Reactive Sulfur Species Interact with Other Signal Molecules in Root Nodule Symbiosis in Lotus japonicus

Abstract

Reactive sulfur species (RSS) function as strong antioxidants and are involved in various biological responses in animals and bacteria. Few studies; however, have examined RSS in plants. In the present study, we clarified that RSS are involved in root nodule symbiosis in the model legume Lotus japonicus. Polysulfides, a type of RSS, were detected in the roots by using a sulfane sulfur-specific fluorescent probe, SSP4. Supplying the sulfane sulfur donor Na2S3 to the roots increased the amounts of both polysulfides and hydrogen sulfide (H2S) in the roots and simultaneously decreased the amounts of nitric oxide (NO) and reactive oxygen species (ROS). RSS were also detected in infection threads in the root hairs and in infected cells of nodules. Supplying the sulfane sulfur donor significantly increased the numbers of infection threads and nodules. When nodules were immersed in the sulfane sulfur donor, their nitrogenase activity was significantly reduced, without significant changes in the amounts of NO, ROS, and H2S. These results suggest that polysulfides interact with signal molecules such as NO, ROS, and H2S in root nodule symbiosis in L. japonicus. SSP4 and Na2S3 are useful tools for study of RSS in plants.

Nitric Oxide Detoxification by <i>Mesorhizobium loti</i> Affects Root Nodule Symbiosis with <i>Lotus japonicus</i>

“…The endogenous production of NO in nodules at 4 and 6‍ ‍wpi was monitored by fluorescence microscopy, as described by Fukudome et al (2020) . The probes were dissolved in phosphate-buffered saline: 137‍ ‍mM NaCl, 2.7‍ ‍mM KCl, 8‍ ‍mM Na 2 HPO 4 , and 2‍ ‍mM NaH 2 PO 4 (pH 7.4).…”

Detection of sulfane sulfur species in biological systems

“…This probe has also been applied in a variety of systems including plants, bacterial, mammalian cells, etc. [ 26 , 27 ]. Kimura et al utilized a combination of SSP4, LC-FL and LC-MS/MS to identify the number of sulfur atoms in H 2 S n found in the brain and determine the producing enzyme [ 27 ].…”

Fluorescence Probes for Reactive Sulfur Species in Agricultural Chemistry

“…japonicus under distinct conditions (phosphate-buffer solution, probe 11 , or Na 2 S 3 + probe 11 ). This figure was reproduced with permission from ref [licensed under Creative Commons Attribution License (CC BY)]. Copyright 2020 Fukudome et al…”

“…Uchiumi et al used probe 11 derived from SSPs to perform fluorescence imaging in the legume Lotus japonicus. As expected, roots loaded with probe 11 exhibited significant fluorescence after being combined with cetyltrimethylammonium bromide.…”

“…When the probe reacted with the sulfane sulfurs, a fluorescein fluorophore was released, resulting in a significant increase in fluorescence (Figure 12A). Uchiumi et al 100 used probe 11 derived from SSPs to perform fluorescence imaging in the legume Lotus japonicus. As expected, roots loaded with probe 11 exhibited significant fluorescence after being combined with cetyltrimethylammonium bromide.…”