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

利用Poly-T引物，从荷兰鸢尾‘Blue Magic’鳞茎茎尖提取rna进行转录，并通过PCR扩增cdna。用恭敬显示法分析基因表达，将PCR产物在琼脂糖凝胶上电泳。在未施用乙烯的小球茎（9g）的茎尖上特异检测到PCR产物CG-01，认为该球茎处于幼苗期，对诱导冷却不敏感。研究的重点是该基因片段。在1999年将球茎暴露于高温之前，CG-01在小球茎中表达强烈，在大球茎（17g）中表达轻微。而CG-01的表达在100ppm乙烯处理24小时后消失。低温处理后，未施用乙烯的小球茎和大球茎的开花率分别为0%和33%，说明大部分或全部球茎处于幼期。利用高温处理后的球茎，用3′race法分析了CG-01的3′端DNA序列。用该接头引物和与CG-01序列相适应的合成引物扩增出PCR产物。然而，该PCR产物与已知的CG-01序列不同源。这些结果表明，CG-01在幼嫩期小鳞茎中的表达在夏季后消失。

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.