Control of plant defense mechanisms and fire blight pathogenesis through the regulation of 6-thioguanine biosynthesis in Erwinia amylovora.
Fire blight is a devastating disease of Rosaceae plants, such as apple and pear trees. It is characterized by necrosis of plant tissue, caused by the phytopathogenic bacterium Erwinia amylovora. The plant pathogen produces the well-known antimetabolite 6-thioguanine (6TG), which plays a key role in fire blight pathogenesis. Here we report that YcfR, a member of the LTTR family, is a major regulator of 6TG biosynthesis in E. amylovora. Inactivation of the regulator gene (ycfR) led to dramatically decreased 6TG production. Infection assays with apple plants (Malus domestica cultivar Holsteiner Cox) and cell cultures of Sorbus aucuparia (mountain ash, rowan) revealed abortive fire blight pathogenesis and reduced plant response (biphenyl and dibenzofuran phytoalexin production). In the presence of the ΔycfR mutant, apple trees were capable of activating the abscission machinery to remove infected tissue. In addition to unveiling the regulation of 6TG biosynthesis in a major plant pathogen, we demonstrate for the first time that this antimetabolite plays a pivotal role in dysregulating the plant response to infection.
Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology, HKI, Beutenbergstrasse 11a, 07745 Jena (Germany).
Sébastien
S
Coyne
Agnieszka
A
Litomska
Cornelia
C
Chizzali
Mohammed N A
MN
Khalil
Klaus
K
Richter
Ludger
L
Beerhues
Christian
C
Hertweck
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001572:Benzofurans / Q000737:chemistry / Q000378:metabolism; D001713:Biphenyl Compounds / Q000737:chemistry / Q000378:metabolism; D044084:Erwinia amylovora / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D059828:Plant Cells / Q000737:chemistry / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D027824:Rosaceae / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism; D013866:Thioguanine / Q000737:chemistry / Q000378:metabolism*; D000094162:Phytoalexins
D001425:Bacterial Outer Membrane Proteins; D001572:Benzofurans; D001713:Biphenyl Compounds; D012717:Sesquiterpenes; D013866:Thioguanine; D000094162:Phytoalexins; C010574:biphenyl; C023614:dibenzofuran
abscission; biological activity; gene regulation; plant pathogens; sulfur compounds