Wageningen University and Research Centre, Agrotechnology and Food Sciences Group, 6700 AA Wageningen, The Netherlands.
J Plant Physiol. 2012 Sep 15;169(14):1425-9. doi: 10.1016/j.jplph.2012.05.012. Epub 2012 Jul 4.
The floral buds of Iris flowers (Iris x hollandica) are enclosed by two sheath leaves. Flower opening depends on lifting the flower up to a position whereby the tepals can move laterally. This upward movement is carried out by elongation of the subtending pedicel and ovary. In the pedicels and ovaries of unstressed control flowers, the concentration of ACC (1-aminocyclopropane-1-carboxylic acid) and the rate of ethylene production increased during d 0-1 of flower opening, and then decreased. Exposure to ≥200 nL L(-1) ethylene for 24 h at 20°C inhibited elongation of the pedicel+ovary, and inhibited flower opening. However, pulsing of unstressed flowers with solutions containing inhibitors of ethylene synthesis (AOA, AVG), or an inhibitor of ethylene action (STS), did not affect pedicel+ovary elongation or flower opening. When the flowers were dehydrated for 2 d at 20°C and 60% RH, they did not open when subsequently placed in water, and showed inhibited elongation in the pedicel+ovary. This dehydration treatment resulted in elevated pedicel+ovary ACC levels and in increased ethylene production. Treatment with STS prevented the increase in ACC levels and ethylene production, overcame the effect of dehydration on elongation of the pedicel+ovary, and resulted in full flower opening. It is concluded that flower opening in unstressed Iris flowers is not regulated by endogenous ethylene. An increase in endogenous ethylene above normal levels during stress, by contrast, strongly inhibited flower opening, due to its inhibitory effect on elongation of the pedicel+ovary.
鸢尾花（Iris x hollandica）的花芽被两片鞘状叶片包裹。花朵开放取决于将花朵向上提起，使花瓣能够侧向移动。这种向上运动是由花梗和子房的伸长来完成的。在未受胁迫的对照花朵的花梗和子房内，ACC（1-氨基环丙烷-1-羧酸）浓度和乙烯生成率在开花前 0-1 天增加，然后降低。在 20°C 下，将花朵暴露于≥200 nL L（-1）的乙烯中 24 小时，会抑制花梗+子房的伸长，并抑制花朵开放。然而，用含有乙烯合成抑制剂（AOA、AVG）或乙烯作用抑制剂（STS）的溶液对未受胁迫的花朵进行脉冲处理，不会影响花梗+子房的伸长或花朵开放。当花朵在 20°C 和 60%相对湿度下脱水 2 天时，它们随后放入水中不会开放，并且花梗+子房的伸长受到抑制。这种脱水处理导致花梗+子房 ACC 水平升高和乙烯生成增加。STS 的处理阻止了 ACC 水平和乙烯生成的增加，克服了脱水对花梗+子房伸长的影响，导致花朵完全开放。因此，未受胁迫的鸢尾花的开花不受内源性乙烯的调节。相比之下，在胁迫期间，内源乙烯水平升高到正常水平以上，强烈抑制了花朵开放，这是由于其对花梗+子房伸长的抑制作用。
