Identification of Quantitative Trait Loci Contributing Partial Resistance to Canadian Isolates of <i>Aphanomyces euteiches</i> in a Pea <scp>RIL</scp> Population Derived From a New Resistance Source

ABSTRACT Aphanomyces root rot (ARR) caused by the soil‐borne oomycete pathogen Aphanomyces euteiches is an important concern for global pea production, ~30% of which is produced in western Canada. Host plant resistance is the primary option for management of ARR and sources of partial resistance have been identified. The objective of this research was to explore the genetic basis of ARR resistance in a new resistance source, No. 9292 (PI 195020), when challenged with two Canadian isolates of A. euteiches . A recombinant inbred line (RIL) population of 204 F 8:9 RILs derived from the crossing of partially resistant parent No. 9292 × CDC Amarillo was genotyped using an Axiom 90K SNP array and phenotyped under controlled environment conditions using a moderately (AE11) and highly virulent (AE13) A. euteiches isolate. Three quantitative trait loci (QTLs) from No. 9292 on LG1, LG3 and LG4 with logarithm of the odds (LOD) values of 5.6, 3.8 and 5.3 contributed to partial resistance against AE11. The QTLs on LG1 and LG4 co‐localised with known QTLs Ae‐Ps1.2 and Ae‐Ps4.1 , respectively. The QTL interval of Ae‐Ps4.1 was reduced from 15.4 to 10.1 cM. Ae‐Ps4.1 and Ae‐Ps2 . 4 contributed by No. 9292 and Ae‐Ps6.3 contributed by CDC Amarillo were also associated with partial resistance against isolate AE13. In the peak region of Ae‐Ps4.1 for AE13, a defence‐related peroxidase and WRKY DNA‐binding domain gene were identified. Results validated known and identified new QTLs that will contribute to the durability of resistance to ARR in pea cultivars.