Page 208 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

remains unidentified and may be extinct (Clade 3). The genome assembly totals 1.34 Gb across 24
chromosomes with an N50 of 56.2 Mb, indicating a theoretical tetraploid genome size of 2.68 Gb over 48
chromosomes. Comparative transcriptomic analysis under cold stress between S. acaule and the
autotetraploid S. tuberosum cv. Atlantic shows that S. acaule exhibits fewer differentially expressed
genes. Analysis of the C-repeat binding factor (CBF) regulon, a transcription factor involved in regulating
cold response, reveals multiple gene duplications and gene losses.

[P8] STRATIFIED EFFECTS OF TILLAGE AND CROP ROTATION ON SOIL MICROBES IN C AND N
CYCLING AT TWO SOIL DEPTHS IN LONG-TERM CORN, SOYBEAN, AND WHEAT PRODUCTION.
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Yichao Shi , A. Claire Gahagan , Malcolm J. Morrison , Edward Gregorich , David R. Lapen , and Wen
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Chen . Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling
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Ave., Ottawa, ON K1A 0C6, Canada; and Department of Biology, University of Ottawa, Ottawa, 60 Marie
Curie Prv., Ottawa, ON K1N 6N5
Correspondence to: wen.chen@agr.gc.ca

Understanding the soil bacterial communities involved in carbon (C) and nitrogen (N) cycling can inform
beneficial tillage and crop rotation practices that address sustainability and crop production endpoints
simultaneously. Herein we evaluated the bacterial diversity, compositional structure, and functions
associated with C-N cycling for two soil depths (0-15 cm vs. 15-30 cm) under different long term soil
tillage (conventional tillage [CT] vs. no-till [NT]) and crop rotation (monocultures of corn, soybean, and
wheat vs. a corn-soybean-wheat rotation) production systems. Soil microbial communities were recovered
and characterized through metabarcoding the 16S rRNA gene V4-V5 regions using Illumina MiSeq
sequencing platform. The results showed that long-term NT farming reduced soil bacterial diversity at a
depth of 15-30 cm compared to CT, while no significant difference was observed at 0-15 cm. The
bacterial community differed significantly between the two soil depth under NT, but not under CT.
Notably, over 70% of the tillage-responded KEGG orthologs (KOs) abundance associated with C fixation
(primarily involved in reductive citric acid cycle) were higher under NT than under CT at both depths. NT
also enhanced N fixation-related bacteria at 0-15 cm and denitrification-related bacteria at both soil
depths. Crop type and rotation regimes had limited effects on bacterial diversity and compositional
structure; however, specific carbon-nitrogen (C-N) cycling genes varied among crops. For instance, three
KOs associated with the Calvin-Benson cycle for carbon fixation and four KOs related to various nitrogen
cycling processes were more abundant in wheat compared to corn and soybean, across both soil depths.
We conclude that for long-term corn, soybean, and wheat production systems, tillage practices had a
greater influence than crop rotation on the soil bacterial community by affecting its diversity,
compositional structure, and functionality, particularly regarding C and N cycling processes. Overall, this
study highlights the importance of integrated management practices that account for the combined effects
of tillage, crop rotation, and crop types on soil bacterial functional groups to enhance sustainable
agriculture.

*[P9] EXPLORING FUSARIUM WILT RESISTANCE IN BRASSICA GENOTYPES LINKED TO ROOT
ARCHITECTURAL TRAITS UNDER SEMI-HYDROPONIC CONDITIONS. Chunxiao Yang, Rudolph
Fredua-Agyeman, Kan-Fa Chang, Sheau-Fang Hwang, and Stephen E. Strelkov. Department of
Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB T6G 2P5, Canada
Correspondence to: chunxiao@ualberta.ca

Fusarium oxysporum, a soilborne fungal pathogen, causes wilt in a wide range of hosts, including canola
(oilseed rape; Brassica napus). The integration of genetic resistance with specific root system
architectural traits that are less favorable for disease development holds potential for improved control of
F. oxysporum. However, traditional methods for assessing host responses to this fungus in the soil
require substantial space, labor, and time. In this study, 38 genotypes of Brassica napus (AACC),
Brassica rapa (AA), and Brassica oleracea (CC) were evaluated for Fusarium wilt resistance. The
evaluation was conducted at the seedling stage under semi-hydroponic conditions. One-week-old
seedlings were inoculated using a root-dip method in a conidial suspension of a virulent F. oxysporum
isolate collected in Alberta in 2020. After 21 days in the semi-hydroponic system, seven root traits were
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measured using an EPSON Perfection V800 scanner and analyzed with WinRHIZO software. Strong
correlations were detected among the seven root traits measured. A significant, albeit relatively weak
negative correlation (coefficient value from -0.3 to -0.2), was identified between the root traits and

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