QTL analysis for late blight resistance in a tetraploid mapping population derived from late blight resistant ‘Palisade Russet’

Wednesday, July 28, 2021
1:25 PM - 1:45 PM

Potato late blight (causal agent Phytophthora infestans) is a devastating disease of potato worldwide, with control primarily though monitoring of the disease and application of fungicides. The development of new pathotypes of P. infestans has made the control of late blight through fungicides and host plant resistance difficult over time. In order to gain a better understanding of host plant resistance that may prove useful in the development of more durable late blight resistance in the future, QTL analysis was conducted on a tetraploid mapping population derived from the late blight resistant variety Palisade Russet. A total 190 progeny from the intercrossing of Palisade Russet with a late blight susceptible breeding clone (ND028673B-2Russ) were utilized. The two parents and progeny were evaluated over a two year period for response to infection using the US-8 genotype of P. infestans in inoculated field screenings. The raw phenotypic data for late blight response was converted to best linear unbiased prediction (BLUP), using a mixed model. The SolCAP 22K SNP chip was used for genotyping the whole mapping population. ClusterCall and MAPpoly (R-packages) were subsequently used for autotetraploid SNP calling and linkage mapping. The generated 12 chromosome linkage maps and the BLUP data were imported into QTLpoly, an R-package developed for polyploid QTL analyses. One significant QTL associated with late blight resistance was consistently detected on chromosome 5 across years, with a heritability ranging from 0.29 to 0.68.
Breeding and Genetics