5.キュウリ芽ばえの重力形態形成におけるオーキシン抑制遺伝子の発現解析(口頭発表)

概要

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Auxin is an important plant hormone for morphogenesis. Cucumber seedlings form a specialized protuberance, called peg, on the transition zone (TR-zone) between the hypocotyl and root. When cucumber seeds germinate in a horizontal position, seedlings develop a peg on the lower side of the TR-zone. We previously demonstrated that auxin was more abundant in the lower side than in the upper side of the gravistimulated TR-zone and suggested that this asymmetric auxin distribution induced differential auxin response to contribute to peg formation. Moreover, application of auxin or auxin-polar-transport inhibitor (TIBA) induced both expression of auxin-inducible gene expression and peg formation at both upper and lower side of the TR-zone, whereas application of anti-auxin (PCIB) induced neither. Recently, we found CsGRPl whose mRNA accumulated more abundantly in the upper side than in the lower side of the TR-zone. We found that this accumulation of CsGRPl mRNA was decreased by the application of either auxin or TIBA. On the other hand, application of PCIB induced CsGRPl gene expression in both upper and lower side of the TR-zone. These results suggest that gravistimulation increases not only the expression of auxin-inducible genes on the lower side of the TR-zone but also the expression of auxin-repressed genes, such as CsGRPl, on the upper side in cucumber seedlings to contribute to the one-sided formation of the peg.
2007-10-05