Reference "A Rice Semi-Dwarf Gene, Tan-Ginbozu ( D35 ), Encodes the Gibberellin Biosynthesis Enzyme, ent -Kaurene Oxidase"

Reference ID

8302

Title

A Rice Semi-Dwarf Gene, Tan-Ginbozu ( D35 ), Encodes the Gibberellin Biosynthesis Enzyme, ent -Kaurene Oxidase

Source

Plant molecular biology, 2004, vol. 54, pp. 533-547

Authors (9)

Itoh-H	Tatsumi-T
Sakamoto-T	Otomo-K
Toyomasu-T	Kitano-H
Ashikari-M	Ichihara-S
Matsuoka-M

Abstract

A rice ( Oryza sativa L.) semi-dwarf cultivar, Tan-Ginbozu ( d35 ( Tan-Ginbozu
)), contributed to the increase in crop productivity in Japan in the 1950s.
Previous studies suggested that the semi-dwarf stature of d35 ( Tan-Ginbozu ) is
caused by a defective early step of gibberellin biosynthesis, which is catalyzed
by ent -kaurene oxidase (KO). To study the molecular characteristics of d35 (
Tan-Ginbozu ), we isolated 5 KO-like ( KOL ) genes from the rice genome, which
encoded proteins highly homologous to Arabidopsis and pumpkin KOs. The genes (
OsKOL1 to 5 ) were arranged as tandem repeats in the same direction within a 120
kb sequence. Expression analysis revealed that OsKOL2 and OsKOL4 were actively
transcribed in various organs, while OsKOL1 and OsKOL5 were expressed only at
low levels; OsKOL3 may be a pseudogene. Sequence analysis and complementation
experiments demonstrated that OsKOL2 corresponds to D35. Homozygote with null
alleles of D35 showed a severe dwarf phenotype; therefore, d35 ( Tan-Ginbozu )
is a weak allele of D35. Introduction of OsKOL4 into d35 ( Tan-Ginbozu ) did not
rescue its dwarf phenotype, indicating that OsKOL4 is not involved in GA
biosynthesis. OsKOL4 and OsKOL5 are likely to take part in phytoalexin
biosynthesis, because their expression was promoted by UV irradiation and/or
elicitor treatment. Comparing d35 ( Tan-Ginbozu ) with other high yielding
cultivars, we discuss strategies to produce culm architectures suitable for high
crop yield by decreasing GA levels.