Reference "Expression profiling of genes related to starch synthesis in rice leaf sheaths during the heading period"

Reference ID

25471

Title

Expression profiling of genes related to starch synthesis in rice leaf sheaths during the heading period

Source

Physiologia Plantarum, 2006, vol. 128, pp. 425-435

Authors (4)

Hirose-T	Ohdan-T
Nakamura-Y	Terao-T

Abstract

The stems (leaf sheaths and culms) of rice plants (Oryza sativa L.) accumulate
high levels of starch before heading, which is subsequently remobilized after
heading to provide a carbon source for grain filling. To elucidate the molecular
mechanism of starch synthesis in rice leaf sheath, a comprehensive expression
analysis was conducted on the gene families encoding starch synthesis-related
enzymes, ADP-glucose pyrophosphorylase (EC 2.7.7.27), starch synthase (EC
2.4.1.21) and branching enzyme (EC 2.4.1.18). The changes in the activities of
these enzymes in leaf sheaths during the heading period were shown to be
accompanied by a coordinated change in the transcript levels of particular
members of the corresponding gene families. A similar change before and after
heading was also found in the messenger RNA level of GPT2, one of the two genes
encoding for a plastidial glucose-6-phosphate/phosphate translocator, suggesting
that the capacity of both starch synthesis and its substrate import is under
coordinated transcriptional regulation. The members of the gene families
predominantly expressed in leaf sheaths are mostly different from those actively
expressed in the developing endosperm. The time course for the transcript level
of some of these genes appears to correlate to hexose level in the leaf sheaths,
suggesting that hexose levels may be a controlling factor in their expression.