Growth-and health-promoting bacteria can boost crop productivity in a sustainable way.Pseudomonas simiae WCS417is sucha bacterium that efficiently colonizes roots,modifiesthe architecture of the root systemto increase...Growth-and health-promoting bacteria can boost crop productivity in a sustainable way.Pseudomonas simiae WCS417is sucha bacterium that efficiently colonizes roots,modifiesthe architecture of the root systemto increase its size,and induces systemic resistance to make plants more resistant to pests and pathogens.Our previous work suggested that WCS417-induced phenotypes are controlled by root cell-type-specific mechanisms.However,it remains unclear how WCS417 affects these mechanisms.In this study,we transcriptionally profiled five Arabidopsis thaliana root cell types following WCS417 colonization.We found that the cortex and endodermis have the most differentially expressed genes,even though they are not in direct contact with this epiphytic bacterium.Many of these genes are associated with reduced cell wall biogenesis,and mutant analysis suggests that this downregulation facilitates WCS417-driven root architectural changes.Furthermore,we observed elevated expression of suberin biosynthesis genes and increased deposition of suberin in the endodermis of WCS417-colonized roots.Using an endodermal barrier mutant,we showed the importance of endodermal barrier integrity for optimal plant-beneficial bacterium association.Comparison of the transcriptome profiles in the two epidermal cell types that are in direct contact with WcS417-trichoblasts that form root hairs and atrichoblasts that do not-implies a difference in potential for defense gene activation.While both cell types respond to WCS417,trichoblasts displayed both higher basal and WCS417-dependent activation of defense-related genes compared with atrichoblasts.This suggests that root hairs may activate root immunity,a hypothesis that is supported by differential immune responses in root hair mutants.Taken together,these results highlight the strength of cell-type-specific transcriptional profiling to uncover"masked"biological mechanisms underlying beneficial plant-microbe associations.展开更多
基金the Netherlands Organization of Scientific Research through ALW Topsector Grant no.831.14.001(E.H.V.)a postdoctoral fellowship from the Jane Coffin Childs Memorial Fund for Medical Research(L.M.L.)+8 种基金the NIH(5R01-GM-043778),the NSF(MCB-06-18304),the Gordon and Betty Moore Foundation and the Howard Hughes Medical Institute(P.N.B.)a postdoctoral fellowship from the Research Foundation Flanders(FWO 12B8116N)(R.d.J.)the NWO Green II Grant no.ALWGR.2017.002(R.d.J.)the Novo Nordisk Foundation Grant no.NNF19SA0059362(R.d.J.)the China Scholarship Council(CSC)scholarship no.201908320054(J.Z.)scholarship no.202006990074(J.Y.)the Technology Foundation Perspective Program Back2Roots grant no.14219(C.M.J.P.)the ERC Advanced Grant no.269072 of the European Research Council(C.M.J.P.)the NWO Gravitation Grant no.024.004.014(1.A.S.and C.M.J.).
文摘Growth-and health-promoting bacteria can boost crop productivity in a sustainable way.Pseudomonas simiae WCS417is sucha bacterium that efficiently colonizes roots,modifiesthe architecture of the root systemto increase its size,and induces systemic resistance to make plants more resistant to pests and pathogens.Our previous work suggested that WCS417-induced phenotypes are controlled by root cell-type-specific mechanisms.However,it remains unclear how WCS417 affects these mechanisms.In this study,we transcriptionally profiled five Arabidopsis thaliana root cell types following WCS417 colonization.We found that the cortex and endodermis have the most differentially expressed genes,even though they are not in direct contact with this epiphytic bacterium.Many of these genes are associated with reduced cell wall biogenesis,and mutant analysis suggests that this downregulation facilitates WCS417-driven root architectural changes.Furthermore,we observed elevated expression of suberin biosynthesis genes and increased deposition of suberin in the endodermis of WCS417-colonized roots.Using an endodermal barrier mutant,we showed the importance of endodermal barrier integrity for optimal plant-beneficial bacterium association.Comparison of the transcriptome profiles in the two epidermal cell types that are in direct contact with WcS417-trichoblasts that form root hairs and atrichoblasts that do not-implies a difference in potential for defense gene activation.While both cell types respond to WCS417,trichoblasts displayed both higher basal and WCS417-dependent activation of defense-related genes compared with atrichoblasts.This suggests that root hairs may activate root immunity,a hypothesis that is supported by differential immune responses in root hair mutants.Taken together,these results highlight the strength of cell-type-specific transcriptional profiling to uncover"masked"biological mechanisms underlying beneficial plant-microbe associations.
