Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, UK.
New Phytol. 2010 Aug;187(3):791-804. doi: 10.1111/j.1469-8137.2010.03311.x. Epub 2010 Jun 7.
*Starch accumulates early during embryo development in Arabidopsis and oilseed rape, then disappears during oil accumulation. Little is known about the nature and importance of starch metabolism in oilseed embryos. *Histochemical and quantitative measures of starch location and content were made on developing seeds and embryos from wild-type Arabidopsis plants, and from mutants lacking enzymes of starch synthesis and degradation with established roles in leaf starch turnover. Feeding experiments with [(14)C]sucrose were used to measure the rate of starch synthesis in oilseed rape embryos within intact siliques. *The patterns of starch turnover in the developing embryo are spatially and temporally complex. Accumulation is associated with zones of cell division. Study of mutant plants reveals a major role in starch turnover for glucan, water dikinase (absent from the sex1 mutant) and isoforms of beta-amylase (absent from various bam mutants). Starch is synthesized throughout the period of its accumulation and loss in embryos within intact siliques of oilseed rape. *We suggest that starch turnover is functionally linked to cell division and differentiation rather than to developmental or storage functions specific to embryos. The pathways of embryo starch metabolism are similar in several respects to those in Arabidopsis leaves.
*在拟南芥和油菜籽胚胎发育的早期，淀粉积累，然后在油脂积累过程中消失。关于油料胚中淀粉代谢的性质和重要性知之甚少。*对野生型拟南芥植株发育种子和胚胎进行了淀粉位置和含量的组织化学和定量测定，以及缺乏在叶片淀粉周转中具有既定作用的淀粉合成和降解酶的突变体。利用 [(14)C]蔗糖的饲喂实验测量了完整的油菜籽蒴果内油菜籽胚胎中淀粉合成的速率。*淀粉周转的模式在发育中的胚胎中具有空间和时间上的复杂性。积累与细胞分裂区相关。对突变体植物的研究表明，在淀粉周转中，葡聚糖、水二激酶（在 sex1 突变体中不存在）和β-淀粉酶同工型（在各种 bam 突变体中不存在）起着主要作用。在油菜籽完整蒴果内胚胎中淀粉积累和损失的整个时期都合成了淀粉。*我们认为淀粉周转与细胞分裂和分化有关，而不是与胚胎特有的发育或储存功能有关。胚胎淀粉代谢途径在几个方面与拟南芥叶片的途径相似。
