Abstract
Main conclusion
The leaves of Withania somnifera contained four morphologically distinct trichome types: glandular capitate, non-glandular dendritic (branched), non-glandular bicellular and non-glandular multicellular trichomes. Major phytochemical compounds present within glandular and non-glandular trichomes were alkaloids and phenolic compounds.
The aim of this study was to characterize the micromorphology of the foliar trichomes of Withania somnifera as well as to elucidate the location and composition of the secretory products. Trichome density and length was also determined in three developmental stages of the leaves. Light microscopy and scanning electron microscopy showed the presence of four morphologically distinct trichome types: glandular capitate, non-glandular dendritic, non-glandular bicellular and non-glandular multicellular. The dendritic trichomes exhibited cuticular warts which are involved in the “Lotus-Effect”. Glandular capitate and non-glandular dendritic trichomes were aggregated on the mid-vein of young and mature leaves, possibly to protect underlying vasculature. Histochemical staining also revealed the presence of two major classes of phytochemical compounds that are of medicinal importance, i.e. alkaloids and phenolic compounds. These compounds are used to treat a wide variety of ailments and also act as chemical deterrents in plants. The results of this study explain possible roles of four morphologically distinct trichome types based on their morphology, foliar distribution and content.
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Acknowledgments
The authors would like to thank Preyan Arumugam, Kashmira Raghu and Ashlin Munsamy for research assistance and aiding with histochemical preparation. Drs S. Gairola and C.T. Sadashiva are thanked for editing the manuscript and assistance with phytochemical and TLC studies, respectively. Funding from the National Research Foundation (NRF) is also gratefully appreciated.
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Munien, P., Naidoo, Y. & Naidoo, G. Micromorphology, histochemistry and ultrastructure of the foliar trichomes of Withania somnifera (L.) Dunal (Solanaceae). Planta 242, 1107–1122 (2015). https://doi.org/10.1007/s00425-015-2341-1
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DOI: https://doi.org/10.1007/s00425-015-2341-1