Gianinetti Alberto, Laarhoven Lucas J J, Persijn Stefan T, Harren Frans J M, Petruzzelli Luciana
CRA-Experimental Institute for Cereal Research, Section of Fiorenzuola, s.s. via S. Protaso 302, 29017 Fiorenzuola d'Arda (PC), Italy.
Ann Bot. 2007 Apr;99(4):735-45. doi: 10.1093/aob/mcm008. Epub 2007 Mar 8.
The relationship between ethylene production and both seed dormancy and germination was investigated using red rice (weedy rice) as a model species.
Both fully dormant and after-ripened (non-dormant) naked caryopses were incubated with or without inhibitors of ethylene synthesis [aminoethoxyvinylglycine (AVG)] and perception [silver thiosulfate (STS)], or in the presence of the natural ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). The kinetics of ethylene emissions were measured with a sensitive laser-photoacoustic system.
Dormant red rice caryopses did not produce ethylene. In non-dormant caryopses, ethylene evolution never preceded the first visible stage of germination (pericarp splitting), and ethylene inhibitors completely blocked ethylene production, but not pericarp splitting. Accordingly, endogenous ACC appeared to be lacking before pericarp splitting. However, early seedling growth (radicle or coleoptile attaining the length of 1 mm) followed ethylene evolution and was delayed by the inhibitors. Wounding the dormant caryopses induced them to germinate and produce ethylene, but their germination was slow and pericarp splitting could be speeded up by ethylene.
The findings suggest that, in red rice, endogenous ethylene stimulates the growth of the nascent seedling, but does not affect seed dormancy or germination inception. Correspondingly, this phytohormone does not play a role in the dormancy breakage induced by wounding, but accelerates germination after such breakage has occurred.
以红米（杂草稻）为模式物种，研究乙烯产生与种子休眠及萌发之间的关系。
将完全休眠和后熟（非休眠）的裸颖果分别在有或无乙烯合成抑制剂[氨基乙氧基乙烯基甘氨酸（AVG）]和乙烯感知抑制剂[硫代硫酸银（STS）]的情况下进行培养，或在天然乙烯前体1-氨基环丙烷-1-羧酸（ACC）存在的条件下培养。用灵敏的激光光声系统测量乙烯释放的动力学。
休眠的红米颖果不产生乙烯。在非休眠颖果中，乙烯释放从未先于萌发的第一个可见阶段（果皮裂开），乙烯抑制剂完全阻断了乙烯的产生，但未阻断果皮裂开。因此，在果皮裂开之前似乎缺乏内源性ACC。然而，幼苗早期生长（胚根或胚芽达到1毫米长）跟随乙烯释放，并被抑制剂延迟。损伤休眠颖果可诱导其萌发并产生乙烯，但其萌发缓慢，乙烯可加速果皮裂开。
研究结果表明，在红米中，内源性乙烯刺激新生幼苗的生长，但不影响种子休眠或萌发起始。相应地，这种植物激素在伤口诱导的休眠破除中不起作用，但在休眠破除后加速萌发。
