Author(s)

Flávio Couto Cordeiro^1*, Claudete Santa-Catarina², Vanildo Silveira³, Roberta Cristiane Ribeiro^4,5, Sonia Regina de Souza⁵

¹Plant Biochemistry Laboratory (LBP), Department of Chemistry, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica, Brazil.
²Cell Biology and Tissue Laboratory (LBCT), Center for Bioscience and Biotechnology (CBB), State University of Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, Brazil.
³Biotechnology Laboratory (LBT), Center for Bioscience and Biotechnology (CBB), State University of Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, Brazil.
⁴Plant Nutrition Laboratory (LNP), Department of Soils, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica, Brazil.
⁵Instituto Federal de Educacao, Ciência and Tecnologia of Mato Grosso (IFMT), Sorriso, Brazil.
⁵Plant Biochemistry Laboratory (LBP), Department of Chemistry, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica, Brazil.

The bioactivity of humic acids (HA) is mainly due to the presence of auxin analogs. In turn, nitric oxide (NO) production in plants affects root growth and may result from endogenous auxin production or the application of synthetic auxin analogs or HA. Nitric oxide signaling may be related to the bioactivity of the HA. Although the auxin, NO, and ROS-mediated activity of HA has been studied, no studies exist on their effects in Ocimum basilicum L., commonly known as basil. A study under controlled in vitro conditions was performed using hairy roots (hairy roots) of basil grown in medium with N-NO₃^- (0.5 or 5.0 mM) and subjected to treatments with HA (3 mMC·L^-1) or sodium nitroprusside (SNP; 100 μM), an NO donor, either without or with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO; 200 μM), an NO scavenger. The addition of HA and SNP resulted in significant increases in the root growth, associated with increased NO and reactive oxygen species (ROS) contents. The application of the NO scavenger cPTIO with the SNP and HA decreased the effects of both substances on the root growth and endogenous levels of the NO and ROS. The increased root growth promoted by the NO donor (SNP) and HA was also associated with increased proton pump and catalase activity for both N-NO₃^- levels tested. The results showed that the effects of HA are dependent on NO and ROS, which act as messengers, inducing root growth.

H+-ATPases, Auxins, Humic Acid, Ocimum basilicum L., Root Growth

Cordeiro, F. , Santa-Catarina, C. , Silveira, V. , Ribeiro, R. and de Souza, S. (2017) Humic Acid-Induced Hairy Root Growth in Basil Ismodulated by Nitric Oxide and Reactive Oxygen Species. American Journal of Plant Sciences, 8, 3140-3161. doi: 10.4236/ajps.2017.812212.