Resynthesizing Brassica napus carrying genes for race specific and non-specific resistance to multiple races of Plasmodiophora brassicae

Citation

8. Karim MM, Yu F 2023 Resynthesizing Brassica napus carrying genes for race specific and non specific resistance to multiple races of Plasmodiophora brassicae. 16th International Rapeseed Congress, Sydney, Australia, September, 2023 (Abstract and Poster)

Résumé en langage clair

Clubroot on canola (B. napus) continues to spread on the Canadian prairies. Genetic resistance is considered the most economic method to control the disease. B. napus is an amphidiploid originating from hybridization between diploid species B. rapa and B. oleracea. B. rapa line T19 was found to carry three race specific resistance genes Rcr4, Rcr8 and Rcr9, while race non-specific QTLs Rcr_C03-1 and Rcr_C08-1 were identified in B. oleracea lines ECD11 and JL04; and additional QTLs are likely present in JL04. However, introgression of resistance from the diploids especially from B. oleracea into B. napus is more challenging compared to intraspecific cross breeding. We aimed to resynthesize B. napus lines with genes for race specific and race non-specific resistance using T19 crossed with ECD11 and JL04 . This will enable the rapid incorporation of a variety of clubroot resistance genes especially QTLs from the vegetable brassica species into canola for durable resistance. Reciprocal crosses of T19 with ECD11 and JL04 were performed and embryos from the resulting F1s were rescued through plant tissue culture methods. The resynthesized F1 plants were treated with colchicine to form amphidiploid, and self-pollination was perform to produce subsequent progenies. SNP markers linked to the genes/QTL identified from the donors were used for confirming the presence of the genes/QTLs through Kompetitive Allele Specific PCR (KASP) analysis. A total of 547 flowers were pollinated and 393 siliques were cultured with 50 F1 plants transplanted into soil after the treatment of colchicine. Eight resynthesized B. napus lines, four from T19 x ECD11 and 4 from T19 x JL04, were developed and self-pollination for the lines was performed until F6. Among the 8 lines, five produced adequate seeds for testing clubroot resistance with the isolates representing 8 races of the clubroot pathogen collected from canola fields in Western Canada. All the resynthesized lines were highly resistant to the races tested. The presence of the resistance genes/QTLs in the lines were confirmed through KASP analysis. The developed B. napus germplasm containing clubroot resistance from the A- and C- genomes is very valuable for developing canola cultivars resistant to clubroot as donors.

Résumé

Background:
Clubroot on canola (Brassica napus), caused by Plasmodiophora brassicae, continues to spread on the Canadian prairies. Genetic resistance is considered the most economic method to control the disease. B. napus is an amphidiploid originating from hybridization between diploid species B. rapa and B. oleracea. B. rapa line T19 was found to carry three race specific resistance genes Rcr4, Rcr8 and Rcr9 (Yu et al. 2017), while race non-specific QTLs Rcr_C03-1 and Rcr_C08-1 were identified in B. oleracea lines ECD11 (Karim & Yu 2023a) and JL04; and additional QTLs are likely present in JL04. However, introgression of resistance from the diploids especially from B. oleracea into B. napus is more challenging compared to intraspecific cross breeding.
Objective:
We aimed to resynthesize B. napus lines with genes for race specific and race non-specific resistance using T19 crossed with ECD11 and JL04 . This will enable the rapid incorporation of a variety of clubroot resistance genes especially QTLs from the vegetable brassica species into canola for durable resistance.
Methods:
Reciprocal crosses of T19 with ECD11 and JL04 were performed and embryos from the resulting F1s were rescued through plant tissue culture methods. The resynthesized F1 plants were treated with colchicine to form amphidiploid, and self-pollination was perform to produce subsequent progenies. SNP markers linked to the genes/QTL identified from the donors were used for confirming the presence of the genes/QTLs through Kompetitive Allele Specific PCR (KASP) analysis.

Results:
A total of 547 flowers were pollinated and 393 siliques were cultured with 50 F1 plants transplanted into soil after the treatment of colchicine. Eight resynthesized B. napus lines, four from T19 x ECD11 and 4 from T19 x JL04, were developed and self-pollination for the lines was performed until F6. Among the 8 lines, five produced adequate seeds for testing clubroot resistance with the isolates representing 8 races of P. brassicae collected from canola fields in Western Canada. All the resynthesized lines were highly resistant to the races tested. The presence of the resistance genes/QTLs in the lines were confirmed through KASP analysis.
Conclusions:
The developed B. napus germplasm containing clubroot resistance from the A- and C- genomes is very valuable for developing canola cultivars resistant to clubroot as donors.

Date de publication

2023-09-24

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