Page 178 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

severity in both controlled environment and field trials, but the optimal application rates and mechanism(s)
of pathogen suppression require further investigation. One hypothesis was that application of boron
increased cell wall thickness, making plants less susceptible to pathogen colonization and development.
In the current study, the effect of boron on clubroot severity and plant defense was examined in four lines
of B. napus in growth room studies and gene expression analysis. Controlled environment studies
-1
demonstrated that an application equivalent to 16 kg B ha provided a modest but consistent reduction in
clubroot severity. The putative boron-tolerant line Mytnickij had lower clubroot severity than Westar, ACS-
N39 and another putative boron-tolerant line, Prota. Further studies were done on plants that received
boron at a rate of 8 kg B ha as there was concern about phytotoxicity at higher rates. The application of
-1,
-1
8 kg B ha had little or no effect on cell wall properties in stained root cross-sections of young plants that
were analysed using ASSESS image analysis software. Substantial changes associated with application
-1
of 8 kg B ha were observed in genes involved in cell wall synthesis, pathogen defense, and abiotic
stress tolerance. Several genes in the phenylpropanoid pathway, responsible for synthesizing a wide
variety of secondary metabolites crucial in plant defense, including flavonoids and lignin, were
differentially regulated with the addition of boron. Also, genes associated with ethylene biosynthesis
(involved in hormonal defence signaling) and boron transporters were upregulated in response to boron
treatment in combination with P. brassica infection. This highlights the role of even moderate rates of
boron in enhancing resistance to P. brassicae. The results suggest that boron can be important for plant
defense. These results support previous reports that application of boron reduced clubroot severity,
possibly by improving the crop’s defense response during colonization by P. brassicae.

[O146] BACTERIAL LEAF STREAK SURGE ON THE CANADIAN PRAIRIES: INSIGHTS AND
MANAGEMENT STRATEGIES. Shaheen Bibi , Malini Jayawardana , and Dilantha Fernando .
1
1
1
1 Department of Plant Science, Agriculture Building 66 Dafoe Road, University of Manitoba, Winnipeg, MB
R3T 2N2
Correspondence to: dilantha.fernando@umanitoba.ca

Bacterial Leaf Streak (BLS) poses an increasing challenge for wheat and barley growers in the Canadian
Prairies. This emerging disease is caused by Xanthomonas translucens pv. undulosa and Xanthomonas
translucens pv. translucens. Over the recent years, the spread of this disease has intensified, resulting in
notable crop losses, occasionally reaching levels as high as 40% yield loss. To tackle this growing issue,
we aim to understand the mechanisms behind BLS transmission and develop effective management
strategies. In pursuit of our objective, we have collected disease samples from diverse regions across
Canada including Alberta and Manitoba. Bacteria were isolated from symptomatic lesions on plant leaves
and spikelets using semi-selective media. The identification of bacteria to pathovar levels was conducted
through multiplex PCR, utilizing primers cbsA-1, cbsA-2, cbsA-3, and cbsA-4 to amplify the cbsA gene
while S8.pep amplified the Xtu unique peptidase gene. In our initial screening, we observed that the
majority of the disease is attributed to Xanthomonas translucens pv. undulosa. In addition to these
diagnostic initiatives, we are also exploring novel approaches to manage BLS. This involves assessing
the efficacy of well-characterized biocontrol agents, Pseudomonas brassicacearum strain DF41 and
Pseudomonas chlororaphis strain PA23, against the pathogen. Our preliminary findings are encouraging,
indicating that these agents hold potential as a sustainable approach to mitigating BLS. Furthermore, our
initial screening of Canadian wheat varieties aims to uncover any resistance to BLS. Our early findings
suggest that the disease affects most Canadian wheat varieties. In addition, Multilocus sequence analysis
(MLSA) of four housekeeping genes (rpod, dnaK, fyuA and gyrB) will be used to evaluate the genetic
diversity of the Canadian isolates from wheat and barley. This underscores the immediate necessity for
comprehensive research to determine the most effective and timely management practices for controlling
BLS.

[O147] A SURVEY FROM 2006-2023 TO STUDY THE STATE AND PREVALENCE OF FUSARIUM
HEAD BLIGHT DISEASE ON WHEAT IN ALBERTA. Monika Dayarathne , Michael Harding , and
2
1
1 1
Dilantha Fernando . Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada,
R3T2N2; Crop Diversification Centre South, Alberta Agriculture and Irrigation, 301 Horticulture Station
2
Road East, Brooks, AB, Canada T1R 1E6
Correspondence to: dilantha.fernando@umanitoba.ca

177