Characterization of the Functions of Starch Synthase IIIb Expressed in the Vegetative Organs of Rice (<i>Oryza sativa</i>L.)
Characterization of the Functions of Starch Synthase IIIb Expressed in the Vegetative Organs of Rice (<i>Oryza sativa</i>L.)
复制标题
水稻营养器官中表达的淀粉合酶 IIIb 的功能表征（<i>Oryza sativa</i>L.）
DOI：
10.1093/pcp/pcac143
复制
发表时间：
2022
影响因子：
4.9
通讯作者：
Fujita Naoko
中科院分区：
文献类型：
--
作者：
Morita Ryutaro;Crofts Naoko;Miura Satoko;Ikeda Ken-ichi;Aoki Naohiro;Fukayama Hiroshi;Fujita Naoko
水稻在粮食生产中具有重要意义，是研究胚乳淀粉生物合成机制的模式C3作物。然而，对水稻营养器官中淀粉的生物合成知之甚少。本研究利用水稻淀粉合成酶（Starch synthase，SS）Ⅲ b基因插入Tos 17突变体和anss 1突变体，探讨了SS同工酶在淀粉合成中的作用差异。SS的非变性聚丙烯酰胺凝胶电泳（PAGE）/活性染色，使用LS和LB的突变体，显示最低的迁移SS活性带的凝胶上来自SSIIb活性和两个oss 3b突变体没有检测到。ss 3b突变体LS淀粉的表观直链淀粉含量增加。此外，链长分布和尺寸排阻色谱分析表明，SSIIb和SSI分别在LS和LB中合成支链淀粉的B2-B3链和A-B 1链。有趣的是，我们还发现，淀粉含量下降的LS和LB的ss 3b突变体，虽然SSI缺乏并不影响淀粉水平。这些结果表明，SSIIb在胚乳中与SSIIIa相似，在LS和LB中合成支链淀粉的长链，而SSI在营养器官中与胚乳中相似，合成支链淀粉的短链。
Rice is the model C3crop for investigating the starch biosynthesis mechanism in endosperm because of its importance in grain production. However, little is known about starch biosynthesis in the vegetative organs of rice. In this study, we used novel rice mutants by insertingTos17into thestarch synthase (SS) IIIbgene, which is mainly expressed in the leaf sheath (LS) and leaf blade (LB), and anss1mutant to clarify the differences in roles among SS isozymes during starch biosynthesis. Native polyacrylamide gel electrophoresis (PAGE)/activity staining for SS, using LS and LB ofssmutants, revealed that the lowest migrating SS activity bands on the gel were derived from SSIIIb activity and those of twoss3bmutants were not detected. The apparent amylose content of LS starch ofss3bmutants increased. Moreover, the chain-length distribution and size-exclusion chromatography analysis usingssmutants showed that SSIIIb and SSI synthesize the B2–B3chain and A–B1chain of amylopectin in the LS and LB respectively. Interestingly, we also found that starch contents were decreased in the LS and LB ofss3bmutants, although SSI deficiency did not affect the starch levels. All these results indicated that SSIIIb synthesizes the long chain of amylopectin in the LS and LB similar to SSIIIa in the endosperm, while SSI synthesizes the short chain in the vegetative organ as the same in the endosperm.