TY - JOUR
T1 - Impact of initial pathogen density on resistance and tolerance in a polymorphic disease resistance gene system in Arabidopsis thaliana
AU - Roux, Fabrice
AU - Gao, Liping
AU - Bergelson, Joy
PY - 2010/5
Y1 - 2010/5
N2 - The evolution of natural enemy defense shapes evolutionary trajectories of natural populations. Although the intensity of selection imposed by enemies clearly varies among natural populations, little is known about the reaction norm of genotypes under a gradient of selective pressure. In this study, we measure the quantitative responses of disease symptoms and plant fitness to a gradient of infection, focusing on the gene-for-gene interaction between the Rpm1 resistance gene in Arabidopsis thaliana and the AvrRpm1 avirulence gene in the bacterial pathogen Pseudomonas syringae. Two complementary sets of plant material were used: resistant (R) and susceptible (S) isogenic lines and a set of six natural accessions, three of which are Rpm1 resistant (R) and three of which are rpm1 susceptible (S). Nine initial pathogen densities were applied to each plant line. Using isogenic lines allows any differences between R and S lines to be attributed directly to the Rpm1 gene, whereas using natural accessions allows the natural variation of resistance and tolerance over a gradient of infection dosages within R and S accessions to be described. For both sets of plant material, increased infection dosage results in more extensive disease symptoms, with a subsequent decrease in seed production. The severity of disease symptoms was reduced in R relative to S subgroups, and the presence of the Rpm1 allele led to an increase in plant fitness. Tolerance, defined as the ability to sustain infection without a reduction in fitness, was directly affected by Rpm1, providing a novel demonstration of an R gene affecting tolerance. Genetic variation for tolerance was also found within the S and R natural accessions, suggesting the potential for selection to act upon this important trait.
AB - The evolution of natural enemy defense shapes evolutionary trajectories of natural populations. Although the intensity of selection imposed by enemies clearly varies among natural populations, little is known about the reaction norm of genotypes under a gradient of selective pressure. In this study, we measure the quantitative responses of disease symptoms and plant fitness to a gradient of infection, focusing on the gene-for-gene interaction between the Rpm1 resistance gene in Arabidopsis thaliana and the AvrRpm1 avirulence gene in the bacterial pathogen Pseudomonas syringae. Two complementary sets of plant material were used: resistant (R) and susceptible (S) isogenic lines and a set of six natural accessions, three of which are Rpm1 resistant (R) and three of which are rpm1 susceptible (S). Nine initial pathogen densities were applied to each plant line. Using isogenic lines allows any differences between R and S lines to be attributed directly to the Rpm1 gene, whereas using natural accessions allows the natural variation of resistance and tolerance over a gradient of infection dosages within R and S accessions to be described. For both sets of plant material, increased infection dosage results in more extensive disease symptoms, with a subsequent decrease in seed production. The severity of disease symptoms was reduced in R relative to S subgroups, and the presence of the Rpm1 allele led to an increase in plant fitness. Tolerance, defined as the ability to sustain infection without a reduction in fitness, was directly affected by Rpm1, providing a novel demonstration of an R gene affecting tolerance. Genetic variation for tolerance was also found within the S and R natural accessions, suggesting the potential for selection to act upon this important trait.
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U2 - 10.1534/genetics.109.112383
DO - 10.1534/genetics.109.112383
M3 - Article
C2 - 20142437
AN - SCOPUS:77956644352
SN - 0016-6731
VL - 185
SP - 283
EP - 291
JO - Genetics
JF - Genetics
IS - 1
ER -