Morphological and anatomical changes in soybean roots subjected to indole-3-acetic acid and tryptophol: indole compounds present in plant auxin metabolism

  • Willian Rodrigues MacedoEmail author
  • Ana Lourença Vaz do Nascimento
  • Danúbia Aparecida Costa Nobre
  • Jaqueline Dias Pereira
  • Mirlem Gonçalves Rocha
Original Article


The auxin metabolism is practically elucidated, and the compounds that are part of the biosynthesis are well characterized, but the indole-3-ethanol or tryptophol, a molecule that has a regulatory position in the indole-3-acetic acid biosynthesis, still represents a gap in the understanding of this pathway. We examined the hypothesis that tryptophol present the function of plant growth regulation on soybean root development. We evaluated two doses of auxin and two doses of tryptophol (100 e 200 mg L− 1), respectively, beside a control treatment (water), via leaf application, in soybean plants under V1–V2 phonological stages. After 18 days of application, the roots were collected for their volume and area measurement, thereafter small segments (0.5 cm of length), were collected at 1 cm below the root-collar, for anatomical analysis. We observed that the control showed greater area and root volume, but using 200 mg L− 1 auxin and 100 mg L− 1 tryptophol led to a radial increase of roots with significant increases in width radius vascular and cortical parenchyma. These results suggest that the application of both compounds had a potential of modify the vascular and ground tissues in soybean roots, which may be beneficial for the development of plants.


Glycine max L. Indole compounds Vascular tissue Roots 



We are also grateful to National Council for Scientific and Technological Development (CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico), National Institute of Science and Technology - INCT BioNat, grant # 465637/2014-0, Brazil for support to the first author, and Ms. Eliane Vieira de Souza for assisting in image processing.

Author contribution

Willian Rodrigues Macedo: Design and conducted the experiment, collected and analyzed the data, and wrote the manuscript; Ana Lourença Vaz do Nascimento: conducted the experiment and collected the data; Danúbia Aparecida Costa Nobre: analyzed the data and wrote the manuscript; Jaqueline Dias Pereira: helped in the anatomical analysis and wrote the manuscript; Mirlem Gonçalves Rocha: carry out the anatomical analysis.

Supplementary material

11738_2018_2719_MOESM1_ESM.doc (54 kb)
Supplementary material 1 (DOC 53 KB)


