Singh V, Singh B, Sharma A, Kaur K, Gupta A P, Salar R K, Hallan V, Pati P K
Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, India.
QC & QA, Indian Institute of Integrative Medicine, Jammu Tawi, Jammu and Kashmir, India.
J Appl Microbiol. 2017 Jan;122(1):153-165. doi: 10.1111/jam.13314. Epub 2016 Nov 15.
The present work investigates the implication of leaf spot disease on the antioxidant potential and commercial value of pharmaceutically important constituents of Withania somnifera, a high-valued medicinal plant.
Leaf spot disease was induced in W. somnifera by inoculating Alternaria alternata (Fr.) Keiss. pathogen. Total polyphenolic content and antioxidant potential showed a significant decrease during leaf spot disease. Evaluation of pharmaceutically active constituents withaferin A, withanone and withanolide A utilizing high-performance liquid chromatography showed a significant decrease in diseased samples as compared to healthy ones. Quantitative expression of major genes involved in withanolide biosynthesis also showed down-regulation in diseased samples. Alterations in the ultra-structure of chloroplasts were also analysed under transmission electron microscopy to get a better insight into the changes of withanolide biosynthesis in leaf during disease infestation.
The present work suggests that when the pathogenic fungus invades the host plants, it evokes multiple responses, which could be studied at various levels. The knowledge gained from this work will provide appropriate rationale for controlling the bio-deterioration of the pharmaceutically active metabolites in W. somnifera and development of suitable strategies against leaf spot disease.
This is the first study to investigate the effect of leaf spot disease on the human health-promoting constituents and withanolide biosynthesis in this high-valued medicinal plant.
本研究调查叶斑病对睡茄（一种高价值药用植物）抗氧化潜力及重要药用成分商业价值的影响。
通过接种链格孢（Alternaria alternata (Fr.) Keiss.）病原菌诱导睡茄发生叶斑病。叶斑病期间，总多酚含量和抗氧化潜力显著下降。利用高效液相色谱法对药用活性成分睡茄素A、睡茄酮和睡茄内酯A进行评估，结果显示，与健康样本相比，患病样本中的这些成分显著减少。参与睡茄内酯生物合成的主要基因的定量表达在患病样本中也呈下调。还通过透射电子显微镜分析了叶绿体超微结构的变化，以便更好地了解病害侵染期间叶片中睡茄内酯生物合成的变化。
本研究表明，当致病真菌侵入宿主植物时，会引发多种反应，可在多个层面进行研究。从这项研究中获得的知识将为控制睡茄中具有药用活性的代谢产物的生物劣化以及制定防治叶斑病的合适策略提供合理依据。
这是首次研究叶斑病对这种高价值药用植物中促进人类健康的成分及睡茄内酯生物合成的影响。
