Abstract Detail

Biotic and abiotic stress

Hart, Ashley [1], Hamilton, Jill [1], El Kayal, Walid [1], Cooke, Janice E. K. [1].

Cellular Level Changes that Occur During White Spruce Growth Cessation and Dormancy Acquisition.

The characteristic temperate and boreal climates of northern latitudes impose a requirement for perennial species such as white spruce (Picea glauca) to seasonally regulate growth and development. Growth cessation and dormancy acquisition are adaptations that enables the tree to endure the unfavorable conditions of winter, promoting long-term survival of white spruce. Environmental cues of day length and temperature act as seasonal regulators of the active growth to dormant stage transition for perennial species. While shorter days accelerate this transition in white spruce, trees will undergo bud formation, growth cessation and transition to dormancy even in the absence of autumnal-associated environmental cues. Most of our understanding of seasonal activity-dormancy transitions in perennial species has been drawn from independent studies of buds or stems. Few studies have examined the relative timing of growth cessation across tissues, or explored whether photoperiod and temperature differentially impact the timing of growth cessation in these tissues. The objectives of this study are to (1) determine how growth cessation and other cellular changes are coordinated between buds, stems and roots, (2) ascertain how short photoperiod and low temperatures affect these events across tissues, and (3) correlate cellular-level changes with changes in expression of reporter genes associated with the activity-dormancy transition. Tissues for microscopy and gene expression analyses were collected over a 15 week period from two year old white spruce seedlings subjected to four contrasting environmental conditions: long days/warm temperatures, short days/warm temperatures, long days/cool temperatures, and short days/cool temperatures. Microscopy analyses revealed major developmental changes that occurred during the growth to dormancy transition in buds, stems and roots. Histochemical analyses were used to compare accumulation of nutrient reserves in these tissues over time. We used Periodic Acid Schiff’s stain to visualize mitotic divisions and compute a mitotic index, allowing for inference of the timing of growth cessation. In the near future, the role of genes hypothesized to play roles in the activity-dormancy transition will be examined, using quantitative RT-PCR to measure transcript abundance and in situ hybridization to determine spatial patterns of transcript accumulation. Changes in gene expression will be related to developmental events captured in the microscopy analyses. The outcomes of this study will improve our understanding of the relationship between regional climatic conditions and the developmental changes that occur during dormancy acquisition in this ecologically and economically important forest tree species, particularly under scenarios of climate change.

1 - University of Alberta, Biological Sciences, Biological Sciences Building, University of Alberta, Edmonton, AB, T6G 2E9, Canada

Keywords:
none specified

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PBA002
Abstract ID:468
Candidate for Awards:CSPB President's Award for Best Student Presentation