Mapping QTL associated with partial resistance to Aphanomyces and Fusarium root rot in field pea and evaluation of Aphanomyces euteiches resistance by bulked segregant RNA-seq

• Author / Creator

  Longfei, Wu

• Root rot, caused by Aphanomyces euteiches and Fusarium spp., is an important disease of field pea (Pisum sativum) that can be managed with polygenic resistance. An F8 recombinant inbred line (RIL) population derived from the cross ‘Reward’ × ‘00-2067’ was evaluated for reaction to A. euteiches under field and greenhouse conditions. Genotyping was conducted with a 13.2K single nucleotide polymorphism (SNP) array and 222 simple sequence repeat markers. Significant genotypic effects and G×E interactions were detected in all experiments. Mapping of quantitative trait loci (QTL) identified 8 major-effect (R 2 >20%), 13 moderate-effect (10%<R2<20%) and 6 minor-effect (R2<10%) QTL. A genomic region on chromosome 4 was most consistently responsible for partial resistance to A. euteiches. To evaluate resistance to Fusarium spp., the cultivars ‘Reward’ and ‘00-02067’ were screened with Fusarium solani, F. avenaceum, F. acuminatum, F. proliferatum and F. graminearum under greenhouse conditions. Significant differences in root rot severity were found between the cultivars in response to F. avenaceum and F. graminearum, and these species were tested against the F8 RIL population. While no significant QTL were detected following inoculation with F. avenaceum, 5 QTL for root rot severity and 3 QTL each for vigor and plant height were identified for F. graminearum. The two most stable QTL for partial resistance to F. graminearum were located chromosome 4, coinciding with the region associated with partial resistance to A. euteiches. This region may be important for root rot resistance breeding and marker development. Resistance to A. euteiches was evaluated further with another RIL population derived from the cross ‘Carman’ × ‘00-2067’. Strongly resistant (R) and susceptible (S) individuals were used to construct R and S bulks, respectively, for bulked segregant RNA-seq (BSR-seq) analysis. Approximately 4.3-5.1 GB read pairs were aligned to the pea reference genome and 44,757 genes examined for expression level, 2,356 of which were differentially expressed. In total, 344.1 K SNPs were detected between the R and S bulks, with 395 variants located in 31 candidate genes. The identification of novel genes associated with partial resistance to A. euteiches may facilitate efforts to improve management of this pathogen.

• Subjects / Keywords

  • Field pea
  • root rot complex
  • Aphanomyces euteiches
  • Fusarium spp.
  • QTL mapping
  • Genetic map
  • RNA-seq

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-7r0f-c782

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.