Impact of exogenous nicotine on the morphological, physio-biochemical, and anatomical characteristics in Capsicum annuum

Abstract

Nicotine is an alkaloid which only highly exists in tobacco plants. It accounts for 95% of its total alkaloid content. Nicotine is synthesized in the roots and transported via the xylem to the shoot. This study aimed to investigate the morphological, physio-biochemical, structural, and ultrastructural impacts of different nicotine concentrations in bell pepper. Capsicum annuum seedlings were grown hydroponically in a growth chamber with different nicotine concentrations (0, 100, 400, 700, 1,000, 3,000, and 5,000 µM). Nicotine-treated leaves (3,000 and 5,000 µM) exhibited severe chlorosis and necrosis. Moreover, nicotine-treated seedlings (1,000, 3,000, and 5,000 µM) exhibited severe reduction in leaf area (p < 0.0001) and photosynthetic efficiency (p < 0.0001), which significantly reduce the photosynthetic rate (p < 0.0001). Also, the drop in the photosynthetic rate was associated with significant drop in stomatal conductance (p < 0.0001). The electron transmission micrographs revealed that nicotine-treated seedlings (3,000 and 5,000 µM) exhibited deformed chloroplasts with numerous plastoglobules reducing the photosynthetic rates.

Novelty statement

This is one of few studies that deal with the impact of exogenous nicotine on plants. However, to the best of our knowledge, this is the first hydroponic study that used liquid pure nicotine implied to the plants. The morphological, physio-biochemical, and anatomical characteristics were investigated using Capsicum annuum as a model plant, a plant that synthesizes little endogenous nicotine. This study will shed more light about nicotine toxicity in plants.

Keywords:

• Chloroplast
• nicotine
• photosynthetic rate
• starch grains
• xylem

Acknowledgments

Special thanks for Ms. Duaa Qattan and Kholoud Friehat for their TEM technical assistance, Faculty of Medicine, The University of Jordan, Amman, Jordan. The funding body had no role in the design of the study and no role in the collection, analysis, and interpretation of data or in writing the manuscript

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by the Deanship of Scientific Research at Jordan University of Science and Technology [grant No. 20170330].