TITLE:
Humic Acid-Induced Hairy Root Growth in Basil Ismodulated by Nitric Oxide and Reactive Oxygen Species
AUTHORS:
Flávio Couto Cordeiro, Claudete Santa-Catarina, Vanildo Silveira, Roberta Cristiane Ribeiro, Sonia Regina de Souza
KEYWORDS:
H+-ATPases, Auxins, Humic Acid, Ocimum basilicum L., Root Growth
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.12,
November
27,
2017
ABSTRACT: 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.