system and compared its efficiency with other commonly used protein expression systems.The optimized prokaryotic expression system showed superior effectiveness and efficiency and was selected for subsequent CDIP screening.The screening system verified fifty-five candidate proteins and identified two novel SGNH family CDIPs:BcRAE and BcFAT.BcRAE and BcFAT exhibited high expres-sion levels throughout the infection process.Site-directed mutagenesis targeting conserved Ser residues abolished the cell death-inducing activity of both BcRAE and BcFAT.Moreover,the transient expression of BcRAE and BcFAT in plants enhanced plant resistance against B.cinerea without inducing cell death,independent of their enzymatic activities.Our results suggest a high-efficiency screening system for high-throughput CDIP screening and provide new targets for further study of B.cinerea-plant interactions.
