Abscisic acid enhances starch degradation and sugar transport in rice upper leaf sheaths at the post-heading stage
Journal
Acta Physiologiae Plantarum
Pages
1-8
Date Issued
2012
Author(s)
Chen, H.-J.
Abstract
Leaf sheaths of higher position leaves (upper leaf sheaths) on rice (Oryza sativa L.) stems function as temporary starch storage organs at the pre-heading stage. Starch is quickly accumulated in upper leaf sheaths before heading, but the storage starch is degraded at the post-heading stage to provide the carbon source for developing grains. Abscisic acid (ABA) is a key plant hormone to control plant development and stress responses. This study found that ABA content in upper leaf sheaths was significantly increased at the stage after panicle exsertion and that the pattern of ABA increase was negatively correlated with changes in starch content. Exogenous ABA reduced starch content in leaf sheaths while the activities of starch degradation enzymes (i.e., α-amylase/EC 3.2.1.1, β-amylase/ EC 3.2.1.2) increased in ABA-treated leaf sheaths and sucrose transporter gene expression was up-regulated. However, ABA repressed the activities of some starch biosynthesis enzymes (i.e., ADP-glucose pyrophosphory-lase/EC 2.7.7.27, granule-bound starch synthase/EC 2.4.1.11) in leaf sheaths. These results suggest that ABA plays an important role in promoting starch degradation and sucrose remobilization in upper leaf sheaths at the post-heading stage.
Type
journal article