一个辣椒倍半萜环化酶cDNA克隆及其经紫外线和CuCl2处理后的表达特征

从经紫外线处理的辣椒（Capsicum annuum)叶片mRNA建立的cDNA库中筛选出1个长度为1955bp的克隆，SCCCA＃2。该cDNA编码560个氨基酸的蛋白，与SCCCA＃1分别有80．0％和77．2％的核苷酸和推测氨基酸序列同源性，但在3′非翻译区核苷酸同源性很小，此外，还与烟草的TEAS，天仙子的CVS，辣椒的EAS（can5588),番茄的germacrene合成酶基因，棉花的（＋）-delta-cadinene合成酶基因等倍半萜环化酶基因分别有78．0％，71．6％，74．8％，74．6％，40．0％－50．0％的氨基酸序列同源，认为这是1个辣椒倍半萜环化酶的cDNA，Northern blot分析表明，正常情况下SCCCA＃2在辣椒叶片中不表达，而在紫外线，CuCl2作用下有不同程度的表达。

A cDNA Clone of Sesquiterpens Cyclase from Capsicum annuum and Its Expression Under UV and CuCl2 Treatments

A cDNA clone,SCCCA#2,was isolated from the cDNA library established from mRNA of UV-treated pepper leaves(Capsicum annuum).It turned out to be a full-length cDNA of 1955bp with an open reading frame of560amino acids.The cDNA shared80.0%and77.2%homologies in nucleotide and deduced amino acid sequence with SCCCA#1,one of sesquiterpene cyclase cD NA clone isolated from the same library.It also shared78.0%,71.6%,74.8%,74.6%,40.0%~50.0%amino acid sequence identities with sesquiterpene cyclases of TEAS,CVS,EAS(can5588)of pepper,germacrene synthase of tomato,and(+)-delta-cadinene synthase of cotton,respectively.The results implicated that it was a sesquiterpene cyclase cDNA of Capsicum annuum.Northern blot analysis indicated that SCCCA#2was not expressed in the healthy pepper leaves,but to some degree in the pepper leaves under the treatment of UV radiation and CuCl 2 .