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. 2004 Apr;134(4):1642-53.
doi: 10.1104/pp.103.033696. Epub 2004 Apr 9.

An overview of gibberellin metabolism enzyme genes and their related mutants in rice

Tomoaki Sakamoto  1 , Koutarou Miura, Hironori Itoh, Tomoko Tatsumi, Miyako Ueguchi-Tanaka, Kanako Ishiyama, Masatomo Kobayashi, Ganesh K Agrawal, Shin Takeda, Kiyomi Abe, Akio Miyao, Hirohiko Hirochika, Hidemi Kitano, Motoyuki Ashikari, Makoto Matsuoka
Affiliations

An overview of gibberellin metabolism enzyme genes and their related mutants in rice

Tomoaki Sakamoto et al. Plant Physiol. 2004 Apr.

Erratum in

  • Plant Physiol.2004 Jul;135(3):1863

Abstract

To enhance our understanding of GA metabolism in rice (Oryza sativa), we intensively screened and identified 29 candidate genes encoding the following GA metabolic enzymes using all available rice DNA databases: ent-copalyl diphosphate synthase (CPS), ent-kaurene synthase (KS), ent-kaurene oxidase (KO), ent-kaurenoic acid oxidase (KAO), GA 20-oxidase (GA20ox), GA 3-oxidase (GA3ox), and GA 2-oxidase (GA2ox). In contrast to the Arabidopsis genome, multiple CPS-like, KS-like, and KO-like genes were identified in the rice genome, most of which are contiguously arranged. We also identified 18 GA-deficient rice mutants at six different loci from rice mutant collections. Based on the mutant and expression analyses, we demonstrated that the enzymes catalyzing the early steps in the GA biosynthetic pathway (i.e. CPS, KS, KO, and KAO) are mainly encoded by single genes, while those for later steps (i.e. GA20ox, GA3ox, and GA2ox) are encoded by gene families. The remaining CPS-like, KS-like, and KO-like genes were likely to be involved in the biosynthesis of diterpene phytoalexins rather than GAs because the expression of two CPS-like and three KS-like genes (OsCPS2, OsCPS4, OsKS4, OsKS7, and OsKS8) were increased by UV irradiation, and four of these genes (OsCPS2, OsCPS4, OsKS4, and OsKS7) were also induced by an elicitor treatment.

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Figures

Figure 1.
Figure 1.
Principal pathway of GA metabolism in plants. GA13ox, GA 13-hydroxylase.
Figure 2.
Figure 2.
Chromosomal location of the candidate genes for GA metabolism and contiguous arrangement of CPS-like and KS-like genes. A, Map position of the candidate genes for GA metabolism on the rice genome. B to E, Contiguous arrangement of CPS-like and KS-like genes. CPS-like and KS-like genes are indicated by red arrows. Yellow and blue arrows indicate the genes encoding putative Cyt P450 and transposon-like sequences, respectively. White arrows show other predicted genes. The orientation of each gene is indicated by the direction of the arrow. The gene prediction was performed using the RiceGAAS program (http://ricegaas.dna.affrc.go.jp/), alignment with expressed sequence tag sequences, and direct sequence analysis of RT-PCR products. Intergenic regions are drawn to scale and contain no other genes.
Figure 3.
Figure 3.
Phylogenetic relationships among GA metabolic diterpene cyclases, CPS and KS (A), GA metabolic Cyt P450-dependent monooxygenases KO and KAO (B), and GA metabolic 2ODDs GA20ox, GA3ox, and GA2ox (C). At, Arabidopsis; Cm, pumpkin; Cs, Cucumis sativus; Hv, barley; Le, tomato; Ls, lettuce; Pc, Phaseolus coccineus; Ps, pea; Sd, Scoparia dulcis; Sr, Stevia rebaudiana; and Zm, maize.
Figure 4.
Figure 4.
Typical phenotype of GA-deficient rice dwarf mutants (A) and rescue of the dwarf phenotype by external GA3 treatment (B). We used three criteria for screening of the GA-deficient mutants, that is, dwarfism without aberrant morphology, dark green leaves, and restoration of dwarfism to the wild type by the GA3 treatment.
Figure 5.
Figure 5.
Phenotypes of rice GA-deficient dwarf mutants. A, Comparison of gross morphology between mutant plants and their original cultivars. 1, Nipponbare (original strain for oscps-1, osks1-1, osko2-1, and oskao-1); 2, oscps-1 (null allele); 3, osks1-1 (null allele); 4, Ginbozu (original strain for osko2-2); 5, osko2-2 (weak allele); 6, osko2-1 (null allele); 7, oskao-1 (null allele); 8, Woo-gen (original strain for sd1-1); 9, sd1-1 (null allele); 10, Akibare (original strain for d18-AD); 11, d18-dy (weak allele); and 12, d18-AD (null allele). B to F, Close-up view of oscps-1, osks1-1, osko2-1, oskao-1, and d18-AD, respectively. Arrows indicate panicles containing fertile seeds. Bar represents 5 cm.
Figure 6.
Figure 6.
Genomic structure of the GA metabolic genes. Boxes and lines indicate exons and introns, respectively. The mutation sites are indicated below each line. Arrowheads indicate the insertion sites of a rice retrotransposon, Tos17. Nucleotide substitutions producing amino acid exchanges are indicated by X numeral Y (X, amino acid residue in the wild-type allele; numeral, the position of exchanged amino acid residue; Y, amino acid residue in the mutant allele).
Figure 7.
Figure 7.
Expression of the GA metabolic genes in various organs of the wild-type rice. Total RNAs were isolated from vegetative shoot apices (1), leaf sheaths (2), leaf blades (3), stems (4), roots (5), immature panicles (6), and panicles at flowering time (7), and quantitative RT-PCR was conducted (see “Materials and Methods”). Histone H3 was used as a control.
Figure 8.
Figure 8.
Effect of UV irradiation and elicitor treatment on the levels of CPS-like and KS-like gene expression. Left, Comparison between UV irradiated for 30 min (+) and nonirradiated (−) wild-type seedlings. Right, Cultured cells of wild-type rice were harvested at 0, 1, 2, 3, 6, and 12 h after the elicitor treatment. Experiments were performed as in Figure 7. No PCR product was detected from RNA isolated from cultured cells using the combination of primers for OsCPS1, OsKS1, OsKS6, or OsKS8. Histone H3 was used as a control.
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