Melatonin‐rich transgenic rice plants exhibit resistance to herbicide‐induced oxidative stress

Abstract

To examine whether melatonin-rich plants can defend against oxidative stress, we subjected melatonin-rich transgenic (MRT) rice plants to the singlet-oxygen-generating herbicide butafenacil. Both MRT and transgenic control (TC; expressing the vector only) rice seeds germinated and grew equally well in continuous dark on half-strength Murashige and Skoog (MS) medium containing 0.1 μm butafenacil. However, after transferring the seedlings to light, the TCs rapidly necrotized, whereas the MRT seedlings showed resistant phenotypes. Seven-day-old MRT seedlings treated with 0.1 μm butafenacil were resistant to the herbicide and contained high chlorophyll levels and low malondialdehyde and hydrogen peroxide contents compared with the TCs. As they did before the herbicide treatment, the MRT plants also produced much more melatonin after the herbicide treatment than the TCs. In addition, the MRT plants exhibited higher superoxide dismutase and catalase activities before and after the herbicide treatment compared with the TCs. This is the first report showing that MRT plants exhibit resistance against a peroxidizing herbicide that acts by generating reactive oxygen species (ROS) that kill plants. This result indicates that melatonin scavenges ROS efficiently in vivo in the transgenic plants, leading to oxidative stress resistance.

Melatonin, an underestimated natural substance with great potential for agricultural application

“…Transgenic rice plants rich in MEL were more resistant to butafenacil, a herbicide which induces oxidative stress (Park et al 2013b). Due to antioxidant properties, MEL protected the roots of barley from the damaging effects of NaCl, ZnSO 4 and H 2 O 2 (Tan et al 2010).…”

The levels of melatonin and its metabolites in conditioned corn (Zea mays L.) and cucumber (Cucumis sativus L.) seeds during storage

“…It seems that this indoleamine plays a significant role in plant stress defense. It was observed that melatonin-rich plant species showed higher capacity for tolerance of unfavorable conditions (Park et al 2013;Bajwa et al 2014;Zhang et al 2015). Moreover, exogenously applied melatonin improved resistance to Marssonina apple blotch caused by Diplocarpon mali-dangerous pathogen that generates losses in the cultivation of apples (Yin et al 2013).…”

Cloning of Arabidopsis serotonin N‐acetyltransferase and its role with caffeic acid O‐methyltransferase in the biosynthesis of melatonin in vitro despite their different subcellular localizations

“…Its levels vary between species, ranging from a few picograms to micrograms per gram of tissue [11]. Melatonin is implicated in pleotropic functions in plants as a potent antioxidant [12], growth promoter [13,14], flowering and senescence inhibitor [15,16], and protector against various abiotic and biotic stresses such as salt, heavy metals, temperatures, drought, and pathogens [17][18][19][20][21][22]. These physiological functions of melatonin are closely associated with a diverse array of gene regulation in response to melatonin [23][24][25][26].…”