4. 高等植物の形態形成におけるオーキシン極性移動の重要性

概要

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Relationships between morphogenesis and auxin polar transport in etiolated pea (Pisum sativum L. cv. Alaska) seedlings were studied, especially in molecular levels. Activities of auxin polar transport in proximal side of epicotyls to cotyledons in etiolated pea seedlings were much higher than those in distal one. Accumulation of PsPIN1 mRNA was observed in proximal side of epicotyls to cotyledons, it showing a good correlation with activities of auxin polar transport. Exogenously applied TIBA (2, 3, 5-triiodobenzoic acid) induced automorphosis-like growth and development of etiolated pea seedlings which were found in microgravity conditions in space. In this case, expression of PsIAA4/5, one of auxin-inducible genes in pea seedlings, was extremely suppressed in proximal and distal sides of epicotyls to cotyledons. These results suggest that the activity of auxin polar transport and intercellular auxin level are essential factors to regulate morphogenesis of etiolated pea seedlings. Further studies on other PsPIN genes and MDR genes, which affect auxin polar transport in higher plants, will also be required.
2005-10-13