Abscisic acid(ABA)hydroxylation is an important pathway for ABA inactivation and homeostasis maintenance.Here,we discover a new downstream catabolite of neophaseic acid(neoPA)in the ABA 90-hydroxyl pathway and identif...Abscisic acid(ABA)hydroxylation is an important pathway for ABA inactivation and homeostasis maintenance.Here,we discover a new downstream catabolite of neophaseic acid(neoPA)in the ABA 90-hydroxyl pathway and identify it as epi-neodihydrophaseic acid(epi-neoDPA)by comparing its accurate mass,retention time,and MSn spectra with those of our chemically synthesized epi-neoDPA.Analyses of Arabidopsis seed germination and ABA-related gene expression reveal that neoPA rather than epi-neoDPA possesses ABA-like hormonal activity.In vitro enzyme activity tests of prokaryotic recombinant protein reveal that NeoPAR1(neoPA reductase 1)identified from Arabidopsis converts neoPA into epi-neoDPA.Sitedirected mutation at Tyr163 in the conserved motif of NeoPAR1 abolishes the catalytic activity of NeoPAR1.Accelerated seed germination was observed in NeoPAR1 knockdown and knockout mutants,whereas retarded seed germination and the accumulation of epi-neoDPA and ABA were observed in NeoPAR1 overexpression lines,suggesting that NeoPAR1 is involved in seed germination and maintenance of ABA homeostasis.展开更多
基金This work is supported by the National Key R&D Program of China(2018YFA0900400)the National Natural Science Foundation of China(21635006,31670373,21721005).
文摘Abscisic acid(ABA)hydroxylation is an important pathway for ABA inactivation and homeostasis maintenance.Here,we discover a new downstream catabolite of neophaseic acid(neoPA)in the ABA 90-hydroxyl pathway and identify it as epi-neodihydrophaseic acid(epi-neoDPA)by comparing its accurate mass,retention time,and MSn spectra with those of our chemically synthesized epi-neoDPA.Analyses of Arabidopsis seed germination and ABA-related gene expression reveal that neoPA rather than epi-neoDPA possesses ABA-like hormonal activity.In vitro enzyme activity tests of prokaryotic recombinant protein reveal that NeoPAR1(neoPA reductase 1)identified from Arabidopsis converts neoPA into epi-neoDPA.Sitedirected mutation at Tyr163 in the conserved motif of NeoPAR1 abolishes the catalytic activity of NeoPAR1.Accelerated seed germination was observed in NeoPAR1 knockdown and knockout mutants,whereas retarded seed germination and the accumulation of epi-neoDPA and ABA were observed in NeoPAR1 overexpression lines,suggesting that NeoPAR1 is involved in seed germination and maintenance of ABA homeostasis.