宁夏枸杞苯丙氨酸解氨酶基因的cDNA克隆及其表达分析

Cloning and Expression Analysis of Phenylalanine Ammonia-lyase Gene from Lycium barbarum L.

摘要:

为探讨宁夏枸杞（Lycium barbarum）苯丙氨酸解氨酶基因（LbPAL）的表达特征，采用PCR 法克隆了宁夏枸杞LbPAL 基因的cDNA，并用实时定量PCR 法分析了其表达特征。结果表明：宁夏枸杞的LbPAL 基因的全长cDNA 为2321 bp，包含2163 bp、编码720 个氨基酸的开放阅读框；LbPAL 与茄科其他物种的PAL 氨基酸序列及三维结构具有较高保守性；与茄科物种的PAL 聚类在同一个分支中。LbPAL 在叶、花瓣、S1 期果实的表达量较高，而在根及S2 ~ S5 期果实的表达水平较低。在NaCl 胁迫处理下，LbPAL 在根和茎中的表达量均有下调的趋势；而在叶片中，LbPAL 表达量先急剧增加而后急剧下降并趋于稳定。这为解析宁夏枸杞中类黄酮化合物的生物合成调节及生理功能提供了参考。

关键词:宁夏枸杞;苯丙氨酸解氨酶基因;基因表达;盐胁迫

Abstract:

In order to understand the expression of phenylalanine ammonia-lyase gene from Lycium barbarum L., named as LbPAL, the cDNA of LbPAL was cloned using PCR and its expression was characterized. The results showed that the whole length of LbPAL cDNA was 2321 bp containing an open reading frame (ORF) of 2163 bp, encoding 720 amino acids. Amino acid sequence analysis indicated that LbPAL had high identity of sequence and similarly tertiary structure to PALs in other Solanaceae plants. Phylogenetic analysis demonstrated that LbPAL was clustered in the same clade with PALs in other Solanaceae plants. Real-time PCR analysis showed that LbPAL was highly expressed in leaves, petals and fruits at S1 stage, while few LbPAL transcripts were detected in roots and fruits at stages from S2 to S5. Under salt stress, LbPAL expression was downregulated in roots and stems, while sharply enhanced at 0.5 h and decreased hereafter in leaves. These results lay a foundation for elucidating the biosynthesis and physiological regulation of flavonoid in L. barbarum.

Key words:Lycium barbarum;Phenylalanine ammonia-lyase gene;Gene expression;Salt stress