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Harvard Forest REU Symposium Abstract 2022
- Title: Non-Structural Carbohydrates’ Transition from Starch to Sugar Signals Spring Leaf-Out in Quercus rubra.
- Author: Miranda J Oseguera (Saint Joseph's University)
- Abstract:
Each year the timing of leaf-out in our temperate forests, or phenology, is a critical transition point for carbon models as climates warm globally. A tree’s leaves change the reflectivity of a plant. Thus altering the carbon and water cycle within the tree that connects to photosynthesis. Therefore, accurately predicting the timing of leaf budding in temperate species is essential to understanding climate change. It has been proposed that the movement and subsequent conversion of non-structural carbohydrates from starch to sugar is the initial signal in a tree branch for the tree to bud. Our project uses Northern Red Oak (Quercus rubra), as a model organism due to its vast range across eastern North America and abundance. Eight genotypes were selected and twigs were removed post-bud set in January 2022 and placed into twelve different treatments; 3 temperatures, extended chilling period or not, and 2 photoperiods. Twigs were collected at 6 phenophases, stored in a -80ºC freezer then freeze-dried and ground to a powder. We extracted sugar and starch using hot ethanol and read samples via colorimetric assays. After, we examined how the percent of total NSC in starch changed with phenophase and treatment using linear models in R. Preliminary data hints the conversion of starch to sugar in warming climates triggers spring leaf-out in Q. Rubra. A better understanding of pathways used to move and convert NSC can better understand how genetics and environment contribute to phenology. A comprehensive understanding of the mechanism used for leaf-out can then be used for prediction models in tree phenology and global climate.
- Research Category: Group Projects
