Sucrose synthases are not involved in starch synthesis in Arabidopsis leaves.
Sucrose synthases are not involved in starch synthesis in Arabidopsis leaves.
复制标题
DOI：
10.1038/s41477-022-01140-y
复制
发表时间：
2022-05
期刊：
影响因子：
18
通讯作者：
Niittyla, Totte
中科院分区：
文献类型：
--
作者：
Funfgeld, Maximilian M. F. F.;Wang, Wei;Ishihara, Hirofumi;Arrivault, Stephanie;Feil, Regina;Smith, Alison M.;Stitt, Mark;Lunn, John E.;Niittyla, Totte
许多植物白天在叶子中积累短暂的淀粉储备，以缓冲碳水化合物的供应以应对波动的光照条件，并为夜间的生存提供碳和能量。人们普遍认为，暂时性淀粉是由叶绿体中的 ADP-葡萄糖 (ADPG) 合成的。然而，ADPG 是由 ADPG 焦磷酸化酶在叶绿体中产生的共识受到了一项有争议的提议的挑战，即 ADPG 主要在细胞质中（可能是由蔗糖合酶 (SUS)）产生，然后导入叶绿体中。为了解决这一长期存在的争议，我们批判性地重新审查了似乎与共识途径相冲突的实验证据。我们发现，当在叶子采样过程中采取预防措施避免人为变化时，叶肉细胞中缺乏 SUS 活性的拟南芥突变体（四重 sus1234）或没有 SUS 活性（六重 sus123456）具有野生型 ADPG 和淀粉水平，而在淀粉合成的共有叶绿体途径中被阻断的 pgm 和 adg1 突变体中，ADPG 低 20 倍。我们得出结论，叶子中淀粉合成所需的 ADPG 主要由叶绿体中的 ADPG 焦磷酸化酶合成。突变体分析表明，蔗糖合酶对拟南芥叶片中的瞬时淀粉合成没有实质性贡献，解决了关于光合代谢最重要途径之一的长达 20 年的争议。
Many plants accumulate transitory starch reserves in their leaves during the day to buffer their carbohydrate supply against fluctuating light conditions, and to provide carbon and energy for survival at night. It is universally accepted that transitory starch is synthesized from ADP-glucose (ADPG) in the chloroplasts. However, the consensus that ADPG is made in the chloroplasts by ADPG pyrophosphorylase has been challenged by a controversial proposal that ADPG is made primarily in the cytosol, probably by sucrose synthase (SUS), and then imported into the chloroplasts. To resolve this long-standing controversy, we critically re-examined the experimental evidence that appears to conflict with the consensus pathway. We show that when precautions are taken to avoid artefactual changes during leaf sampling, Arabidopsis thaliana mutants that lack SUS activity in mesophyll cells (quadruple sus1234) or have no SUS activity (sextuple sus123456) have wild-type levels of ADPG and starch, while ADPG is 20 times lower in the pgm and adg1 mutants that are blocked in the consensus chloroplastic pathway of starch synthesis. We conclude that the ADPG needed for starch synthesis in leaves is synthesized primarily by ADPG pyrophosphorylase in the chloroplasts. Mutant analysis shows that sucrose synthase makes no substantial contribution to transitory starch synthesis in Arabidopsis leaves, resolving a 20-year-old controversy about one of the most important pathways of photosynthetic metabolism.
登录
查看更多内容
影响因子：
7.2
作者：
Figueroa, Carlos M.;Feil, Regina;Lunn, John E.
通讯作者：
Lunn, John E.
DOI：
10.1073/pnas.0900689106
发表时间：
2009-08-04
影响因子：
11.1
作者：
Barratt, D. H. Paul;Derbyshire, Paul;Smith, Alison M.
通讯作者：
Smith, Alison M.
影响因子：
11.6
作者：
Gibon, Y;Blaesing, OE;Stitt, M
通讯作者：
Stitt, M
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF
影响因子：
7.4
作者：
Kunz, Hans-Henning;Zamani-Nour, Shirin;Gierth, Markus
通讯作者：
Gierth, Markus