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