  1. Ahmad A, Hayat S, Fariduddin Q, Ahmad I (2001) Photosynthetic efficiency of plants of Brassica juncea, treated with chlorosubstituted auxins. Photosynthetica 39:565–568CrossRefGoogle Scholar
  2. Alameda D, Villar R (2012) Linking root traits to plant physiology and growth in Fraxinus angustifolia Vahl. seedlings under soil compaction conditions. Environ Exp Bot 79:49–57. CrossRefGoogle Scholar
  3. Aloni R (2013) Role of hormones in controlling vascular differentiation and the mechanism of lateral root initiation. Planta 238:819–830. CrossRefPubMedGoogle Scholar
  4. Aloni R (2015) Ecophysiological implications of vascular differentiation and plant evolution. Trees Struct Funct 29:1–16. CrossRefGoogle Scholar
  5. Aloni R, Zimmermann MH (1983) The control of vessel size and density along the plant axis: a new hypothesis. Differentiation 24:203–208. CrossRefGoogle Scholar
  6. Cato SC, Macedo WR, Peres LEP, Castro PRC (2013) Sinergism among auxins, gibberellins and cytokinins in tomato cv. Micro-Tom. Hortic Bras. CrossRefGoogle Scholar
  7. Eliasson L, Bertell G, Bolander E (1989) Inhibitory action of auxin on root elongation not mediated by ethylene. Plant Physiol 91:310–314. CrossRefPubMedPubMedCentralGoogle Scholar
  8. Guzmán-López O, Trigos Á, Fernández FJ et al (2007) Tyrosol and tryptophol produced by Ceratocystis adiposa. World J Microbiol Biotechnol 23:1473–1477. CrossRefGoogle Scholar
  9. Johansen DA (1940) Plant Microtechnique. McGraw Hill Book, New YorkGoogle Scholar
  10. Kraus JE, Arduin M (1997) Manual básico de métodos em morfologia vegetal. Editora da UFRJ, SeropódicaGoogle Scholar
  11. Lacan G, Magnus V, Simaga S et al (1985) Metabolism of tryptophol in higher and lower plants. Plant Physiol 78:447–454CrossRefPubMedPubMedCentralGoogle Scholar
  12. Lebuhn M, Heulin T, Hartmann A (1997) Production of auxin and other inolic and phenolic compounds by Paenibacillus polymyxa strains isolated from different proximity to plant roots. FEMS Microbiol Ecol 22:325–334. CrossRefGoogle Scholar
  13. Ljung K (2013) Auxin metabolism and homeostasis during plant development. Development 140:943–950. CrossRefPubMedGoogle Scholar
  14. Ljung K, Östin A, Lioussanne L, Sandberg G (2001) Developmental regulation of indole-3-acetic acid turnover in scots pine seedlings. Plant Physiol 125:464–475. CrossRefPubMedPubMedCentralGoogle Scholar
  15. Nascimento ALV, Macedo WR, Silva GH et al (2016) Physiological and agronomical responses of common bean subjected to tryptophol. Ann Appl Biol 168:195–202. CrossRefGoogle Scholar
  16. Olson ME, Rosell JA (2013) Vessel diameter-stem diameter scaling across woody angiosperms and the ecological causes of xylem vessel diameter variation. New Phytol 197:1204–1213. CrossRefPubMedGoogle Scholar
  17. Percival FW, Purves WK, Vickery LE (1973) Indole-3-ethanol oxidase. Plant Physiol 51:739–743CrossRefPubMedPubMedCentralGoogle Scholar
  18. Perrot-Rechenmann C (2010) Cellular responses to auxin: division versus expansion. Cold Spring Harb Perspect Biol 2:1–15. CrossRefGoogle Scholar
  19. Persello-Cartieaux F, Nussaume L, Robaglia C (2003) Tales from the underground: molecular plant–rhizobacteria interactions. Plant Cell Environ 26:189–199. CrossRefGoogle Scholar
  20. Piotrowska-Niczyporuk A, Bajguz A (2014) The effect of natural and synthetic auxins on the growth, metabolite content and antioxidant response of green alga Chlorella vulgaris (Trebouxiophyceae). Plant Growth Regul 73:57–66. CrossRefGoogle Scholar
  21. Rajagopal R (1967) Metabolism of Indole-3-acetaldehyde. I. Distribution of indoleacetic acid and tryptopbol forming activities in plants. Physiol Plant 20:982–990CrossRefGoogle Scholar
  22. Ribeiro AC, Guimarães PTG, Alvarez VH (1999) Amostragem do Solo. Comissão de Fertilidade do Solo do Estado de Minas Gerais, ViçosaGoogle Scholar
  23. SAS Institute (2004) SAS/STAT 9.1 User’s Guide. SAS Institute Inc., CaryGoogle Scholar
  24. Shi H, Chen L, Ye T et al (2014) Modulation of auxin content in Arabidopsis confers improved drought stress resistance. Plant Physiol Biochem 82:209–217. CrossRefPubMedGoogle Scholar
  25. Takahashi H (2013) Auxin biology in roots. Plant Root 7:49–64. CrossRefGoogle Scholar
  26. Zazímalová E, Murphy AS, Yang H et al (2010) Auxin transporters—why so many? Cold Spring Harb Perspect Biol 2:a001552. CrossRefPubMedPubMedCentralGoogle Scholar

Copyright information

© Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków 2018

Authors and Affiliations

  1. 1.Institute of Agricultural SciencesUniversidade Federal de ViçosaRio ParanaíbaBrazil
  2. 2.Institute of Biological SciencesUniversidade Federal de ViçosaRio ParanaíbaBrazil

Personalised recommendations