白鸡冠茶树CsPPH基因全长cDNA克隆与表达分析

脱镁叶绿素酶（Pheophytinase,PPH）是叶绿素降解过程中的一个关键酶,它能使脱镁叶绿素a转化为脱镁叶绿酸a,脱镁叶绿酸a是叶绿素降解途径中最后一个保持植物绿色的产物,被认为是叶片衰老和黄化的关键步骤。以新梢白化茶树白鸡冠叶片为材料,克隆获得CsPPH基因cDNA的全长序列（登录号：MK359094）,并对其进行生物信息学分析。结果表明,CsPPH全长为1 298 bp,包含的ORF序列为1 241 bp,编码413个氨基酸。序列分析表明,该基因编码的蛋白质为稳定疏水蛋白,其预测分子量为45 741.50 Da,理论等电点为6.12。预测该基因主要定位于叶绿体中。qRT-PCR结果显示,遮荫抑制白鸡冠叶片CsPPH的表达,叶绿素升高,叶色变绿;光照促进白鸡冠叶片CsPPH的表达,叶绿素降解,导致叶片白化。

Cloning and Expression Analysis of CsPPH Gene in Tea Plant (Camellia sinensis)

Pheophytinase (PPH) is a key enzyme in chlorophyll degradation. It can convert pheophytin a into pheophorbide a, which is the last product to keep green in chlorophyll degradation pathway. This step is considered to be a key step of leaf senescence and yellowing. In this study, the full-length sequence of CsPPH gene was cloned from the new shoot leaves of albino tea plant Camellia sinensis cv. Baijiguan (MK359094), and its biological characteristics were analyzed. The full-length of CsPPH was 1 298 bp, and the ORF was 1 241 bp, encoding 413 amino acids. Sequence analysis indicated that the encoded protein was a stable hydrophobic protein, and its molecular weight was predicted to be 45 741.50 Da. Its theoretical isoelectric point was 6.12. It was mainly located in chloroplasts. The real-time fluorescence quantitative PCR showed that under shading conditions, the expression of CsPPH was inhibited, chlorophyll increased and leaf color turned green. Light promoted the expression of CsPPH in leaves of cv. Baijiguan, and chlorophyll degradation led to leaf albinism.