pp 1–15 | Cite as

Interspecies comparative features of trichomes in Ocimum reveal insights for biosynthesis of specialized essential oil metabolites

  • Shiwani Maurya
  • Muktesh Chandra
  • Ritesh K. Yadav
  • Lokesh K. Narnoliya
  • Rajender S. Sangwan
  • Shilpi Bansal
  • Pankajpreet Sandhu
  • Umesh Singh
  • Devender Kumar
  • Neelam Singh SangwanEmail author
Original Article


Ocimum species commonly referred to as “Tulsi” are well-known for their distinct medicinal and aromatic properties. The characteristic aroma of Ocimum species and cultivars is attributed to their specific combination of volatile phytochemicals mainly belonging to terpenoid and/or phenylpropanoid classes in their essential oils. The essential oil constituents are synthesized and sequestered in specialized epidermal secretory structures called as glandular trichomes. In this comparative study, inter- and intra-species diversity in structural attributes and profiles of expression of selected genes related to terpenoid and phenylpropanoid biosynthetic pathways have been investigated. This is performed to seek relationship of variations in the yield and phytochemical composition of the essential oils. Microscopic analysis of trichomes of O. basilicum, O. gratissimum, O. kilimandscharicum, and O. tenuiflorum (green and purple cultivars) revealed substantial variations in density, size, and relative proportions of peltate and capitate trichomes among them. The essential oil yield has been observed to be controlled by the population, dominance, and size of peltate and capitate glandular trichomes. The essential oil sequestration in leaf is controlled by the dominance of peltate glandular trichome size over its number and is also affected by the capitate glandular trichome size/number with variations in leaf area albeit at lower proportions. Comprehension and comparison of results of GC-MS analysis of essential oils showed that most of the Ocimum (O. basilicum, O. tenuiflorum, and O. gratissimum) species produce phenylpropanoids (eugenol, methyl chavicol) as major volatiles except O. kilimandscharicum, which is discrete in being monoterpenoid-rich species. Among the phenylpropanoid-enriched Ocimum (O. basilicum, O. gratissimum, O. tenuiflorum purple, O. tenuiflorum green) as well, terpenoids were important constituents in imparting characteristic aroma. Further, comparative abundance of transcripts of key genes of phenylpropanoid (PAL, C4H, 4CL, CAD, COMT, and ES) and terpenoid (DXS and HMGR) biosynthetic pathways was evaluated vis-à-vis volatile oil constituents. Transcript abundance demonstrated that richness of their essential oils with specific constituent(s) of a chemical group/subgroup was manifested by the predominant upregulation of phenylpropanoid/terpenoid pathway genes. The study provides trichomes as well as biosynthetic pathway-based knowledge for genetic improvement in Ocimum species for essential oil yield and quality.


Essential oils Ocimum Phenylpropanoids Terpenoids Trichomes 



Ocimum basilicum


Ocimum gratissimum


Ocimum kilimandscharicum


Ocimum tenuiflorum (syn. Ocimum sanctum) green


Ocimum tenuiflorum (syn. Ocimum sanctum) purple


scanning electron microscopy


peltate glandular trichome density


peltate glandular trichome size


capitate glandular trichome density


capitate glandular trichome size


phenylalanine ammonia lyase




4-coumarate-CoA ligase


cinnamoyl alcohol dehydrogenase




eugenol synthase


3-hydroxy-3-methyl glutaryl coenzyme A reductase


1-deoxy-D-xylulose-5-phosphate synthase



SM acknowledges the Academy of Scientific and Innovative Research (AcSIR) for registration of Ph.D. program.

Author contributions

NSS conceived and devised the whole study plan. NSS, RSS, SM, and MC wrote the manuscript. SM, MC, RKY, and LKN conducted experiments. SM, PPS, US, DK, SB, RSS, MC, and LKN helped in resource and data generation. NSS supervised at each stage.

Funding information

The authors are thankful to HCP-007, BSC-203, and BSC-107 CSIR network project for providing financial assistance. MC is thankful to CSIR, New Delhi and UGC, New Delhi for research fellowship.

