British Columbia regional meeting, 2021/Réunion régionale de la Colombie-Britannique, 2021

s / Résumés British Columbia regional meeting, 2021/Réunion régionale de la Colombie-Britannique, 2021 Dissecting the mechanisms underlying the complex plant–Ralstonia--environment interactions. N. AOUN, L. TAULEIGNE, F. LONJON, H. DESAINT, L. BOYRIE, M. BONHOMME, L. DESLANDES, F. VAILLEAU, F. ROUX, R. BERTHOME AND T. LOWEPOWER. (N. A., T.L.) Department of Plant Pathology, University of California Davis, One Shields Avenue, Davis, CA 95616851, USA; (N.A., L.T., F.L., L.D., F.V., F.R., R.B.) Laboratory of Plant-Microorganisms-Environment Interactions, National Research Institute for Agriculture, Food and Environment, French National Centre for Scientific Research, 31320 Castanet-Tolosan France; (H.D.) SYNGENTA seeds, 84260 Sarrians France; and (L.B., M. B.) Plant Science Research Laboratory, French National Centre for Scientific Research, Paul Sabatier University, 31320 Castanet-Tolosan, France The central concept of ‘disease triangle’ in plant pathology highlights the importance of environment– host–pathogen interaction for disease severity. Warmer temperatures have been shown to inhibit most of the known resistance mechanisms in plants. However, the underlying molecular mechanisms remain poorly understood. In this talk, I will unify my PhD research and planned postdoctoral research around the Ralstonia wilt disease triangle. Ralstonia are a major threat to food security around the world. During my PhD (LIPME/ INRAE-France), we dissected mechanisms underlying the interaction of temperature and plant natural variation in Ralstonia disease outcome. By exploiting the natural genetic variation in Arabidopsis thaliana, we identified and characterized the genetic basis of resistance mechanisms remaining effective at elevated temperatures. Using genome wide association (GWA) approaches on two collections of A. thaliana, we uncovered quantitative trait loci associated with natural variation of Ralstonia disease outcome. GWA analysis revealed a polygenic architecture underlying disease symptom progression that is different between both collections. We functionally validated three genes involved in plant defence responses to R. solanacearum. However, the disease triangle of bacterial wilt could not be complete without understanding how genetic variation of the pathogen affects disease outcome. My current postdoc project aims to explore the molecular mechanisms promoting fitness of diverse Ralstonia species across different tomato cultivars and across different plant species. By adopting a random barcoded transposon mutant sequencing (RB-TnSeq), I aim to identify the genetic requirements of bacterial fitness in planta. Deciphering the plant–host environment interactions is fundamental to provide solutions for crop improvement. Race typing of Puccinia striiformis f. sp. tritici in western Canada. R. BAMRAH, K. LOU, M. ABBASI, H. R. KUTCHER AND G. S. BRAR. Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; and (K.L., H.R.K.) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada Stripe rust, caused by an obligate biotrophic fungus Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat in Canada and globally. Southern British Columbia (BC) (similar geographical region as Pacific Northwest) is one of the hot-spots for stripe rust in North America. Stripe rust inoculum can easily spread across hundreds of kilometres with wind and western Canada receives part of the inoculum from Pacific Northwest. The goal of our research is to characterize race structure of the pathogen from BC as well as other provinces in western Canada. We used singlegene differential lines in ‘Avocet’ background carrying 18 known Yr genes to characterize 22 isolates. A total of 11 races were detected from 22 isolates, race C-39 (previously reported from Alberta), being the most common (represented by 45% of the isolates). Genes Yr6, Yr7, Yr8, Yr9, and YrExp2 were not effective to any race and Can. J. Plant Pathol., 2023 Vol. 45, No. 1, 1–5, https://doi.org/10.1080/07060661.2022.2102280 © 2022 The Canadian Phytopathological Society are completely defeated. Genes Yr1, Yr5, Yr15, YrSP, and Yr76 were effective against all the races. Characterization of cryptic species of Botrytis associated with fruit rot of highbush blueberry and raspberry in the Fraser Valley of British Columbia. E. C. L. BETZ, R. R. BURLAKOTI, A. NOVINSCAK AND S. SABARATNAM. Agassiz Research and Development Centre, Agriculture and Agri-Food Canada, 6947 Hwy 7, Agassiz, BC V0M 1A0, Canada; and (S.S.) Abbotsford Agriculture Centre, Ministry of Agriculture, Food & Fisheries, 1767 Angus Campbell Road, Abbotsford, BC V3G 2Y4, Canada Botrytis cinerea (Pers.) is a necrotrophic plant pathogen infecting over 200 plant species worldwide. The pathogen primarily causes fruit rot in several crops including highbush blueberry and red raspberry. To understand the species composition and genetic diversity of Botrytis population from highbush blueberry and raspberry in the Fraser Valley of British Columbia, a total of 254 isolates of Botrytis (105 from raspberry and 147 from blueberry) collected from commercial highbush blueberry and raspberry farms in 2016 were characterized using PCR-based assays. These assays were used to identify the species and mating types of Botrytis. The isolates were further differentiated based on transposable elements (TEs) in B. cinerea species complex such as ‘boty’, ‘flipper’, ‘transposa’, and ‘vacuma’. Among the Botrytis isolates from the raspberry, 99 isolates were B. cinerea and 4 were B. caroliniana X.P. Li & G. Schnabel. All the blueberry isolates were confirmed as B. cinerea. Regardless of the host, the majority of B. cinerea isolates were ‘boty’ type (~52 to 53%) followed by ‘vacuma’ (35 to 37%). The frequency of TEs type and mating types varied among cultivars and locations. Quantifying host range in the Ralstonia solanacearum IIB-4 clade. J. D. BEUTLER, D. J. NORMAN AND T. M. LOWE-POWER. (J.D.B., T.M.L.-P.) University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; (J.D.B.) The University of British Columbia, Crop Pathology and Genetics Lab, 214 Macmillan Building, 2357 Main Mall, Vancouver, BC V6T 1Z4,Canada; and (D.J.N.) UF/IFAS Extension, Mid-Florida Research and Education Center, Apopka, FL 32703, USA Bacterial wilt diseases caused by Ralstonia solanacearum are important global crop production constraints. Genetic analyses indicate the plant pathogenic species complex comprises four divergent branches (phylotypes) native to Africa, Asia, the Americas, and the South Pacific. The species complex has a remarkably broad host range, infecting over 450 plant species, but the breadth of host range is not uniform among the thousands of known strains. The phylotype IIB, sequevar 4 (IIB-4) clade exhibits a particularly broad host range and has caused multiple economically important wilt outbreaks in the Americas. Using stem inoculations of 19 non-clonal strains on diverse plant hosts, we quantified virulence and a snapshot of the host range in the IIB-4 clade. The strains were isolated from five host species in Florida, the Caribbean, and Latin Americaencompassing a broad swath of the phylotype II ancestral range. DNA sequence analysis of 49 conserved R. solanacearum genes reveals the 19 strains we phenotyped cluster into five phylogenetic subclades. Seventeen strains were highly virulent on tomato, completely wilting plants within five days. Two strains were moderately virulent, wilting a majority of leaflets within 14 days. Banana plants were broadly resistant, with only three strains exhibiting high or moderate virulence, and 11 strains showing complete avirulence. Virulence on melon and impatiens was more variable. Despite a high degree of genetic similarity, we find that R. solanacearum strains in the IIB-4 clade exhibit considerable variation in their virulence on diverse hosts and present desirable targets for genomic screening to identify the genetic determinants of host specificity. Summoning the ancestors: using an Aegilops tauschii diversity panel to improve stripe rust resistance in wheat. V. FETTERLEY, D. GILBERT, S. ARORA AND G. S. BRAR. Faculty of Land and Food Systems, The University of British Columbia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada; and (D.G., S.A.) John Innes Center, Norwich Research Park, Colney Ln, Norwich, NR4 7UH, UK Wheat is the world’s second largest crop after corn, yet 21.5% of the global yield is lost to pest and pathogens annually. Wheat stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici (Pst), is responsible for more than 15 million tons of yield loss every year. To limit pathogen impact, wheat and its relatives have evolved resistance genes capable of recognizing pathogen presence and triggering appropriate immune responses in the host. The wild grass Aegilops tauschii is the donor of the D sub-genome of modern bread wheat and represents a great source of genetic diversity for breeding programmes. We screened a panel composed of 151 genetically diverse A. tauschii accessions at the seedling stage for stripe rust resistance using 29, 3, and 2 Pst races from Canada, USA, and UK, respectively. British Columbia regional meeting, 2021 2