Wilmowicz Emilia, Kesy Jacek, Kopcewicz Jan
Department of Physiology and Molecular Biology of Plants, Institute of General and Molecular Biology, Nicolaus Copernicus University, 9 Gagarina Street, 87-100 Torun, Poland.
J Plant Physiol. 2008 Dec;165(18):1917-28. doi: 10.1016/j.jplph.2008.04.009. Epub 2008 Jun 18.
Hormones are included in the essential elements that control the induction of flowering. Ethylene is thought to be a strong inhibitor of flowering in short day plants (SDPs), whereas the involvement of abscisic acid (ABA) in the regulation of flowering of plants is not well understood. The dual role of ABA in the photoperiodic flower induction of the SDP Pharbitis nil and the interaction between ABA and ethylene were examined in the present experiments. Application of ABA on the cotyledons during the inductive 16-h-long night inhibited flowering. However, ABA application on the cotyledons or the shoot apices during the subinductive 12-h-long night resulted in slight stimulation of flowering. Application of ABA also resulted in enhanced ethylene production. Whereas nordihydroguaiaretic acid (NDGA) - an ABA biosynthesis inhibitor - applied on the cotyledons of 5-d-old seedlings during the inductive night inhibited both the formation of axillary and of terminal flower buds, application of 2-aminoethoxyvinylglycine (AVG) and 2,5-norbornadiene (NBD) - inhibitors of ethylene action - reversed the inhibitory effect of ABA on flowering. ABA levels in the cotyledons of seedlings exposed to a 16-h-long inductive night markedly increased. Such an effect was not observed when the inductive night was interrupted with a 15-min-long red light pulse or when seedlings were treated at the same time with gaseous ethylene during the dark period. Lower levels of ABA were observed in seedlings treated with NDGA during the inductive night. These results may suggest that ABA plays an important role in the photoperiodic induction of flowering in P. nil seedlings, and that the inhibitory effect of ethylene on P. nil flowering inhibition may depend on its influence on the ABA level. A reversal of the inhibitory effect of ethylene on flower induction through a simultaneous treatment of induced seedlings with both ethylene and ABA strongly supports this hypothesis.
激素是控制开花诱导的基本要素之一。乙烯被认为是短日植物（SDPs）开花的强烈抑制剂，而脱落酸（ABA）在植物开花调控中的作用尚不清楚。本实验研究了ABA在SDP牵牛花光周期开花诱导中的双重作用以及ABA与乙烯之间的相互作用。在诱导性的16小时长夜期间，对子叶施用ABA会抑制开花。然而，在亚诱导性的12小时长夜期间，对子叶或茎尖施用ABA会导致开花略有增加。施用ABA还会导致乙烯产量增加。在诱导夜期间，将ABA生物合成抑制剂去甲二氢愈创木酸（NDGA）施用于5日龄幼苗的子叶上，会抑制腋芽和顶花芽的形成，而施用乙烯作用抑制剂2-氨基乙氧基乙烯基甘氨酸（AVG）和2,5-降冰片二烯（NBD）可逆转ABA对开花的抑制作用。暴露于16小时诱导夜的幼苗子叶中的ABA水平显著增加。当诱导夜被15分钟的红光脉冲打断或幼苗在黑暗期同时用气态乙烯处理时，未观察到这种效果。在诱导夜期间用NDGA处理的幼苗中观察到较低水平的ABA。这些结果可能表明，ABA在牵牛花子叶光周期开花诱导中起重要作用，乙烯对牵牛花开花的抑制作用可能取决于其对ABA水平的影响。通过同时用乙烯和ABA处理诱导的幼苗来逆转乙烯对花诱导的抑制作用，有力地支持了这一假设。
