Cytokinins(CKs)are one of the important classes of plant hormones essential for plant growth and devel-opment.TATA-box binding protein-associated factor 12b(TAF12b)is involved in CK signaling,but its molecular and bio...Cytokinins(CKs)are one of the important classes of plant hormones essential for plant growth and devel-opment.TATA-box binding protein-associated factor 12b(TAF12b)is involved in CK signaling,but its molecular and biochemical mechanisms are not fully understood.In this study,TAF12b of Nicotiana ben-thamiana(NbTAF12b)was found to mediate the CK response by directly interacting with type B response regulators(B-RRs),positive regulators of CK signaling,and inhibiting their transcriptional activities.As a transcriptional co-factor,TAF12b specifically facilitated the proteasomal degradation of non-phosphorylated B-RRs by recruiting the KISS ME DEADLY family of F-box proteins.Such interactions between TAF12b and B-RRs also occur in other plant species.Genetic transformation experiments showed that overexpression of NbTAF12b attenuates the CK-hypersensitive phenotype conferred by NbRR1 over-expression.Taken together,these results suggest a conserved mechanism in which TAF12b negatively regulates CK responses by promoting 26S proteasome-mediated B-RR degradation in multiple plant spe-cies,providing novel insights into the regulatory network of CK signaling in plants.展开更多
Geminiviruses are widespread across the globe and cause devastating diseases in food and medicinal crops.Their C3 proteins have long been known to enhance viral replication;however,the underlying molecular mechanisms ...Geminiviruses are widespread across the globe and cause devastating diseases in food and medicinal crops.Their C3 proteins have long been known to enhance viral replication;however,the underlying molecular mechanisms remain poorly understood.In this study,we show that transgenic plants overexpressing the C3 protein of tobacco curly shoot geminivirus(TbCSV)exhibit hypersensitive responses to cytokinin(CK)treatment,which largely restores the attenuated viral replication observed in the TbCSV C3 mutant(TbCSV_(mC3)).We identified NbTAF12b,a negative regulator of CK signaling in Nicotiana benthamiana,as a C3-interacting protein that attenuates TbCSV replication.TbCSV C3 not only inhibits the transcription of NbTAF12b but also competes with NbRR1 and NbKMD17 for binding to the NbTAF12b protein.This competition disrupts the formation of the NbTAF12b-NbKMD-NbRR heterotrimer and promotes NbRR1 accumulation,thereby enhancing CK signaling and ultimately facilitating TbCSV replication.C3 proteins from other distantly related geminiviruses exhibit similar 3D structures and also target NbTAF12b in vivo,suggesting that this mechanism is conserved among geminiviruses.These findings shed new light on the molecular mechanism by which TbCSV C3 facilitates viral replication through the modulation of CK signaling and provide potential molecular targets for engineering virus-resistant plants.展开更多
基金Natural Science Foundation of China(U20A2037,31972980,and 32272482)Talent Project of Zhejiang Province(2019R52033)+1 种基金Key Research and Development Program of Zhejiang Province(2019C02018)Innovation Research 2035 Pilot Plan of Southwest University(SWU-XDZD22002),China.
文摘Cytokinins(CKs)are one of the important classes of plant hormones essential for plant growth and devel-opment.TATA-box binding protein-associated factor 12b(TAF12b)is involved in CK signaling,but its molecular and biochemical mechanisms are not fully understood.In this study,TAF12b of Nicotiana ben-thamiana(NbTAF12b)was found to mediate the CK response by directly interacting with type B response regulators(B-RRs),positive regulators of CK signaling,and inhibiting their transcriptional activities.As a transcriptional co-factor,TAF12b specifically facilitated the proteasomal degradation of non-phosphorylated B-RRs by recruiting the KISS ME DEADLY family of F-box proteins.Such interactions between TAF12b and B-RRs also occur in other plant species.Genetic transformation experiments showed that overexpression of NbTAF12b attenuates the CK-hypersensitive phenotype conferred by NbRR1 over-expression.Taken together,these results suggest a conserved mechanism in which TAF12b negatively regulates CK responses by promoting 26S proteasome-mediated B-RR degradation in multiple plant spe-cies,providing novel insights into the regulatory network of CK signaling in plants.
基金financially supported by the Natural Science Foundation of China(32272482 and U20A2037)the National Key R&D Plan in China(2024YFD1400702)+2 种基金the Talent Project of Zhejiang Province(2019R52033)the Key Research and Development Program of Zhejiang Province(2019C02018)the Innovation Research 2035 Pilot Plan of Southwest University(SWU-XDZD22002).
文摘Geminiviruses are widespread across the globe and cause devastating diseases in food and medicinal crops.Their C3 proteins have long been known to enhance viral replication;however,the underlying molecular mechanisms remain poorly understood.In this study,we show that transgenic plants overexpressing the C3 protein of tobacco curly shoot geminivirus(TbCSV)exhibit hypersensitive responses to cytokinin(CK)treatment,which largely restores the attenuated viral replication observed in the TbCSV C3 mutant(TbCSV_(mC3)).We identified NbTAF12b,a negative regulator of CK signaling in Nicotiana benthamiana,as a C3-interacting protein that attenuates TbCSV replication.TbCSV C3 not only inhibits the transcription of NbTAF12b but also competes with NbRR1 and NbKMD17 for binding to the NbTAF12b protein.This competition disrupts the formation of the NbTAF12b-NbKMD-NbRR heterotrimer and promotes NbRR1 accumulation,thereby enhancing CK signaling and ultimately facilitating TbCSV replication.C3 proteins from other distantly related geminiviruses exhibit similar 3D structures and also target NbTAF12b in vivo,suggesting that this mechanism is conserved among geminiviruses.These findings shed new light on the molecular mechanism by which TbCSV C3 facilitates viral replication through the modulation of CK signaling and provide potential molecular targets for engineering virus-resistant plants.
