The adult plant resistance conferred by genes with an additive effect is an alternative to achieve durable resistance to leaf
rust caused by the fungus
Puccinia triticina
in wheat (
Triticum
spp.) The objective of this study was to know the response to
this disease in bread wheat genotypes that possess the partial resistance genes
Lr34,
Lr46,
Lr67 and
Lr68. The severity level
of the disease was measured in 280 wheat genotypes in three locations. The presence or absence of partial resistance genes
was determined by molecular markers for each gene in 245 wheat genotypes. The different combinations of adult plant
genes resulted in the genotypes were classified into nine groups. In 77 of these genotypes, the markers were negative for
these genes. The
Lr34,
Lr46,
Lr67 and
Lr68 genes were identified individually in 48, 48, 5, and 14 genotypes, respectively.
The combination of two genes,
Lr34+
Lr46,
Lr34+
Lr68 and
Lr46+
Lr68, was determined in 18, 17, and 12 genotypes,
respectively. Only in six genotypes the combination
Lr34+
Lr46+
Lr68 was identified. The genotypes with the
Lr34,
Lr46,
Lr67 and
Lr68 genes in a unique form showed 21%, 24.8%, 21.9% and 21.8% of rust severity on average, respectively. An
additive effect was observed in the combinations of two genes, and higher effect in the combinations that included the
Lr34
gene since genotypes with this gene combination showed on average 11.4% of rust severity. The combination of three genes
Lr34+
Lr46+
Lr68 provide greater protection in the genotypes with 9.7% of rust severity on average.
