Storage reserve mobilization during low temperature germination and early seedling growth in Brassica napus | [Mobilisation des reserves pendant la germination a basse temperature et la croissance des plantules de Brassica napus]
1999
Nykiforuk, C.L. (University of Lethbridge (Canada). Department of Chemistry and Biochemistry) | Johnson Flanagan, A.M.
In western Canada, oilseed rape (Brassica napas L. var. oleifera cv. Westar) is seeded during the early months of spring, when ambient temperatures are well below the optimum. This can result in poor seedling emergence. The objectives of the present study were to determine which developmental stages are sensitive to low temperature and whether the effects are thermal or developmental in nature. Seed was germinated at 22, 10 and 6 degrees C. Fresh weight changes and seedling growth were assessed on the basis of equal accumulated heat units, and the mobilization of storage reserves was assessed by employing antibodies against isocitrate lyase (ICL; EC 4.1.3.1), oleosin and cruciferin. Additionally, de novo protein synthesis was determined by quantifying the incorporation of methionine via in vivo labelling. Low temperature resulted in poor germination and early seedling growth with phase II of germination being most sensitive. At 10 degrees C, there was a temporal delay in germination that did not affect the overall success of germination. This was a thermal effect as seed at the lower temperatures required the equivalent of 16-24 degree days before germination occurred. Also, seedling growth at 10 degrees C was lower in comparison to seedlings grown at 22 degrees C. Seed at 6 degrees C displayed slow and incomplete germination and poor seedling growth as a result of both thermal and developmental effects
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