Expression of gene specific to ethylene-induced ripeness to flower in Dutch iris bulbs

利用Poly-T引物，从荷兰蝴蝶兰‘Blue Magic’鳞茎顶端提取的RNA中转录出cDNAs，并通过聚合酶链式反应进行扩增。用差异显示法分析基因表达，扩增产物在琼脂糖凝胶上电泳。在不施乙烯的小鳞茎(9G)顶端检测到一条特异的扩增产物(CG-01)，该产物被认为处于幼苗期，对诱导冷害不敏感。在1999年将鳞茎置于高温下之前，CG-01在小型鳞茎中表达强烈，而在大型鳞茎(17g)中表达较弱。然而，在100ppm的乙烯作用24小时后，CG-01的表达消失。不施乙烯处理后，小鳞茎开花率为0%，大鳞茎开花率为33%，表明全部或大部分鳞茎处于幼苗期。用3‘RACE方法对CG-01的3’端DNA序列进行了分析。用该适配子引物和与CG-01序列相匹配的合成引物扩增出一条扩增产物。然而，该聚合酶链式反应产物与已知的CG-01的序列不是同源的。这些结果表明，即使在幼虫期的小鳞茎中，CG-01的表达在夏季后也消失了。

Using Poly-T primers, cDNAs were transcripted from RNAs extracted from the shoot tip of Dutch iris 'Blue Magic' bulbs, and they were amplified through PCR. Gene expression was analyzed by deferential display method, electrophoresing these PCR products on agarose gel. A PCR product (namely CG-01) was detected specifically in shoot tip of small-size bulbs (9g) without ethylene application, which were considered to be in juvenile phase and insensitive to inductive chilling. Investigation was focusted on this gene fragment.Before exposing bulbs to high temperature in 1999, expression of CG-01 was detected strongly in small-size bulbs and slightly in large-size bulbs (17g). However, the expression of CG-01 disappeared after exposing them to 100ppm ethylene for 24 hr. The flowering percentage of small-size and large-size bulbs after chilling treatment were 0% and 33%, respectively, if ethylene was not applied, indicating that all or most of bulbs were at juvenile phase. DNA sequence of CG-01 toward the 3' terminal was analyzed by a 3'RACE method suing bulbs after exposing them to high temperature. A PCR product which was amplified by the adaptor primer and a synthetic primer adupted to CG-01 sequence was obtained. However, sequence of this PCR product and that of CG-01 already known was not homologous. These results indicated that expression of CG-01 disappeared after summer even in small size bulbs at juvenile phase.