Satler S O, Kende H
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1985 Sep;79(1):194-8. doi: 10.1104/pp.79.1.194.
Etiolated whole rice seedlings enclosed in sealed vials produced ethylene at a rate of 0.9 picomole per hour per seedling. When 2-centimeter-long shoots were subdivided into 5-millimeter-long sections, the sections containing the tip of the shoot evolved 37% of the total ethylene with the remaining 63% being produced along a gradient decreasing to the base of the shoot. The tip of the coleoptile also had the highest level of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and of the ethylene-forming enzyme activity. Ethylene is one of the factors controlling coleoptile elongation. Decapitation of the seedling reduced ethylene evolution to one-third its original level and inhibited coleoptile growth. In short-term experiments, the growth rate of decapitated seedlings was restored to almost that of intact seedlings by application of ethylene at a concentration of 10 microliters per liter. Apart from ethylene, O(2) also participates in the control of coleoptile growth. When rice seedlings were grown in a gas mixture of N(2) and O(2), the length of the coleoptiles reached a maximum at a concentration of 2.5% O(2). Lower and higher concentrations of O(2) reduced coleoptile growth. The effect of exogenous ethylene on coleoptile growth was also O(2) dependent.
封闭在密封小瓶中的黄化水稻幼苗以每株每小时0.9皮摩尔的速率产生乙烯。当将2厘米长的芽分成5毫米长的小段时，含有芽尖的小段释放出总乙烯量的37%，其余63%沿着向芽基部递减的梯度产生。胚芽鞘尖端的乙烯前体1-氨基环丙烷-1-羧酸水平和乙烯形成酶活性也最高。乙烯是控制胚芽鞘伸长的因素之一。去头的幼苗乙烯释放量降至原来水平的三分之一，并抑制了胚芽鞘的生长。在短期实验中，通过施加浓度为每升10微升的乙烯，去头幼苗的生长速率恢复到几乎与完整幼苗相同。除乙烯外，O₂也参与胚芽鞘生长的控制。当水稻幼苗在N₂和O₂的混合气体中生长时，胚芽鞘长度在O₂浓度为2.5%时达到最大值。较低和较高浓度的O₂都会降低胚芽鞘的生长。外源乙烯对胚芽鞘生长的影响也取决于O₂。
