Thiourea mediated ROS-metabolites reprogramming restores root system architecture under arsenic stress in rice

Arsenic (As) is a ubiquitous carcinogenic metalloid that enters into human food chain, through rice consumption. To unravel the conundrum of oxidative vs. reductive stress, the differential root-system architecture (RSA) was studied under As (a ROS producer) and thiourea (TU; a ROS scavenger) alone treatments, which indicated 0.80-and 0.74-fold reduction in the number of lateral roots (NLR), respectively compared with those of control. In case of As+TU treatment, NLR was increased by 4.35-fold compared with those of As-stress, which coincided with partial restoration of redox-status and auxin transport towards the root-tip. The expression levels of 16 ROS related genes, including RBOHC, UPB-1 C, SHR1, PUCHI, were quantified which provided the molecular fingerprint, in accordance with endogenous ROS signature. LC-MS based untargeted and targeted metabolomics data revealed that As-induced oxidative stress was metabolically more challenging than TU alone-induced reductive stress. Cis/trans-ferruloyl putrescine and gamma-glutamyl leucine were identified as novel As-responsive metabolites whose levels were decreased and increased, respectively under As+TU than As-treated mots. In addition, the overall amino acid accumulation was increased in As+TU than As-treated roots, indicating the improved nutritional availability. Thus, the study revealed dynamic interplay between ROS-metabolites-RSA, to the broader context of TU-mediated amelioration of As-stress in rice.

Automated summary

This study investigated the toxic effects of arsenic in rice and the mitigating effects of thiourea. The results showed that arsenic and thiourea treatments had different impacts on root system architecture, with thiourea partially restoring redox status and auxin transport in the roots, reducing the toxicity of arsenic. Metabolomic data also revealed that arsenic-induced oxidative stress was more challenging metabolically, while thiourea increased amino acid accumulation and improved nutritional availability.