Open AccessCharacterization of AvrBs3-Like Effectors from a Brassicaceae Pathogen Reveals Virulence and Avirulence Activities and a Protein with a Novel Repeat Architecture
Author(s) -
Sabine Kay,
Jens Boch,
Ulla Bonas
Publication year - 2005
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi-18-0838
Subject(s) - biology , xanthomonas , effector , xanthomonas campestris , virulence , gene , genetics , nicotiana benthamiana , xanthomonas campestris pv. campestris , brassicaceae , xanthomonas citri , microbiology and biotechnology , botany , biochemistry
Xanthomonas campestris pv. armoraciae strain 5 is a Brassicaceae pathogen that expresses three members of the highly related avrBs3 gene family of type III effectors. Here, we report on the isolation and characterization of these genes, designated hax2, hax3, and hax4 (homolog of avrBs3 in Xanthomonas). All three Hax proteins are translocated from Xanthomonas spp. into the plant cell via the type III secretion system. Hax3 and Hax4 show the typical structure of AvrBs3-like effectors and contain a repetitive region in their central part consisting of 34-amino-acid (aa) repeats. By contrast, the Hax2 repeat region is composed of 35-aa repeats that are characterized by an additional proline residue. Hax2, Hax3, and Hax4 contain 21.5, 11.5, and 14.5 repeats, respectively. Genetic studies revealed an additive effect of hax2, hax3, and hax4 on disease symptom formation of X. campestris pv. armoraciae strain 5 on radish. The contribution of individual genes to the aggressiveness of strain 5 is quantitatively different, with hax2 showing the strongest effect on the development of chlorosis and necrosis. In addition, hax3 and hax4, but not hax2, have a Bs4-dependent avirulence activity in tomato and in transgenic Nicotiana benthamiana expressing the Bs4 resistance gene.