title: Verticillium infection triggers VASCULAR-RELATED NAC DOMAIN7-dependent de novo xylem formation and enhances drought tolerance in Arabidopsis.
abstract: The soilborne fungal plant pathogen Verticillium longisporum invades the roots of its Brassicaceae hosts and proliferates in the plant vascular system. Typical aboveground symptoms of Verticillium infection on Brassica napus and Arabidopsis thaliana are stunted growth, vein clearing, and leaf chloroses. Here, we provide evidence that vein clearing is caused by pathogen-induced transdifferentiation of chloroplast-containing bundle sheath cells to functional xylem elements. In addition, our findings suggest that reinitiation of cambial activity and transdifferentiation of xylem parenchyma cells results in xylem hyperplasia within the vasculature of Arabidopsis leaves, hypocotyls, and roots. The observed de novo xylem formation correlates with Verticillium-induced expression of the VASCULAR-RELATED NAC DOMAIN (VND) transcription factor gene VND7. Transgenic Arabidopsis plants expressing the chimeric repressor VND7-SRDX under control of a Verticillium infection-responsive promoter exhibit reduced de novo xylem formation. Interestingly, infected Arabidopsis wild-type plants show higher drought stress tolerance compared with noninfected plants, whereas this effect is attenuated by suppression of VND7 activity. Together, our results suggest that V. longisporum triggers a tissue-specific developmental plant program that compensates for compromised water transport and enhances the water storage capacity of infected Brassicaceae host plants. In conclusion, we provide evidence that this natural plant-fungus pathosystem has conditionally mutualistic features.
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute, Georg-August-University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Gottingen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reusche
authors.forename: Karin
authors.initials: K
authors.lastname: Thole
authors.forename: Dennis
authors.initials: D
authors.lastname: Janz
authors.forename: Jekaterina
authors.initials: J
authors.lastname: Truskina
authors.forename: Sören
authors.initials: S
authors.lastname: Rindfleisch
authors.forename: Christine
authors.initials: C
authors.lastname: Drübert
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Volker
authors.initials: V
authors.lastname: Lipka
authors.forename: Thomas
authors.initials: T
authors.lastname: Teichmann
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D029688:Brassica napus / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D002454:Cell Differentiation; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D009928:Organ Specificity; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D058526:Plant Vascular Bundle / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020172:Verticillium / Q000502:physiology*; D014867:Water / Q000378:metabolism; D052584:Xylem / Q000166:cytology / Q000235:genetics / Q000382:microbiology / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C583237:VND7 protein, Arabidopsis; D014867:Water