Open AccessGenetic Mapping and Functional Analysis of the Tomato Bs4 Locus Governing Recognition of the Xanthomonas campestris pv. vesicatoria AvrBs4 Protein
Author(s) -
Agim Ballvora,
Michèle Pierre,
van den Ackerveken G,
Sebastián Schornack,
Ombeline Rossier,
Martin W. Ganal,
Thomas Lahaye,
Ulla Bonas
Publication year - 2001
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.2001.14.5.629
Subject(s) - biology , lycopersicon , xanthomonas campestris , locus (genetics) , genetics , population , pepper , gene , botany , horticulture , demography , sociology
Xanthomonas campestris pv. vesicatoria is the causal agent of bacterial spot disease on pepper (Capsicum spp.) and tomato (Lycopersicon spp.). Analysis of 17 different Lycopersicon accessions with avrBs4-expressing X. campestris pv. vesicatoria strains identified 15 resistant and two susceptible tomato genotypes. Genetic analysis revealed that AvrBs4 recognition in tomato is governed by a single locus, designated Bs4 (bacterial spot resistance locus no. 4). Amplified fragment length polymorphism and bulked DNA templates from resistant and susceptible plants were used to define a 2.6-cM interval containing the Bs4 locus. A standard tomato mapping population was employed to localize Bs4- linked markers on the short arm of chromosome 5. Investigation of X. campestris pv. vesicatoria hrp mutant strains revealed that AvrBs4 secretion and avirulence activity are hrp dependent. Agrobacterium-based delivery of the avrBs4 gene into tomato triggered a plant response that phenotypically resembled the hypersensitive response induced by avrBs4-expressing X. campestris pv. vesicatoria strains, suggesting symplastic perception of the avirulence protein. Mutations in the avrBs4 C-terminal nuclear localization signals (NLSs) showed that NLSs are dispensable for Bs4-mediated recognition. Our data suggest that tomato Bs4 and pepper Bs3 employ different recognition modes for detection of the highly homologous X. campestris pv. vesicatoria avirulence proteins AvrBs4 and AvrBs3.