Page 127 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

rotation types including single, two, and more than two R genes without rotation or rotation with maximum
R gene diversity. Disease scores from each province were used to calculate the disease severity index
(DSI) and disease incidence (DI). In addition, canola stubble samples were used to isolate L. maculans
isolates for each year from 2019-2022 in Manitoba. The race structures of the L. maculans population
were determined by phenotyping with the differential set of Brassica species and genotyping by PCR. DSI
in all the rotations were significantly lower than the susceptible check Westar in Manitoba and Alberta. In
addition, the DSI and DIs for rotations of canola varieties with maximum R gene diversity was significantly
lower than two R genes (Rlm3/X or RlmLepR3/3) with no rotation in Manitoba and Alberta. Saskatchewan
followed the same DSI pattern except for no significant difference among susceptible control and canola
varieties LepR3/Rlm3 and Rlm3/RlmX with no rotation. Moreover, DSIs and DIs for rotations of canola
varieties with maximum R gene diversity were significantly lower than two R genes (Rlm3/X) with no
rotation in Saskatchewan. Interestingly, any rotation that included canola varieties exhibiting Rlm4 had
significantly lower DSIs and DIs with or without rotation. This was further supported by the pathogen race
structure where the abundant pathogen races all included AvrLm4. Although the data supports for a Rlm3
resistance breakdown in Canada, the impact can be reduced when Rlm3 is rotated with Rlm4. Overall,
this study demonstrates that the R gene rotation strategy is effective not only on delaying R gene
resistance breakdown, but also in reusing ineffective R genes in Canada.

[O51] DEVELOPMENT OF SALT TOLERANT ALFALFA (MEDICAGO SATIVA L.): FROM LAB TO
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2
FIELD. Bill Biligetu , Shanna Quilichini , and Surendra Bhattarai . Crop Development Center, College of
3 1
Agriculture and Bioresources, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8;
2 Salinity Laboratory, Agriculture and Agri-Food Canada, 1 Airport Road, Swift Current, SK S9H 3X2; and
3 SARDA Ag Research, Donnelly, AB Canada T0H 1G0
Correspondence to: bill.biligetu@usask.ca

Development of salt tolerant alfalfa cultivars has a significant value to reclaiming saline areas and
increasing forage production for animal feed. The objectives of this study were to understand
morphological, physiological, and molecular changes of alfalfa in response to salt stress and to develop
novel populations with improved salt tolerance. A series of experiments have been carried out over last
decade using Synchrotron beam lines, transcriptome analysis, salt lab tests, and field trials. Salt tolerant
populations showed greater germination percentage and seed vigor at 16 dS m E.C, and out-performed
-1
the check cultivars, especially under a high salinity of 20 dS m E.C, which indicated effectiveness of
-1
direct selection under high salt stress. Salt tolerant selection increased alfalfa leaf protein concentration,
and reduced fiber concentration, which was a favorable change in term of forage value. The pattern of
chlorine accumulation showed reduced ion accumulation in leaf tissues in the tolerant populations. In root
tissue, salt tolerant populations maintained greater number of differently expressed genes (DEGs) during
the first 27 h of salt stress, while the number of DEGs decreased for a susceptible population. We
developed KASP assay for the SNPs linked to the highly expressed genes. Our results showed that four
cycles of recurrent selection have accumulated certain salt resistant related favorable alleles in the alfalfa
breeding populations. Taken together, salt tolerance in alfalfa is a complex trait, and morphological,
genomic, and physiological indicators have been developed for future breeding use.

[O52] LEAF WATER RELATIONS AND OSMOTIC ADJUSTMENT OF CANADIAN WHEAT
CULTIVARS SUBJECTED TO DROUGHT. Gopal Sharma , Thorsten Knipfer , and Gurcharn S. Brar .
1,2
1
1
1 The University of British Columbia (UBC), Vancouver, Canada
2 University of Alberta, Edmonton, Canada
Correspondence to: gurcharn.brar@ualberta.ca

For wheat (Triticum aestivum), in previously published literature, sustained crop yield at limited soil water
has been linked to osmotic adjustment (OA) as one of the main drivers to minimize drought-induced
reductions in leaf hydration status and growth. Canada Western Red Spring (CWRS) cultivars are
typically grown in rainfed areas in northern plains region with milder climates, but ongoing climate change
has increased the frequency and intensity of drought event questioning how successful they are in
tolerating drought. The extent of OA and its relation to stomatal behavior, leaf roll, and kernel
development under periods of drought remain elusive for CWRS. For several commercially used Canada
Western Red Spring (CWRS) wheat cultivars (‘Superb’, ‘Stettler’, ‘AAC Viewfield’), OA was not found to
be a mechanism contributing to drought tolerance. In contrast, we found that sustained kernel weight

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