Plant Physiology Research Group, Department of Biology, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
Plant Physiol. 1987 Jun;84(2):381-5. doi: 10.1104/pp.84.2.381.
Previous work has indicated that changes in gibberellin (GA) metabolism may be involved in chilling-induced release from dormancy in somatic embryos of grape (Vitis vinifera L. x V. rupestris Scheele). We have chilled somatic embryos of grape for 2, 4, or 8 weeks, then incubated them with [(3)H]GA(4) (of high specific activity, 4.81 x 10(10) becquerel per millimole) for 48 hours at 26 degrees C. Chilling had little effect on the total amount of free [(3)H]GA-like metabolites formed during incubation at 26 degrees C, but did change the relative proportions of individual metabolites. The amount of highly water-soluble [(3)H] metabolites formed at 26 degrees C decreased in embryos chilled for 4 or 8 weeks. The concentration of endogenous GA precursors (e.g., GA(12) aldehyde-, kaurene-, and kaurenoic acid-like substances) increased in embryos chilled for 4 or 8 weeks. Treatment with abscisic acid (ABA) (known to inhibit germination in grape embryos) concurrent with [(3)H]GA(4) treatment at 26 degrees C, reduced the uptake of [(3)H] GA(4) but had little effect on the qualitative spectrum of metabolites. However, in the embryos chilled for 8 weeks and then treated with ABA for 48 hours at 26 degrees C, there was a higher concentration of GA precursors than in untreated control embryos. Chilled embryos thus have an enhanced potential for an increase in free GAs through synthesis from increased amounts of GA precursors, or through a reduced ability to form highly water-soluble GA metabolites (i.e., GA conjugates or polyhydroxylated free GAs).
先前的研究表明，赤霉素（GA）代谢的变化可能与体细胞胚休眠解除有关。我们将葡萄体细胞胚冷处理 2、4 或 8 周，然后在 26°C 下用[（3）H]GA（4）（高比活度，4.81×10（10）贝克勒尔/毫摩尔）孵育 48 小时。冷处理对 26°C 孵育过程中形成的游离[（3）H]GA 样代谢物总量影响不大，但改变了单个代谢物的相对比例。在 26°C 下形成的高度水溶性[（3）H]代谢物的量在冷处理 4 或 8 周的胚胎中减少。内源性 GA 前体（例如，GA（12）醛、贝壳杉烯和贝壳杉烯酸样物质）的浓度在冷处理 4 或 8 周的胚胎中增加。在 26°C 下用脱落酸（ABA）（已知抑制葡萄胚胎萌发）处理与[（3）H]GA（4）同时处理，减少了[（3）H]GA（4）的摄取，但对代谢物的定性谱几乎没有影响。然而，在冷处理 8 周然后在 26°C 下用 ABA 处理 48 小时的胚胎中，GA 前体的浓度高于未处理的对照胚胎。因此，冷处理的胚胎通过增加 GA 前体的量合成游离 GA，或通过降低形成高度水溶性 GA 代谢物（即 GA 缀合物或多羟基化游离 GA）的能力，增强了游离 GA 增加的潜力。
