Paolo M.TriozziLuca BrunelloGiacomo NoviGianmarco Ferri...
377-394页
查看更多>>摘要：Oxygen is essential for plant growth and development.Hypoxia occurs in plants due to limited oxygen avail-ability following adverse environmental conditions as well in hypoxic niches in otherwise normoxic environ-ments.However,the existence and functional integration of spatiotemporal oxygen dynamics with plant development remains unknown.In animal systems dynamic fluctuations in oxygen availability are known as cyclic hypoxia.In this study,we demonstrate that cyclic fluctuations in internal oxygen levels occur in young emerging leaves of Arabidopsis plants.Cyclic hypoxia in plants is based on a mechanism requiring the ETHYLENE RESPONSE FACTORS type Ⅶ(ERFⅦ)that are central components of the oxygen-sensing machinery in plants.The ERFⅦ-dependent mechanism allows precise adjustment of leaf growth in response to carbon status and oxygen availability within plant cells.This study thus establishes a functional connection between internal spatiotemporal oxygen dynamics and developmental processes of plants.
Dohee KooHong Gil LeeSoon Hyung BaeKyounghee Lee...
395-408页
查看更多>>摘要：Plants are aerobic organisms that rely on molecular oxygen for respiratory energy production.Hypoxic conditions,with oxygen levels ranging between 1％and 5％,usually limit aerobic respiration and affect plant growth and development.Here,we demonstrate that the hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regener-ation competence of the callus in Arabidopsis thaliana.We showed that hypoxia-repressed plant regener-ation is mediated by the RELATED TO APETALA 2.12(RAP2.12)protein,a member of the Ethylene Response Factor Ⅶ(ERF-Ⅶ)family.We found that the hypoxia-activated RAP2.12 protein promotes salicylic acid(SA)biosynthesis and defense responses,thereby inhibiting pluripotency acquisition and de novo shoot regeneration in calli.Molecular and genetic analyses revealed that RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT2(SID2)gene promoter and activate SA biosynthesis,repressing plant regeneration possibly via a PLETHORA(PLT)-dependent pathway.Consistently,the rap2.12 mutant calli exhibits enhanced shoot regeneration,which is impaired by SA treatment.Taken together,these find-ings uncover that the cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12-SID2 module.
查看更多>>摘要：Plant high-affinity K+transporters(HKTs)mediate Na+and K+uptake,maintain Na+/K+homeostasis,and therefore play crucial roles in plant salt tolerance.In this study,we present cryoelectron microscopy structures of HKTs from two classes,class I HKT1;1 from Arabidopsis thaliana(AtHKT1;1)and class Ⅱ HKT2;1 from Triticum aestivum(TaHKT2;1),in both Na+-and K+-bound states at 2.6-to 3.0-Å resolutions.Both AtHKT1;1 and TaHKT2;1 function as homodimers.Each HKT subunit consists of four tan-dem domain units(D1-D4)with a repeated K+-channel-like M-P-M topology.In each subunit,D1-D4 assemble into an ion conduction pore with a pseudo-four-fold symmetry.Although both TaHKT2;1 and AtHKT1;1 have only one putative Na+ion bound in the selectivity filter with a similar coordination pattern,the two HKTs display different K+binding modes in the filter.TaHKT2;1 has three K+ions bound in the selec-tivity filter,but AtHKT1;1 has only two K+ions bound in the filter,which has a narrowed external entrance due to the presence of a Ser residue in the first filter motif.These structures,along with compu-tational,mutational,and electrophysiological analyses,enable us to pinpoint key residues that are critical for the ion selectivity of HKTs.The findings provide new insights into the ion selectivity and ion transport mechanisms of plant HKTs and improve our understanding about how HKTs mediate plant salt tolerance and enhance crop growth.
查看更多>>摘要：Nicotiana tabacum and Nicotiana benthamiana are widely used models in plant biology research.However,genomic studies of these species have lagged.Here we report the chromosome-level reference genome assemblies for N.benthamiana and N.tabacum with an estimated 99.5％and 99.8％completeness,respec-tively.Sensitive transcription start and termination site sequencing methods were developed and used for accurate gene annotation in N.tabacum.Comparative analyses revealed evidence for the parental origins and chromosome structural changes,leading to hybrid genome formation of each species.Interestingly,the antiviral silencing genes RDR1,RDR6,DCL2,DCL3,and AGO2 were lost from one or both subgenomes in N.benthamiana,while both homeologs were kept in N.tabacum.Furthermore,the N.benthamiana genome encodes fewer immune receptors and signaling components than that of N.tabacum.These find-ings uncover possible reasons underlying the hypersusceptible nature of N.benthamiana.We developed the user-friendly Nicomics(http://lifenglab.hzau.edu.cn/Nicomics/)web server to facilitate better use of Nicotiana genomic resources as well as gene structure and expression analyses.
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