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
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.
