Canadian Forest Service Publications
Development and application of marker-assisted selection (MAS) tools for breeding of western white pine (Pinus monticola Douglas ex D. Don) resistance to blister rust (Cronartium ribicola J.C. Fisch.) in British Columbia. 2019. Liu, J-J., Fernandes, H., Zamany, A., Sikorski, M., Jaskolski, M., Sniezko, R.A. Can. J. Plant Pathol.
Issued by: Pacific Forestry Centre
Catalog ID: 39943
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Cronartium ribicola causes white pine blister rust (WPBR) on five-needle pines worldwide. After accidental introduction into North America about 100 years ago, this invasive fungus has caused heavy mortality in western white pine (Pinus monticola) and other related five-needle pines across North America. Breeding by selection of rare resistant trees is time-consuming; therefore, genomics-based tools are highly desirable to speed up the breeding process. Our laboratory previously constructed genetic maps for the P. monticola Cr2 locus that confers major gene resistance (MGR) to WPBR and identified several nucleotide-binding site leucine-rich repeat (NBS-LRR) genes as Cr2 positional candidates. In the present study, single nucleotide polymorphism (SNP) loci within Cr2 candidate genes (contig58688 and contig41490) were selected to develop qPCR-based genotyping assays using two SNP genotyping technologies (TaqMan and Kompetitive Allele Specific PCR-KASP). To evaluate the utility and efficiency of these marker-assisted selection (MAS) tools in British Columbia’s (BC’s) breeding program, we analyzed 46 open-pollinated bulk seedlots that were randomly selected across BC’s landscape. SNP genotyping results were highly consistent, with matching rates of over 99% between TaqMan and KASP assays for each specific SNP locus. The Cr2-linked alleles were absent in all genotyped samples for the snp58688-82Y locus and about 86% of all genotyped samples for the snp41490-1778M locus. These results demonstrate that both the TaqMan and KASP SNP genotyping assays are powerful MAS tools with accuracy up to 100% for prediction of Cr2-resistance in wild parental trees, as well as for resistance selection among their progeny following cross-pollination with MGR trees across BC’s landscape.
Plain Language Summary
It is very important to understand genetic factors contributing to host quantitative resistance for breeding selection of plants with enhanced resistance against pests and pathogens. Fungal pathogen (Cronartium ribicola) causes white pine blister rust (WPBR) in various native species of five-needle pines in North America. In order to reveal biological functions the pathogenesis-related (PR) proteins play during tree defense in response to WPBR infection, we profiled family organization of western white pine PR10 genes (PmPR10s) and characterized expression of the family members. We found that one PR10 gene (PmPR10-3.1) was transcriptionally upregulated in both needles and stems after rust infection using RNA-seq data. We then selected this gene for an association study, and discovered that DNA variations of PmPR10-3.1 significantly contributed to phenotypic variations of resistance related traits among 18 seed families. Furthermore, we produced and purified the PmPR10-3.1 protein in bacterial cells. The pure PmPR10-3.1 protein inhibited spore germination and hyphal growth of different fungal pathogens. Functional verification of PmPR10-3.1’s role in genetic resistance to WPBR provided a biomarker for long-term management of WPBR in western white pine and other related native species in North America.