Compliance with ethical standards

Conflict of interest

The authors declare that there is no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Supplementary material

709_2018_1338_MOESM1_ESM.docx (36 kb)
Supplementary Fig. 1 Leaf area of the Ocimum species/cultivars. (OB), O. basilicum; (OG), O. gratissimum; (OK), O. kilimandscharicum; (OSG), O. tenuiflorum green; and (OSP), O. tenuiflorum purple. (DOCX 35 kb)
709_2018_1338_MOESM2_ESM.docx (19 kb)
Supplementary Table 1 List of primers used in real time expression analysis (DOCX 18 kb)


  1. Abdollahi MB, Eyvazpour E, Ghadimzadeh M (2017) The effect of drought stress on the expression of key genes involved in the biosynthesis of phenylpropanoids and essential oil components in basil (Ocimum basilicum L.). Phytochemistry 139:1–7. CrossRefGoogle Scholar
  2. Adedeji O, Ajuwon OY, BO O (2007) Foliar epidermal syudies, organographic distribution of trichomes in the family Solanaceae. Int J Bot 3:276–282CrossRefGoogle Scholar
  3. Ascensão L (1995) Glandular trichomes on vegetative and reproductive organs of Leonotis leonurus (Lamiaceæ). Ann Bot 75:619–626. CrossRefGoogle Scholar
  4. Ascensão L, Mota L, Castro MDM (1999) Glandular trichomes on the leaves and flowers of Plectranthus ornatus: morphology, distribution and histochemistry. Ann Bot 84:437–447. CrossRefGoogle Scholar
  5. Bansal S, Narnoliya LK, Mishra B, Chandra M, Yadav RK, Sangwan NS (2018) HMG-CoA reductase from Camphor Tulsi (Ocimum kilimandscharicum) regulated MVA dependent biosynthesis of diverse terpenoids in homologous and heterologous plant systems. Sci Rep 8:3547–3561. CrossRefGoogle Scholar
  6. Barton KE, Boege K (2017) Future directions in the ontogeny of plant defence: understanding the evolutionary causes and consequences. Ecol Lett 20:403–411. CrossRefGoogle Scholar
  7. Bayala B, Bassole IHN, Gnoula C, Nebie R, Yonli A, Morel L, Figueredo G, Nikiema JB, Lobaccaro JMA, Simpore J (2014) Chemical composition, antioxidant, anti-inflammatory and anti-proliferative activities of essential oils of plants from Burkina Faso. PLoS One 9:1–11. CrossRefGoogle Scholar
  8. Bhatt A, Naidoo Y, Nicholas A (2010) An investigation of the glandular and non-glandular foliar trichomes of Orthosiphon labiatus N.E.Br. [Lamiaceae]. N Z J Bot 48:153–161. CrossRefGoogle Scholar
  9. Bose SK, Yadav RK, Mishra S, Sangwan RS, Singh AK, Mishra B, Srivastava AK, Sangwan NS (2013) Effect of gibberellic acid and calliterpenone on plant growth attributes, trichomes, essential oil biosynthesis and pathway gene expression in differential manner in Mentha arvensis L. Plant Physiol Biochem 66:150–158. CrossRefGoogle Scholar
  10. Bouvier F, Rahier A, Camara B (2005) Biogenesis, molecular regulation and function of plant isoprenoids. Prog Lipid Res 44:357–429. CrossRefGoogle Scholar
  11. Chang X, Alderson PG, Wright CJ (2008) Solar irradiance level alters the growth of basil (Ocimum basilicum L.) and its content of volatile oils. Environ Exp Bot 63:216–223. CrossRefGoogle Scholar
  12. Charles DJ, Simon JE (1992) Essential oil constituents of Ocimum kilimandscharicum Guerke. J Essent Oil Res 4:125–128. CrossRefGoogle Scholar
  13. Chaurasiya ND, Sangwan NS, Sabir F, Mishra L, Sangwan RS (2012) Withanolide biosynthesis recruits both mevalonate and DOXP pathways of isoprenogenesis in ashwagandha Withania somnifera L. (Dunal). Plant Cell Rep 31:1889–1897. CrossRefGoogle Scholar
  14. Chiang LC, Ng LT, Cheng PW, Chiang W, Lin CC (2005) Antiviral activities of extracts and selected pure constituents of Ocimum basilicum. Clin Exp Pharmacol Physiol 32:811–816. CrossRefGoogle Scholar
