Title: "Intermediate" seed storage physiology: populus as a natural model system Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2011
Publication Date: April 10, 2011
Citation: Walters, C.T., Hill, L.M., Volk, G.M., Haiby, K. 2011. "Intermediate" seed storage physiology: populus as a natural model system. Meeting Abstract. International Society for Seed Science, Bahia, Brazil Apr 10-15, 2011. pp. 280. Technical Abstract: “Intermediate” seeds are short lived because they have low tolerance to the combined stresses of low moisture and temperature during storage. We hypothesize that intermediate seeds either 1) exhibit intermediate sensitivity to desiccation compared to orthodox and recalcitrant seeds; 2) are damaged by subfreezing temperatures as a result of first order phase changes (i.e., crystallization) of water or lipids; 3) have unstable glassy states, making them relatively unresponsive to low temperature effects, or 4) fail recover after storage. Seeds of Populus sp. age very quickly in storage, dying within 2 months when stored at room temperature (seeds of most specie usually survive at least 1 year) and within 3-5 years if stored in the freezer (seeds of most species usually survive at least 75 years). Hence, physiology of Populus seeds is consistent with attributes of intermediate seed storage behavior. Through experiments on Populus seed responses to stress challenges, we rule out hypothesis #1 because desiccation tolerance of Populus seeds is comparable to orthodox seeds; an optimum moisture range for storage exists between 13 and 30% RH. We also rule out hypothesis #2 because Populus seeds did not exhibit unusual water or lipid crystallization properties. Hypothesis #3 could not be ruled out because Populus seeds exhibited a rather shallow temperature coefficient, and insensitivity to temperature was more apparent as seeds became older. Populus is the first tree species with a fully sequenced genome, and this model system status provides the opportunity to evaluate how storage and aging affects the pattern of gene expression in recovering seedlings. We believe that understanding the physiology of Populus seeds will shed light on the stresses and responses to stress that contribute to the intermediate category of seed storage behavior.