John Innes Institute and Institute of Plant Science Research, Colney Lane, NR4 7UH, Norwich, UK.
Planta. 1990 Feb;180(3):420-8. doi: 10.1007/BF00198795.
The aim of this work was to discover why pea (Pisum sativum L.) embryos recessive at the r locus (rr) have a higher lipid content than embryos dominant at this locus (RR). The r locus is a gene encoding starch-branching enzyme, rr embryos have a much lower activity of this enzyme than RR embryos, and hence a reduced rate of starch synthesis. The higher lipid content of rr embryos must be a consequence of this. We suggest that neither differences in the availability of substrate for lipid synthesis as a consequence of different rates of starch synthesis, nor differences in the capacity of the pathway for malonyl-CoA synthesis, account for the different lipid contents of RR and rr embryos. Lipid contents of the two sorts of embryo first diverge at a much later stage in development than divergence in starch content. Amounts of pyruvate and acetate, and activities of enzymes that convert triose phosphate to malonyl CoA are the same in the two sorts of embryo. Most of the lipid in developing embryos is polar, structural lipid, and polar lipid accounts for a large proportion of the difference in lipid content between the two sorts of embryo. This difference in structural-lipid content reflects considerable structural differences between the two sorts of embryo and is presumably the consequence of differences in rates of lipid turnover.
这项工作的目的是探究豌豆（Pisum sativum L.）隐性 rr 等位基因（rr）胚比显性 RR 等位基因胚具有更高脂质含量的原因。r 基因座编码淀粉分支酶，rr 胚的这种酶活性比 RR 胚低得多，因此淀粉合成的速率降低。rr 胚中较高的脂质含量一定是由此产生的。我们认为，不论是由于淀粉合成速率不同导致合成脂质的底物可用性的差异，还是丙二酰辅酶 A 合成途径的能力的差异，都不能解释 RR 和 rr 胚中不同的脂质含量。两种胚的脂质含量在发育过程中比淀粉含量的差异出现得晚得多。两种胚中丙酮酸和乙酸盐的含量以及将三碳磷酸转化为丙二酰辅酶 A 的酶的活性相同。发育中的胚胎中的大部分脂质是极性的，结构性脂质，极性脂质占两种胚之间脂质含量差异的很大一部分。这种结构性脂质含量的差异反映了两种胚之间相当大的结构差异，可能是由于脂质周转率的差异造成的。
