Page 304 - PC2019 Program & Proceedings

PLANT CANADA 2019

P181. Potential use of Acer saccharum leaf extract for the control of lettuce bacterial leaf spot and
varnish spot
*
Delisle-Houde, M. ; R. Tweddell
Université Laval

Extracts prepared from wastes of different forest species (Abies balsamea, Acer rubrum, Acer saccharum,
Alnus incana subsp. rugosa, Larix laricina, Picea glauca, Picea mariana, Pinus banksiana, Pinus
strobus, Populus tremuloides, Prunus avium, Quercus rubra) were tested for their antibacterial activity
against Pseudomonas cichorii (Swingle) Stapp (the causal agent of lettuce varnish spot) and
Xanthomonas campestris pv. vitians (Brown) Dye (the causal agent of lettuce bacterial leaf spot). Extracts
were first screened for their antibacterial activities using the in vitro disk diffusion assay. According to
the inhibition zone, A. saccharum leaf extract and, to a lesser extent, Q. rubra and A. incana subsp.
−1
−1
rugosa bark extracts showed antibacterial activities. Acer saccharum leaf extract (0.8 g L , 1.6 g L , 3.2
−1
g L ) was further tested for its effect on the development of varnish spot and bacterial leaf spot on lettuce
plants grown in greenhouse. Foliar sprays of A. saccharum leaf extract at a concentration of 3.2 g L −1
reduced significantly (P≤ 0.05) bacterial leaf spot severity and, in one experiment out of two, varnish spot
severity. This study points out for the first time the possibility of exploiting A. saccharum leaf extract for
the control of lettuce bacterial leaf spot and varnish spot.

Maxime Delisle-Houde (maxime.delisle-houde.1@ulaval.ca)

P182. Genetic mapping of adult plant leaf rust resistance in spring wheat line BW278
2
*1
2
3
Lewarne, M. ; B. McCallum ; C. Hiebert ; C. McCartney
1 University of Manitoba
Agriculture and Agri-Food Canada
2
3 Morden Research and Development Centre
Leaf rust caused by fungal pathogen Puccinia triticina is a widespread disease of wheat that affects both
yield and quality. The preferred method of leaf rust control is through genetic host resistance as it
provides protection throughout the growing season without additional costs to the producer and
environment. To date there are over 80 characterized leaf rust resistance genes, the majority of which are
race-specific and condition resistance to a subset of P. triticina races. Lr46, a non-race specific adult plant
resistance (APR) gene located on the long arm of chromosome 1B, is thought to be present in spring
wheat line BW278. A doubled haploid (DH) population (Superb/BW278) and a recombinant inbred line
(RIL) population (BW278/AC Foremost) were inoculated under field conditions with an epidemic mix of
P. triticina races, as well as indoors with P. triticina race MBDS. Initial results suggest that a single leaf
rust (Lr) APR gene is segregating at the adult plant stage in both populations. The objectives of the
current study include: (i) confirm the presence of Lr46 in BW278, (ii) genetically map the resistance and
identify closely linked genetic markers for future use in breeding programs and (iii) screen a panel of
Canadian wheat cultivars to determine the distribution of Lr46.

Mallorie Lewarne (lewarnem@myumanitoba.ca)

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