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

通过差异筛选，从光育莴苣（Lactuca sativa l.c.v grand Rapids）种子中分离到两个对赤霉素（gibberellin， GA）有应答的cDNA克隆cLRG5和cLRG11。Northern Blot分析表明，在GA处理开始后10h， LRG5和LRG11 mrna水平升高至略高水平，并至少维持8h，而对照种子的mrna水平逐渐下降。红光照射的效果与GA处理相似。赤霉素和红光处理导致的LRG5和LRG11 mrna水平升高不受完全抑制种子萌发的脱落酸（10^<-4> M）处理的影响。cLRG5插入物编码一种被认为含有380个氨基酸的多肽，与几种高等植物的乙醇脱氢酶高度同源。关于cLRG11插入物，没有同源基因的报道。为了研究大速种子萌发过程中LRG5和LRG11 mrna的定位，目前正在与相应的cdna进行原位杂交。

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.