Os01g0201600

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Annotated Information

Function

• Gibberellins (GAs) are a class of phytohormones that regulate many aspects of plant growth and development processes including stem elongation,flowering, and seed germination.
• OsGAE1 is involved in various GAregulated developmental processes such as leaf sheath elongation, heading, and panicle development in rice.Elucidating the exact functions of OsGAE1 will contribute to understanding of GA action and the regulation of stem elongation and flower development in rice.

Expression

• To study the hormonal and temporal expression patterns of OsGAE1 mRNA, expression was analyzed in response to different hormones during development.The effect of several plant hormones was examined on OsGAE1 mRNA abundance (Fig. 3A). The basal parts of rice seedlings were incubated with 5 lM each GA3,IAA, ABA, and 1 lM BL for 24 h. It was observed that GA3 up regulated the expression of OsGAE1 while there was little effect of other hormones such as BL, IAA, and ABA. GA dose-dependent expression patterns were determined in rice leaf sheaths. OsGAE1 expression was up-regulated with the increase in GA3 concentration and it continued to increase up to concentration of 50 lM GA3 (Fig. 3B). During temporal gene expression, OsGAE1 mRNA accumulation in leaf sheath segments increased with GA3 as its expression was up-regulated starting from 1 h and this effect was observed at 24 h as well (Fig. 3C). For more careful analysis, reverse transcription-PCR (RT-PCR) was used to examine GA time-dependent expression of OsGAE1. OsGAE1-specific oligonucleotides were used to amplify transcripts from total RNA isolated from leaf sheath segments treated with 5 lM GA3 for 0, 10, 30, 60, and 180 min. The expression of OsGAE1 increased starting from 10 min and continued to increase till 180 min (Fig. 3D).

'Fig. 3 Hormonal-regulated expression of OsGAE1 in rice leaf sheath. (A) Effect of different phytohormones. Leaf sheath segments of 2-week-old seedlings were treated with 5 lM each GA3, IAA, ABA, and 1 lM BL for 24 h. (B) Dose-dependent effect of GA3. Leaf sheath segments were treated with or without 1, 5, 10, and 50 lM GA3 for 24 h. (C) Time course effect of GA3 treatment. Leaf sheath segments were treated with or without 5 lM GA3 for 1, 3, 6, 12, and 24 h. Total RNA (20 lg) was extracted from leaf sheath segments, transferred onto nylon membrane, and probed with the OsGAE1 cDNA. (D) RT-PCR analysis of GA time-dependent expression of OsGAE1. OsGAE1-specific oligonucleotides were used to amplify transcripts from total RNA isolated from leaf sheath segments treated with 5 lM GA3 for 0, 10, 30, 60, and 120 min. Actin was used as a control'

'Fig. 4 Organ- and tissue-specific expression of OsGAE1. (A)Organ-specific expression of OsGAE1 analyzed by Northern blot. Two-week-old rice seedlings and callus were treated with or without 5 lM GA3 for 24 h. Total RNA (20 lg) was extracted from root, leaf sheath, leaf blade, and callus, transferred onto nylon membrane, and probed with the OsGAE1 cDNA. (B)Tissue-specific expression of OsGAE1 by in situ hybridization.Sections were probe hybridized with Dig-labeled antisense OsGAE1 RNA (right). Dig-labeled sense OsGAE1 RNA was used as negative control (left). VB vascular bundles, SAM shoot apex meristem, PL primary leaf. Bar represents 500 lm'

• In order to examine the organ-specific expression of OsGAE1,total RNAs from rice callus, root, leaf blade, and leaf sheath were hybridized with OsGAE1-specific cDNA probe. A strong signal was detected in leaf sheath and callus but weak signal was observed in leaf blade, and root. Moreover, OsGAE1 expression in leaf sheath was increased when rice seedlings were treated with 5 lM GA3 for 24 h (Fig. 4A).In situ hybridization was performed using basal part of rice seedlings to learn more about the expression pattern. Hybridization of the longitudinal sections of rice basal part with gene-specific OsGAE1 antisense probe revealed the expression of OsGAE1 delimited to specific cell types, though significant hybridization was detected in shoot apex meristem region, young primary leaves, and vascular bundles (Fig. 4B, right). No significant signal was visible when sense probe of OsGAE1 was used (Fig. 4B, left).

Labs working on this gene

• Department of Molecular Biology, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba 305-8602, Japan
• Institute of Applied Biochemistry, School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
• National Institute of Crop Science, 2-1-18 Kannondai,Tsukuba 305-8518, Japan

References

• Abe M, Takahashi T, Komeda Y (1999) Cloning and characterization of an L1 layer-specific gene in Arabidopsis thaliana. Plant Cell Physiol 40:571–580