Page 306 - PC2019 Program & Proceedings

PLANT CANADA 2019

P185. Chitosan inhibits growth and development of Phytophthora nicotianae and induces tomato
resistance against this pathogen
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Falcón-Rodríguez, A. ; D. Csotales Menéndez ; Gonzalez-Peña Fundora, D. ; D. Vaillant Flores ; M.
Ochoa-Villarreal ; M. Martínez-Téllez
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1 National Institute of Agricultural Sciences (INCA); University of Lethbridge; Instituto de
Investigaciones de Sanidad Vegetal; Centro de Investigación en Alimentación y Desarrollo (CIAD)
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Chitosan is a glucosamine polymer with activity as an antimicrobial compound and also as an elicitor of
defense responses in plants. The effect of chitosan on different life cycle stages of Phytophthora
nicotianae, an Oomycete that causes severe damage in tobacco and tomato crops, was evaluated in the
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present study. Addition of this compound, from 0.5 to 2.5 g.L , to culture media decreased the isolates
mycelial growth. The colony pattern and the hyphae diameter were not affected by the polymer; however,
a reduction in the number of the sexual reproduction structures (oospores) was observed at the lowest
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concentration (0.5 g.L ) tested. Low chitosan concentration stimulated sporangia production, while high
concentrations reduced this number. The sporangia length/width ratio was not affected by the polymer.
Indirect germination of sporangia was completely abolished with 1.5 g.L of chitosan. Zoospores
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incubated with different polymer concentrations did not germinate and they were not able to infect tomato
plants roots at the lowest concentration tested (0.5 g.L ). Moreover, chitosan activated tomato plantlet
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protection against P. nicotianae infection when applied as a foliar application (0.1 and 1 g.L ) prior to
inoculation. The induced resistance was concurrent with increased activity of phenyl-propanoid pathway
markers. Taken together these results show that it is possible to control the spread of this pathogen in
solanaceous crops with the application of this compound.
Dianevys Gonzalez-Peña Fundora (dianevys.gonzalezpen@uleth.ca)

P186. Rotation with Aphanomyces-resistant pulse crops or intercropping with Brassicas to reduce
impact of Aphanomyces root rot on field pea
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Chatterton, S. ; S. Banniza ; R. Bowness ; M. Harding ; M. Hubbard ; L. Shaw ; S. Shirtliffe
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1 Agriculture and Agri-Food Canada; University of Saskatchewan; Alberta Agriculture and Forestry
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Agriculture and Forestry; Swift Current Research and Development Centre
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6 South East Research Farm

The oomycete pathogen Aphanomyces euteiches is a threat to field pea production on the Canadian
prairies. The only management strategy for Aphanomyces root rot is rotation away from susceptible hosts
(pea and lentil) for at least six – eight years. Field trials to evaluate the effect of rotation with resistant
pulse crops (soybean, faba bean, or chickpea) or intercropping with Brassica crops on disease severity and
inoculum potential were initiated in 2018. Trials were located in producer’s fields naturally infested with
A. euteiches. Rotation trials were conducted at six locations, and intercropping trials at two locations.
Disease severity, and levels of A. euteiches and select Fusarium spp. on the roots were assessed at two
time points. Depending on location, 5 – 325 oospores were produced per gram of pea root tissue. Faba
bean and soybean did not support A. euteiches, but low levels of oospores were produced on chickpea
roots at one location. Root rot occurred on faba bean, soybean and chickpea, but it was caused by
Fusarium spp., not A. euteiches. Intercropping with mustard or canola did not reduce disease levels on
pea nor the number of oospores in pea roots. However, land equivalence ratios for intercrops were
generally higher than monocrops. These field trials, that will also evaluate the effect of frequency of pea
on soil inoculum potential, will continue for four years.

Syama Chatterton (syama.chatterton@canada.ca)

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