Tomoko Kaneyasu

Publications (3)13.58 Total impact

• Article: GNOM-mediated vesicular trafficking plays an essential role in hydrotropism of Arabidopsis roots.

  Yutaka Miyazawa, Akiko Takahashi, Akie Kobayashi, Tomoko Kaneyasu, Nobuharu Fujii, Hideyuki Takahashi
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  ABSTRACT: Roots respond not only to gravity but also to moisture gradient by displaying gravitropism and hydrotropism, respectively, to control their growth orientation, which helps plants obtain water and become established in the terrestrial environment. As gravitropism often interferes with hydrotropism, however, the mechanisms of how roots display hydrotropism and differentiate it from gravitropism are not understood. We previously reported MIZU-KUSSEI1 (MIZ1) as a gene required for hydrotropism but not for gravitropism, although the function of its protein was not known. Here, we found that a mutation of GNOM encoding guanine-nucleotide exchange factor for ADP-ribosylation factor-type G proteins was responsible for the ahydrotropism of Arabidopsis (Arabidopsis thaliana), miz2. Unlike other gnom alleles, miz2 showed no apparent morphological defects or reduced gravitropism. Instead, brefeldin A (BFA) treatment inhibited both hydrotropism and gravitropism in Arabidopsis roots. In addition, a BFA-resistant GNOM variant, GNM696L, showed normal hydrotropic response in the presence of BFA. Furthermore, a weak gnom allele, gnomB/E, showed defect in hydrotropic response. These results indicate that GNOM-mediated vesicular trafficking plays an essential role in hydrotropism of seedling roots.
  Plant physiology 01/2009; 149(2):835-40. · 6.53 Impact Factor
• Article: Effects of locally targeted heavy-ion and laser microbeam on root hydrotropism in Arabidopsis thaliana.

  Yutaka Miyazawa, Tetsuya Sakashita, Tomoo Funayama, Nobuyuki Hamada, Hiroshi Negishi, Akie Kobayashi, Tomoko Kaneyasu, Atsushi Ooba, Keita Morohashi, Takehiko Kakizaki, Seiichi Wada, Yasuhiko Kobayashi, Nobuharu Fujii, Hideyuki Takahashi
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  ABSTRACT: Classical studies on root hydrotropism have hypothesized the importance of columella cells as well as the de novo gene expression, such as auxin-inducible gene, at the elongation zone in hydrotropism; however, there has been no confirmation that columella cells or auxin-mediated signaling in the elongation zone are necessary for hydrotropism. We examined the role of root cap and elongation zone cells in root hydrotropism using heavy-ion and laser microbeam. Heavy-ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy-ion broad-beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene, but not MIZU-KUSSEI1 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
  Journal of Radiation Research 08/2008; 49(4):373-9. · 1.68 Impact Factor
• Article: Auxin response, but not its polar transport, plays a role in hydrotropism of Arabidopsis roots.

  Tomoko Kaneyasu, Akie Kobayashi, Mayumi Nakayama, Nobuharu Fujii, Hideyuki Takahashi, Yutaka Miyazawa
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  ABSTRACT: Plants are sessile in nature, and need to detect and respond to many environmental cues in order to regulate their growth and orientation. Indeed, plants sense numerous environmental cues and respond via appropriate tropisms, and it is widely accepted that auxin plays an important role in these responses. Recent analyses using Arabidopsis have emphasized the importance of polar auxin transport and differential auxin responses to gravitropism. Even so, the involvement of auxin in hydrotropism remains unclear. To clarify whether or not auxin is involved in the hydrotropic response, Arabidopsis seedlings were treated with inhibitors of auxin influx (3-chloro-4-hydroxyphenylacetic acid), efflux (1-naphthylphthalemic acid and 2,3,5-triiodobenzoic acid), and response (p-chlorophenoxyisobutylacetic acid), and their effects were examined on both hydrotropic and gravitropic responses. In agreement with previous reports, gravitropism was inhibited by all the chemicals tested. By contrast, only an inhibitor of the auxin response (p-chlorophenoxyisobutylacetic acid) reduced hydrotropism, whereas inhibitors for influx or efflux of auxin had no effect. These results suggest that auxin response, apart from its polar transport, plays a definite role in hydrotropic response, and will evoke a new concept for the auxin-mediated regulation of tropisms.
  Journal of Experimental Botany 02/2007; 58(5):1143-50. · 5.36 Impact Factor