Implications of the fate of hydrogen sulfide derived from assimilation of thiocyanate in rice plants.

Thiocyanate (SCN) is a sulfur-containing pollutant, which is frequently detected in irrigation water and has negative effects on plant growth and crop yields. Uptake and assimilation of exogenous SCN in rice plants was evident, in which two metabolic pathways, carbonyl sulfide (COS) and cyanate (CNO), are activated. Hydrogen sulfide (HS) is an important concomitant derived from detoxification of exogenous SCN in rice plants, which may cause coupling action on the endogenous source of HS from sulfur metabolism. Since HS has dual regulatory effects, the fate of HS derived from assimilation of SCN in plants is critical for clarifying the inclusiveness of HS in various physiological activities. In fact, application of exogenous HS not only positively changed the root phenotype traits of SCN-treated seedlings, but also effectively mitigated the toxic effects of SCN in rice seedlings by stimulating the process of the PSII repair cycle. In this study, it is tempting to analyze and clarify the flux of the concomitant production of HS from assimilation of exogenous SCN into the innate pool, which may function in signaling regulation and other physiological processes in rice plants. This study would update our understanding of the fate of HS derived from assimilation of SCN in plants and provide new insights into the affirmative actions of HS in direct proximity to SCN exposure.