cDNA Cloning and Characterization of Gibberellin-Responsive Genes in Photoblastic Lettuce Seeds

通过差异筛选，从光胚莴苣（LactucasativaL.cv.大急流城）种子中分离到两个对赤霉素（GA）反应的cDNA克隆cLRG5和cLRG11。北方印迹分析表明，LRG 5和LRG 11 mRNA的水平在GA处理开始后10 h升高到略高的水平，并至少维持8 h，而对照种子中的水平逐渐下降。红光照射的效果与GA处理相似。还表明，由GA或红光处理引起的LRG5和LRG11 mRNA水平的增加不受完全抑制种子萌发的脱落酸（10 μ M）处理的影响<-4>。cLRG5插入片段编码380个氨基酸的推定多肽，其与来自几种高等植物的醇脱氢酶高度同源。关于cLRG11插入片段，尚未报道同源基因。为了研究LRG5和LRG11 mRNA在萌发的Grand Rapid种子中的定位，正在进行与核心cDNA的原位杂交。

Two cDNA clones, cLRG5 and cLRG11, that respond to gibberellin (GA) were isolated from seeds of photoblastic lettuce (Lactuca sativa L.cv.Grand Rapids) by differential screening. Northern Blot analysis indicated that the levels of LRG5 and LRG11 mRNAs were raised to slightly higher levels 10h after the start of GA treatment and the levels were maintained at least for further 8h, while those in the control seeds gradually decreased. Red light irradiation had effects similar to GA treatment. It was also shown that the increase of levels of LRG5 and LRG11 mRNAs caused by GA or red light treatment was not affected by treatment of abscisic acid (10^<-4> M) that inhibited the seed germination completely. The cLRG5 insert encodes a putative polypeptide of 380 amino acids that is highly homologous to alcohol dehydrogenases from several higher plants. With regard to the cLRG11 insert, no homologous gene has been reported. To investigatin of localization of LRG5 and LRG11 mRNAs in germinating Grand Rapid seeds, in situ hybridization with the coresoponding cDNAs are underway.