Distribution of hydrogen peroxide during adventitious roots initiation and development in mung bean hypocotyls cuttings

Abstract

Previous studies have shown that hydrogen peroxide (H 2 O 2 ) may mediate the auxin response during the formation of adventitious roots (AR). However, the mechanism and distribution of H 2 O 2 during AR formation remains unclear. In this study, we investigate the spatiotemporal changes and role of H 2 O 2 in AR initiation and development. Application of 5-100 mM H 2 O 2 to Mung bean (Phaseolus radiatus L.) hypocotyl cuttings induced AR formation in a dose-dependent manner. The effect was blocked by ascorbic acid (AA), an important reducing substrate for H 2 O 2 reduction. Depletion of endogenous H 2 O 2 by AA resulted in the significant reduction of AR emergence, suggesting a physiological role for H 2 O 2 in the regulation of AR formation. Determination of H 2 O 2 content showed that the level of H 2 O 2 increased gradually and reached the highest value 60 h after induction of AR. Further detection of endogenous H 2 O 2 by the specific fluorescent probe dichlorofluorescein diacetate (H 2 DCF-DA) and 3,3 0 -diaminobenzidine (DAB) staining in transverse sections of the basal region of cuttings revealed that obvious H 2 O 2 signals were observed in the pericycle cells between the vascular bundles 24 h after the primary roots were removed. With the development of root primordia, H 2 O 2 signals increased gradually and were mainly distributed in the root meristem. AA significant inhibited the H 2 O 2 -dependent fluorescence and the formation of AR, suggesting an essential role of H 2 O 2 generation during AR initiation and development. Furthermore, the involvement of Ca 2? during H 2 O 2 -mediated AR formation was evaluated. Ca 2? channel inhibitors LaCl 3 and ruthenium red (RR) and Ca 2? chelator ethylene glycol-bis(2-aminoethylether)-N,N,N 0 ,N 0 -tetraacetic acid (EGTA) prevent H 2 O 2 -induced AR formation, which indicate that the hypocotyl cuttings response to H 2 O 2 depends on the availability of both intracellular and extracellular Ca 2? pools, and Ca 2? is a downstream messenger in the signaling pathway triggered by H 2 O 2 to promote adventitious root formation.

Exogenous spermidine improves seed germination of sweet corn via involvement in phytohormone interactions, H2O2 and relevant gene expression

“…H 2 O 2 content (nmol · g · FW −1 ) in the embryos was colorimetrically measured as described by Huang et al [30] with minor modifications. 0.3 g of fresh seed embryos for each treatment was homogenized with 3 ml of cold acetone.…”

Extracellular superoxide production associated with secondary root growth following desiccation of Pisum sativum seedlings

“…Similarly, it was reported that H 2 O 2 can ameliorate desiccation stress in C. sativa embryonic axes (Roach et al, 2010). In addition, H 2 O 2 was required for adventitious root development in mung bean and cucumber and removing endogenous H 2 O 2 with ascorbate curtailed new root formation (Li et al, 2007;Huang et al, 2011). The left image shows O2 •− production in an untreated seedling prior to dehydration.…”

“…O 2 •− signaling has been associated with root hair growth (Foreman et al, 2003), cellular organization (Gapper and Dolan, 2006) and root gravitropism (Joo et al, 2001). In addition, growth of adventitious roots requires the presence of H 2 O 2 (Li et al, 2007;Huang et al, 2011). Catalyzed by superoxide dismutase, O 2 •− can be converted to H 2 O 2 , which can reversibly oxidize redox receptors, altering protein structure and function, thus perpetuating the signal (Stone and Yang, 2006).…”

Formación de raíces e inducción de haustorios de Castilleja tenuiflora Benth. con catequina y peróxido de hidrógeno. Root formation and haustoria induction of Castilleja tenuiflora Benth. with catechin and hydrogen peroxide

“…Esta diferencia puede deberse a diversas razones, como la síntesis de auxinas, su transporte o la aplicación exógena de éstas (De Klerk et al, 1999). Los tratamientos con H 2 O 2 resultaron en una menor cantidad de raíces, lo anterior a pesar de ser una molécula que puede participar en procesos como gravitropismo de la raíz o desarrollo de raíces laterales, y que funciona tanto como un mensajero en la formación de raíces adventicias mediada por auxinas o como un mediador de los eventos responsables del enraizamiento adventicio (Huang, 2011). Sin embargo, el H 2 O 2 es también una molécula que contribuye al estrés oxidativo, fenómeno común en plantas, y es posible que en este caso los brotes de C. tenuiflora hayan priorizado el activar su sistema de protección antioxidante para reducir los niveles de H 2 O 2 y esto no permitió su participación en la rizogénesis (Cheniany et al, 2010).…”