  15. Croteau R, Kutchan TM, Lewis NG (2000) Secondary metabolites. Biochem Mol Biol Plants 7:1250–1318. Google Scholar
  16. Dai X, Wang G, Yang DS, Tang Y, Broun P, Marks MD, Sumner LW, Dixon RA, Zhao PX (2010) Trichome: a comparative omics database for plant trichomes. Plant Physiol 152:44–54. CrossRefGoogle Scholar
  17. Devi PU, Ganasoundari A, Vrinda B et al (2000) Radiation protection by the Ocimum flavonoids orientin and vicenin: mechanisms of action. Radiat Res 154:455–460.[0455:RPBTOF]2.0.CO;2Google Scholar
  18. Dhawan SS, Shukla P, Gupta P, Lal RK (2016) A cold-tolerant evergreen interspecific hybrid of Ocimum kilimandscharicum and Ocimum basilicum: analyzing trichomes and molecular variations. Protoplasma 253:845–855. CrossRefGoogle Scholar
  19. Eisenreich W, Bacher A, Arigoni D, Rohdich F (2004) Biosynthesis of isoprenoids via the non-mevalonate pathway. Cell Mol Life Sci 61:1401–1426. CrossRefGoogle Scholar
  20. Fernandes VF, de Almeida LB, Feijó EVR d S, Silva DC, de Oliveira RA, Mielke MS, Costa LCB (2013) Light intensity on growth, leaf micromorphology and essential oil production of Ocimum gratissimum. Rev Bras Farmacogn 23:419–424. CrossRefGoogle Scholar
  21. Gairola S, Naidoo Y, Bhatt A, Nicholas A (2009) An investigation of the foliar trichomes of Tetradenia riparia (Hochst.) Codd [ Lamiaceae]: an important medicinal plant of Southern Africa. Flora 204:325–330. CrossRefGoogle Scholar
  22. Gang DR (2001) An investigation of the storage and biosynthesis of phenylpropenes in sweet basil. Plant Physiol 125:539–555. CrossRefGoogle Scholar
  23. Gang DR, Simon J, Lewinsohn E, Pichersky E (2002) Peltate glandular trichomes of Ocimum basilicum L. (sweet basil) contain high levels of enzymes involved in the biosynthesis of phenylpropenes. J Herbs Spices Med Plants 9:189–195. CrossRefGoogle Scholar
  24. Gianfagna TJ, Carter CD, Sacalis JN (1992) Temperature and photoperiod influence trichome density and sesquiterpene content of Lycopersicon hirsutum f. hirsutum. Plant Physiol 100:1403–1405. CrossRefGoogle Scholar
  25. Huchelmann A, Boutry M, Hachez C (2017) Plant glandular trichomes: natural cell factories of high biotechnological interest. Plant Physiol 175:6–22. CrossRefGoogle Scholar
  26. Jadaun JS, Sangwan NS, Narnoliya LK, Singh N, Bansal S, Mishra B, Sangwan RS (2017) Over-expression of DXS gene enhances terpenoidal secondary metabolite accumulation in rose-scented geranium and Withania somnifera: active involvement of plastid isoprenogenic pathway in their biosynthesis. Physiol Plant 159(4):381–400CrossRefGoogle Scholar
  27. Jayanti I, Jalaluddin M, Avijeeta A, Ramanna PK, Rai PM, Nair RA (2018) In vitro antimicrobial activity of Ocimum sanctum (Tulsi) extract on Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. J Contemp Dent Pract 19:415–419CrossRefGoogle Scholar
  28. Jayasinghe C, Gotoh N, Aoki T, Wada S (2003) Phenolics composition and antioxidant activity of sweet basil (Ocimum basilicum L.). J Agric Food Chem 51:4442–4449. CrossRefGoogle Scholar
  29. Joshi RK, Hoti SL (2014) Chemical composition of the essential oil of Ocimum tenuiflorum L. (Krishna Tulsi) from North West Karnataka, India. Plant Sci Today 1:99–102. CrossRefGoogle Scholar
  30. Khare CP (2008) Indian medicinal plants—an illustrated dictionary. Springer-Verlag, HeidelbergGoogle Scholar
  31. Kolb D (2004) Light, conventional and environmental scanning electron microscopy of the trichomes of Cucurbita pepo subsp. pepo var. styriaca and histochemistry of glandular secretory products. Ann Bot 94:515–526. CrossRefGoogle Scholar
