Riemann Michael, Muller Axel, Korte Arthur, Furuya Masaki, Weiler Elmar W, Nick Peter
Biologisches Institut II, Albert-Ludwigs-Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Plant Physiol. 2003 Dec;133(4):1820-30. doi: 10.1104/pp.103.027490. Epub 2003 Nov 6.
The elongation of rice (Oryza sativa) coleoptiles is inhibited by light, and this photoinhibition was used to screen for mutants with impaired light response. In one of the isolated mutants, hebiba, coleoptile elongation was stimulated in the presence of red light, but inhibited in the dark. Light responses of endogenous indolyl-3-acetic acid and abscisic acid were identical between the wild type and the mutant. In contrast, the wild type showed a dramatic increase of jasmonate heralded by corresponding increases in the content of its precursor o-phytodienoic acid, whereas both compounds were not detectable in the mutant. The jasmonate response to wounding was also blocked in the mutant. The mutant phenotype was rescued by addition of exogenous methyl jasmonate and o-phytodienoic acid. Moreover, the expression of O. sativa 12-oxophytodienoic acid reductase, an early gene of jasmonic acid-synthesis, is induced by red light in the wild type, but not in the mutant. This evidence suggests a novel role for jasmonates in the light response of growth, and we discuss a cross-talk between jasmonate and auxin signaling. In addition, hebiba represents the first rice mutant in which the induction of the jasmonate pathway is impaired providing a valuable tool to study the role of jasmonates in Graminean development.
水稻（Oryza sativa）胚芽鞘的伸长受到光照的抑制，利用这种光抑制作用筛选光反应受损的突变体。在分离出的一个突变体hebiba中，胚芽鞘伸长在红光存在下受到刺激，但在黑暗中受到抑制。野生型和突变体中内源吲哚-3-乙酸和脱落酸的光反应相同。相比之下，野生型中茉莉酸的含量显著增加，其前体邻-植物二烯酸的含量也相应增加，而在突变体中这两种化合物均无法检测到。突变体对创伤的茉莉酸反应也受到阻碍。通过添加外源茉莉酸甲酯和邻-植物二烯酸可挽救突变体的表型。此外，水稻12-氧植物二烯酸还原酶（茉莉酸合成的早期基因）的表达在野生型中受红光诱导，但在突变体中不受诱导。这一证据表明茉莉酸在生长的光反应中具有新的作用，我们还讨论了茉莉酸与生长素信号之间的相互作用。此外，hebiba是第一个茉莉酸途径诱导受损的水稻突变体，为研究茉莉酸在禾本科植物发育中的作用提供了有价值的工具。
