Two β-amylase genes, OsBAM2 and OsBAM3, are involved in starch remobilization in rice leaf sheaths
Two β-amylase genes, OsBAM2 and OsBAM3, are involved in starch remobilization in rice leaf sheaths
复制标题
DOI：
10.1080/1343943x.2016.1140008
复制
发表时间：
2016-01-01
影响因子：
2.5
通讯作者：
Michiyama, Hiroyasu
中科院分区：
文献类型：
--
作者：
Hirano, Tatsuya;Higuchi, Takayuki;Michiyama, Hiroyasu
为了确定抽穗后水稻叶鞘中淀粉降解的机制，我们研究了 OsBAM2 和 OsBAM3（编码质体靶向活性 β-淀粉酶亚型）在叶鞘中淀粉再动员中的功能。旗叶以下的第二叶鞘(第三叶鞘)中淀粉含量在旗叶出苗期达到峰值，并逐渐下降，直至抽穗后15 d。第三叶鞘中OsBAM2和OsBAM3的mRNA水平从剑叶出苗期到抽穗期淀粉含量开始下降。然而，这些 mRNA 水平在标题后并不总是保持高水平。 OsBAM2或OsBAM3的过表达显着抑制了第三叶鞘中的淀粉积累，表明OsBAM2和OsBAM3在水稻叶鞘中的淀粉降解中发挥作用。相反，在OsBAM2或OsBAM3的敲低植物和非转基因野生型植物之间没有检测到第三叶鞘中淀粉含量的显着差异。我们的结果表明，OsBAM2 或 OsBAM3 单个基因表达的减少不会导致叶鞘中淀粉过量积累，这可能是因为另一个基因的互补功能或其他编码淀粉降解基因的作用。
To identify mechanisms of starch degradation in rice leaf sheaths at the post-heading stage, we investigated the function of OsBAM2 and OsBAM3, which encode plastid-targeted active beta-amylase isoforms, in starch remobilization in leaf sheaths. The starch content in the second leaf sheaths below the flag leaf (the third leaf sheaths) peaked at the flag leaf emergence stage and gradually decreased until 15 days after heading. The mRNA levels of OsBAM2 and OsBAM3 in the third leaf sheaths increased from the flag leaf emergence stage to the heading stage when the starch content began to decrease. However, these mRNA levels did not always remain high during post-heading. Overexpression of OsBAM2 or OsBAM3 markedly repressed starch accumulation in the third leaf sheaths, showing that OsBAM2 and OsBAM3 function in starch degradation in rice leaf sheaths. In contrast, no significant differences in starch content in the third leaf sheaths were detected between knockdown plants of OsBAM2 or OsBAM3 and non-transgenic wild-type plants. Our results suggest that reduced expression of the individual genes, OsBAM2 or OsBAM3, does not result in excess accumulation of starch in the leaf sheaths, probably because of the complementary function of another gene or the action of other genes encoding starch-degrading.