The phytohormone auxin,and its directional transport through tissues,plays a fundamental role in the development of higher plants.This polar auxin transport predominantly relies on PIN-FORMED(PIN)auxin exporters.Hence...The phytohormone auxin,and its directional transport through tissues,plays a fundamental role in the development of higher plants.This polar auxin transport predominantly relies on PIN-FORMED(PIN)auxin exporters.Hence,PIN polarization is crucial for development,but its evolution during the rise of morpho-logical complexity in land plants remains unclear.Here,we performed a cross-species investigation by observing the trafficking and localization of endogenous and exogenous PINs in two bryophytes,Physco-mitrium patens and Marchantia polymorpha,and in theflowering plant Arabidopsis thaliana.We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using a radioac-tive auxin export assay and by observing the phenotypic changes in transgenic bryophytes.Endogenous PINs polarize tofilamentous apices,while exogenous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes.In the Arabidopsis root epidermis,bryophytic PINs have no defined polarity.Pharmacological interference revealed a strong cytoskeletal dependence of bryophytic but not Arabidopsis PIN polarization.The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues of individual species.These results collectively reveal the divergence of PIN traf-ficking and polarity mechanisms throughout land plant evolution and the co-evolution of PIN sequence-based and cell-based polarity mechanisms.展开更多
基金supported by the European Research Council Advanced Grant (ETAP-742985 to H.T.and J.F.)by the Ministry of Science and Technology (grant 110-2636-B-005-001 to K.-J.L.).
文摘The phytohormone auxin,and its directional transport through tissues,plays a fundamental role in the development of higher plants.This polar auxin transport predominantly relies on PIN-FORMED(PIN)auxin exporters.Hence,PIN polarization is crucial for development,but its evolution during the rise of morpho-logical complexity in land plants remains unclear.Here,we performed a cross-species investigation by observing the trafficking and localization of endogenous and exogenous PINs in two bryophytes,Physco-mitrium patens and Marchantia polymorpha,and in theflowering plant Arabidopsis thaliana.We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using a radioac-tive auxin export assay and by observing the phenotypic changes in transgenic bryophytes.Endogenous PINs polarize tofilamentous apices,while exogenous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes.In the Arabidopsis root epidermis,bryophytic PINs have no defined polarity.Pharmacological interference revealed a strong cytoskeletal dependence of bryophytic but not Arabidopsis PIN polarization.The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues of individual species.These results collectively reveal the divergence of PIN traf-ficking and polarity mechanisms throughout land plant evolution and the co-evolution of PIN sequence-based and cell-based polarity mechanisms.
