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Summary: Tissue-Preferential Expression of a Rice -Tubulin Gene,
OsTubA1, Mediated by the First Intron1
Jong-Seong Jeon, Sichul Lee, Ki-Hong Jung, Sung-Hoon Jun, Chanhong Kim, and Gynheung An*
Department of Life Science and National Research Laboratory of Plant Functional Genomics, Division of
Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790784,
Republic of Korea
The genomic clone encoding an -tubulin, OsTubA1, has been isolated from rice (Oryza sativa L.). The gene consists of four
exons and three introns. RNA-blot analysis showed that the gene is strongly expressed in actively dividing tissues, including
root tips, young leaves, and young flowers. Analysis of chimeric fusions between OsTubA1 and -glucuronidase (GUS)
revealed that the intron 1 was required for high-level GUS expression in actively dividing tissues, corresponding with
normal expression pattern of OsTubA1. Fusion constructs lacking the intron 1 showed more GUS staining in mature tissues
rather than young tissues. When the intron 1 was placed at the distal region from 5 -upstream region or at the 3 -
untranslated region, no enhancement of GUS expression was observed. Sequential deletions of the OsTubA1 intron 1 brought
about a gradual reduction of GUS activity in calli. These results suggest that tissue-preferential expression of the OsTubA1
gene is mediated by the intron 1 and that it may be involved in a mechanism for an efficient RNA splicing that is position
dependent.
Microtubules are the basis of morphogenetic pro-
cesses that occur by the definition of the plane of cell
division and the direction of cell elongation in plant
cells. Microtubules are mainly composed of - and
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