Reference "Expression profiling of genes involved in starch synthesis in sink and source organs of rice"

Reference ID

11070

Title

Expression profiling of genes involved in starch synthesis in sink and source organs of rice

Source

Journal of experimental botany, 2005, vol. 56, pp. 3229-3244

Authors (6)

Ohdan-T	Sawada-T
Hirose-T	Terao-T
Satoh-H	Nakamura-Y

Abstract

A comprehensive analysis of the transcript levels of genes which encode starch-
synthesis enzymes is fundamental for the assessment of the function of each
enzyme and the regulatory mechanism for starch biosynthesis in source and sink
organs. Using quantitative real-time RT-PCR, an examination was made of the
expression profiles of 27 rice genes encoding six classes of enzymes, i.e.
ADPglucose pyrophosphorylase (AGPase), starch synthase, starch branching enzyme,
starch debranching enzyme, starch phosphorylase, and disproportionating enzyme
in developing seeds and leaves. The modes of gene expression were tissue- and
developmental stage-specific. Four patterns of expression in the seed were
identified: group 1 genes, which are expressed very early in grain formation and
are presumed to be involved in the construction of fundamental cell machineries,
de novo synthesis of glucan primers, and initiation of starch granules; group 2
genes, which are highly expressed throughout endosperm development; group 3
genes, which have transcripts that are low at the onset but which rise steeply
at the start of starch synthesis in the endosperm and are thought to play
essential roles in endosperm starch synthesis; and group 4 genes, which are
expressed scantly, mainly at the onset of grain development, and might be
involved in synthesis of starch in the pericarp. The methodology also revealed
that the defect in the cytosolic AGPase small subunit2b (AGPS2b) transcription
from the AGPS2 gene in endosperm sharply enhanced the expressions of endosperm
and leaf plastidial AGPS1, the endosperm cytosolic AGPase large subunit2
(AGPL2), and the leaf plastidial AGPL1.