Characterization of two recessive genes controlling resistance to all races of bacterial spot in peppers.
Bacterial spot, one of the most damaging diseases of pepper, is caused by Xanthomonas euvesicatoria. This pathogen has worldwide distribution and it is particularly devastating in tropical and sub-tropical regions where high temperatures and frequent precipitation provide ideal conditions for disease development. Three dominant resistance genes have been deployed singly and in combination in commercial cultivars, but have been rendered ineffectual by the high mutation rate or deletion of the corresponding cognate effector genes. These genes are missing in race P6, and their absence makes this race virulent on all commercial pepper cultivars. The breeding line ECW12346 is the only source of resistance to race P6 in Capsicum annuum, and displays a non-hypersensitive type of resistance. Characterization of this resistance has identified two recessive genes: bs5 and bs6. Individual analysis of these genes revealed that bs5 confers a greater level of resistance than bs6 at 25 degrees C, but in combination they confer full resistance to P6 indicating at least additive gene action. Tests carried out at 30 degrees C showed that both resistances are compromised to a significant extent, but in combination they provide almost full resistance to race P6 indicating a positive epistatic interaction at high temperatures. A scan of the pepper genome with restriction fragment length polymorphism and AFLP markers led to the identification of a set of AFLP markers for bs5. Allele-specific primers for a PCR-based bs5-marker have been developed to facilitate the genetic manipulation of this gene.
Vallejos
C Eduardo
CE
Department of Horticultural Sciences, University of Florida, Gainesville, FL 32611, USA. vallejos@ufl.edu
Jones
Valerie
V
Stall
Robert E
RE
Jones
Jeffrey B
JB
Minsavage
Gerald V
GV
Schultz
Diana C
DC
Rodrigues
Rosana
R
Olsen
Lisa E
LE
Mazourek
Michael
M
D054458:Amplified Fragment Length Polymorphism Analysis; D001483:Base Sequence; D002212:Capsicum / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D017343:Genes, Plant; D005808:Genes, Recessive; D008040:Genetic Linkage; D005819:Genetic Markers; D007113:Immunity, Innate / Q000235:genetics*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D011110:Polymorphism, Genetic; D014974:Xanthomonas / Q000276:immunology / Q000472:pathogenicity*
D005819:Genetic Markers