  32. Kothari SK, Bhattacharya AK, Ramesh S, Garg SN, Khanuja SPS (2005) Volatile constituents in oil from different plant parts of methyl eugenol-rich Ocimum tenuiflorum Lf (syn. O. sanctum L.) grown in south India. J Essent Oil Res 17:656–658. CrossRefGoogle Scholar
  33. Kumari R, Agrawal SB (2011) Comparative analysis of essential oil composition and oil containing glands in Ocimum sanctum L. (Holy basil) under ambient and supplemental level of UV-B through gas chromatography-mass spectrometry and scanning electron microscopy. Acta Physiol Plant 33:1093–1101. CrossRefGoogle Scholar
  34. Naidoo Y, Kasim N, Heneidak S, Nicholas A, Naidoo G (2013) Foliar secretory trichomes of Ocimum obovatum (Lamiaceae): micromorphological structure and histochemistry. Plant Syst Evol 299:873–885CrossRefGoogle Scholar
  35. Nakamura CV, Ishida K, Faccin LC, Filho BPD, Cortez DÁG, Rozental S, de Souza W, Ueda-Nakamura T (2004) In vitro activity of essential oil from Ocimum gratissimum L. against four candida species. Res Microbiol 155:579–586. CrossRefGoogle Scholar
  36. Narendhirakannan RT, Subramanian S, Kandaswamy M (2006) Biochemical evaluation of antidiabetogenic properties of some commonly used Indian plants on streptozotocin-induced diabetes in experimental rats. Clin Exp Pharmacol Physiol 33:1150–1157. CrossRefGoogle Scholar
  37. Navarro T, EL Oualidi J (2000) Trichome morphology in Teucrium L.(Labiatae). A taxonomic review. An del Jardín Botánico Madrid 57:277–297. Google Scholar
  38. Ogunkunle ATJ, Oladele FA (2000) Diagnostic value of trichomes in some Nigerian species of Ocimum Hyptis Jazq and Tinnea kotschy and Peys (Lamiaceae). J Appl Sci 3:1163–1180Google Scholar
  39. Okigbo R, Ogbonnaya U (2006) Antifungal effects of two tropical plant leaf extracts (Ocimum gratissimum and Aframomum melegueta) on postharvest yam (Dioscorea spp.) rot. African. J Biotechnol 5:727–731Google Scholar
  40. Oksanen E (2018) Trichomes form an important first line of defence against adverse environment—new evidence for ozone stress mitigation. Plant Cell Environ 41:1497–1499. CrossRefGoogle Scholar
  41. Padalia RC, Verma RS (2011) Comparative volatile oil composition of four Ocimum species from northern India. Nat Prod Res 25:569–575. CrossRefGoogle Scholar
  42. Paschapur MS, Patil MB, Kumar R, Patil SR (2009) Evaluation of aqueous extract of leaves of Ocimum kilimandscharicum on wound healing activity in albino wistar rats. Int J PharmTech Res 1:544–550Google Scholar
  43. Prakash P, Gupta N (2005) Therapeutic uses of Ocimum sanctum Linn (Tulsi) with a note on eugenol and its pharmacological actions: a short review. Indian J Physiol Pharmacol 49:125–131. Google Scholar
  44. Rao BRR, Kotharia SK, Rajput DK, Patel RP, Darokar MP (2011) Chemical and biological diversity in fourteen selections of four Ocimum species. Nat Prod Commun 6:1705–1710Google Scholar
  45. Rastogi S, Meena S, Bhattacharya A, Ghosh S, Shukla RK, Sangwan NS, Lal RK, Gupta MM, Lavania UC, Gupta V, Nagegowda DA, Shasany AK (2014) De novo sequencing and comparative analysis of holy and sweet basil transcriptomes. BMC Genomics 15:588–606. CrossRefGoogle Scholar
  46. Saharkhiz MJ, Kamyab AA, Kazerani NK et al (2015) Chemical compositions and antimicrobial activities of Ocimum sanctum L. essential oils at different harvest stages. Jundishapur J Microbiol 8:1–16Google Scholar
  47. Sangwan NS, Farooqi AHA, Shabih F, Sangwan RS (2001) Regulation of essential oil production in plants. Plant Growth Regul 34:3–21. CrossRefGoogle Scholar
