Page 170 - PC2019 Program & Proceedings

PLANT CANADA 2019

S125. Relationship between foliar symptoms and gene expression induced by Pear Decline
phytoplasma
Kaviani, M.; P.H. Goodwin; D. Hunter
University of Guelph

Pear tree selections developed at AAFC with PD phytoplasm infection show either leaf curling (selection
9328-1) or leaf reddening (selection 8824-1) indicating different responses to infection. PD populations in
the two selections were not significantly different, except for ten time higher numbers in roots of selection
9328-1 than 8824-1 indicating greater susceptibilty. Gene expression between non-infected and PD-
infected tissues of both selections was determined for sucrose synthase and acid invertase, which are
affected by localized changes in sugars, and alcohol dehydrogenase, chitinase class III, phenylalanine
ammonia-lyase and phloem protein2, which are affected during PAMP triggered immunity. Greater up-
regulation of gene expression in PD-infected tissues was observed in selection 8824-1 for sucrose
synthase in leaves, acid invertase in leaves and roots, alcohol dehydrogenase in shoots, chitinase in all
tissues, and phloem protein2 in roots. In contrast, greater up-regulation in PD-infected selection 9328-1
was only observed for sucrose synthase, acid invertase and phenylalanine ammonia-lyase in shoots. The
results indicate that leaf reddening may be due to an accumulation of anthocyanins as part of a greater
PAMP triggered immunity response in selection 8824-1, while leaf curling in selection 9328-1 may be
due to water stress because of more dysfunctional phloem.

Mina Kaviani (minakavyani@gmail.com)

S126. Update on Manitoba potato and horticultural crops disease and insect pests in 2018.
Bisht, V. .
Manitoba Agriculture

Potato and horticultural crops are high value and high input crops with significant disease and insect pest
risks. The 2018 cropping season had normal spring planting. The growing season was generally dry with
extended warm periods, and just prior to harvest a prolonged wet period, followed with freezing
temperatures. The foliar diseases were generally lower than normal, but Verticillium wilt and black dot
(Colletrotrichum coccodes) diseases were more extensive. In-vitro testing identified some fungicides
effective against C. coccodes. Late blight was not found in 2018. Colorado potato beetles appeared in
increasing numbers even after seed treatments. Aphid numbers in traps were significantly lower than
normal, reducing risk of mosaic diseases in seed potato. European corn borer injury was noticeable in a
few fields, but did not warrant insecticide application. Aster leafhopper (ALH) numbers in traps were also
low on potato and carrots, resulting in lower ALH transmitted diseases. Cauliflower blackrot disease was
not an issue in 2018. On strawberry and raspberry Botrytis grey mold was found at low levels; probably
due to high temperatures near harvest time. Verticillium wilt/stripe was recorded in many crucifer
vegetables in infested trial plots. End of the crop season was marked by severe frost damage to many
crops. This resulted in nearly 6000 acres of potato and vegetables not being harvested, and soft rot issues
in potato storages.

Vikram Bisht (vikram.bisht@gov.mb.ca)

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