Page 175 - PC2019 Program & Proceedings

PLANT CANADA 2019

S135. Cryopreservation and reintroduction of Hill’s thistle (Cirsum hillii) to its natural habitat
Bi, W.; A. Saxena; M. Shukla; P. Saxena
University of Guelph

Hill’s thistle (Cirsum hillii) is a perennial species native to North America which has been threatened in
Canada since 2008. The aim of this study was to establish efficient protocols for cryopreservation and
long-term conservation of in-vitro grown shoot tips of Hill’s thistle using droplet-vitrification method,
and reintroduction of regenerated plants to their natural habitat in Bruce Peninsula National Park. Shoot
tips with 5-6 leaf primordia were successfully cryopreserved using a plant vitrification solution (PVS3, 50
% sucrose and 50 % glycerol; w/v) after keeping them for 20 mins in the loading solution containing 1.9
M glycerol and 0.5 M sucrose. Shoot tips were revived from the cryobank with a 96% survival efficiency.
Frozen shoot tips were re-warmed in a solution of 0.8 M sucrose and cultured in the shoot multiplication
medium. Currently, 200 shoot tips have been cryopreserved in the GRIPP cryobank for long-term storage.
Of these cryopreserved shoot tips, 75 were recovered and fully developed into plants with well-formed
roots and re-introduced into their habitat at the Bruce Peninsula National Park in the summer of 2018. The
survival efficiency of these plants, evaluated after four months of field transplant, was more than 99%.
Our results demonstrated that the droplet-vitrification procedure developed in this study is an efficient
method of cryopreservation for long-term conservation and may also be used for recovery of other
endangered plant species.

Wenlu Bi (wenlubi@uoguelph.ca)

S136. A comparison of the vascularization and morphology of floral nectaries in North American
asters and goldenrods of tribe Astereae
*
Braun, K. ; A. Davis
University of Saskatchewan

Representing over 25,000 species, it is of no surprise that members of Asteraceae can be found on all
continents except Antarctica. Within subfamily Asteroideae, the tribe Astereae has a nearly cosmopolitan
distribution, and is extremely diverse. This tribe is designated into clades based primarily on geographic
regions, and the North American clade contains many common species such as asters (Symphyotrichum
spp.) and goldenrods (Solidago spp.), among others. The inflorescences of these plants attract a large
variety of insects, which feed on nectar produced deep within the florets by structures called nectaries. In
Astereae, like most members of the family, these diminutive floral organs are of an annular shape,
surrounding the base of the style atop the inferior ovary, where nectar is secreted through modified
stomata. Although floral nectaries are thought to be ubiquitous in Asteraceae, they remain understudied.
Here, the morphology of floral nectaries of disk and ray florets within the tribe’s North American clade is
being examined using scanning electron microscopy. Also, to determine how sugars are delivered into the
nectary as a source for nectar production, we are using resin and paraffin sectioning to examine nectary
anatomy and vascularization. The results of this work will contribute to a better phylogenetic
understanding of the members within the largest tribe of this extremely diverse dicot family.

Kelton Braun (kelton.braun@usask.ca)

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