  48. Sestili P, Ismail T, Calcabrini C, Guescini M, Catanzaro E, Turrini E, Layla A, Akhtar S, Fimognari C (2018) The potential effects of Ocimum basilicum on health: a review of pharmacological and toxicological studies. Expert Opin Drug Metab Toxicol 14:679–692. CrossRefGoogle Scholar
  49. Shanker S, AjayKumar PV, Sangwan N S, Kumar Sushil, Sangwan RS (1999) Essential oil gland number and ultrastructure during Mentha arvensis leaf ontogeny. Biol Plant 42:379–387Google Scholar
  50. Sharma S, Sangwan NS, Sangwan RS (2003) Developmental process of essential oil glandular trichome collapsing in menthol mint. Curr Sci 84:544–550Google Scholar
  51. Shetty S, Udupa S, Udupa L, Somayaji N (2006) Wound healing activity of Ocimum sanctum Linn with supportive role of antioxidant enzymes. Indian J Physiol Pharmacol 50:163–168Google Scholar
  52. Shirazi MT, Gholami H, Kavoosi G, Rowshan V, Tafsiry A (2014) Chemical composition, antioxidant, antimicrobial and cytotoxic activities of Tagetes minuta and Ocimum basilicum essential oils. Food Sci Nutr 2:146–155. CrossRefGoogle Scholar
  53. Silori CS, Dixit AM, Gupta L, Mistry N (2009) Observation on medicinal plant richness and associated conservation issues in district Kachchh, Gujarat. In: Trivedi PC (ed) Medicinal plants utilisation and conservation. pp 137–180Google Scholar
  54. Singh N, Luthra R, Sangwan R (1989) Effect of leaf position and age on the essential oil quantity and quality in lemongrass (Cymbopogon flexuosus). Planta Med 55:254–256. CrossRefGoogle Scholar
  55. Singletary KW (2018) Basil: a brief summary of potential health benefits. Nutr Today 53:92–97. CrossRefGoogle Scholar
  56. Telci I, Bayram E, Yılmaz G, Avcı B (2006) Variability in essential oil composition of Turkish basils (Ocimum basilicum L.). Biochem Syst Ecol 34:489–497. CrossRefGoogle Scholar
  57. Viña A, Murillo E (2003) Essential oil composition from twelve varieties of basil (Ocimum sp.) grown in Colombia. J Braz Chem Soc 14:744–749. CrossRefGoogle Scholar
  58. Wagner GJ (1991) Secreting glandular trichomes: more than just hairs. Plant Physiol 96:675–679. CrossRefGoogle Scholar
  59. Werker E (1993) Glandular hairs and essential oil in developing leaves of Ocimum basilicum L. (Lamiaceae). Ann Bot 71:43–50. CrossRefGoogle Scholar
  60. Yadav RK, Sangwan RS, Sabir F, Srivastava AK, Sangwan NS (2014) Effect of prolonged water stress on specialized secondary metabolites, peltate glandular trichomes, and pathway gene expression in Artemisia annua L. Plant Physiol Biochem 74:70–83. CrossRefGoogle Scholar
  61. Yadav RK, Sangwan RS, Srivastava AK, Sangwan NS (2017) Prolonged exposure to salt stress affects specialized metabolites-artemisinin and essential oil accumulation in Artemisia annua L.: metabolic acclimation in preferential favour of enhanced terpenoid accumulation accompanying vegetative to reproductive phase. Protoplasma 254:505–522. CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  • Shiwani Maurya
    • 1
    • 2
  • Muktesh Chandra
    • 1
  • Ritesh K. Yadav
    • 1
  • Lokesh K. Narnoliya
    • 1
  • Rajender S. Sangwan
    • 1
    • 2
    • 3
  • Shilpi Bansal
    • 1
    • 2
  • Pankajpreet Sandhu
    • 3
  • Umesh Singh
    • 3
  • Devender Kumar
    • 1
  • Neelam Singh Sangwan
    • 1
    • 2
    Email author
  1. 1.Department of Metabolic and Structural BiologyCSIR-Central Institute of Medicinal and Aromatic PlantsLucknowIndia
  2. 2.CSIR- Human Resource Development Centre CampusAcademy of Scientific and Innovative Research (AcSIR)GhaziabadIndia
  3. 3.Center of Innovative and Applied Bioprocessing (A National Institute under the Department of Biotechnology, Govt. of India)S.A.S. Nagar, MohaliIndia

Personalised recommendations