Shukla Ashutosh K, Shasany Ajit K, Gupta Madan M, Khanuja Suman P S
Genetic Resources and Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India.
J Exp Bot. 2006;57(14):3921-32. doi: 10.1093/jxb/erl146. Epub 2006 Oct 18.
In Catharanthus roseus (L.) G. Don each tissue is known to produce a distinct spectrum of terpenoid indole alkaloids. Since the invaluable antineoplastic bisindole alkaloids are restricted to the aerial parts of the plant and do not occur in its underground tissues, identification of the structural and regulatory factors operating distinctly in the shoot/leaf of the plant will be a necessity for modulation of bisindole alkaloid biosynthesis. This study aimed at elucidating the differential gene expression in the two main tissues (leaf and root) of the plant, well known for their distinct terpenoid indole alkaloid profiles. The leaf and root transcriptomes of C. roseus were comparatively analysed using two different approaches: (i) indirectly through construction and characterization of separate cDNA libraries; and (ii) directly through a strategically designed suppression subtractive hybridization, using the leaf and root cDNA populations as tester and driver, respectively. A total of 155 ESTs (55 and 45 from the separate leaf and root cDNA libraries, respectively, and 55 from the subtracted leaf-specific cDNA library) were subjected to homology-based classification and submitted to dbEST. The direct approach yielded an EST for sgd (strictosidine beta-D-glucosidase) and 16 novel ESTs. Dat (acetyl-CoA: 4-O-deacetylvindoline 4-O-acetyl-transferase) and sgd transcripts could not be detected in the root system of the plant (cv. 'Dhawal') at any developmental stage (6 d, 6 weeks, or 6 months). The growth-related decrease in shoot/leaf dat and sgd transcript levels was paralleled by a concomitant decrease in shoot/leaf vindoline content.
在长春花中，已知每个组织都会产生独特的萜类吲哚生物碱谱。由于极为珍贵的抗肿瘤双吲哚生物碱仅限于植物的地上部分，而不存在于其地下组织中，因此鉴定在植物地上部分/叶片中特异性发挥作用的结构和调控因子对于调节双吲哚生物碱的生物合成至关重要。本研究旨在阐明该植物两个主要组织（叶和根）中差异基因的表达情况，这两个组织以其独特的萜类吲哚生物碱谱而闻名。采用两种不同方法对长春花的叶和根转录组进行了比较分析：（i）通过构建和表征单独的cDNA文库间接进行；（ii）通过策略性设计的抑制性消减杂交直接进行，分别以叶和根的cDNA群体作为测试方和驱动方。总共155条EST（分别来自单独的叶和根cDNA文库的55条和45条，以及来自消减后的叶特异性cDNA文库的55条）进行了基于同源性的分类，并提交至dbEST。直接方法产生了一条sgd（裂环马钱子苷β-D-葡萄糖苷酶）的EST和16条新的EST。在植物（品种‘Dhawal’）根系的任何发育阶段（6天、6周或6个月）均未检测到Dat（乙酰辅酶A：4-O-脱乙酰文朵灵4-O-乙酰转移酶）和sgd转录本。地上部分/叶片中Dat和sgd转录本水平随生长而下降，同时地上部分/叶片中文朵灵含量也随之下降。
