Plant roots are constantly exposed to a variety of abiotic stresses, and high salinity is one of the major limiting conditions that impose constraints on plant growth. In this study, we describe that OsMADS25 is required for the root growth as well as salinity tolerance, via maintaining ROS homeostasis in rice (Oryza sativa). Overexpression of OsMADS25 remarkably enhanced the primary root (PR) length and lateral root (LR) density, whereas RNAi silence of this gene reduced PR elongation significantly, with altered ROS accumulation in the root tip. Transcriptional activation assays indicated that OsMADS25 activates OsGST4 (glutathione S–transferase) expression directly by binding to its promoter. Meanwhile, osgst4 mutant exhibited repressed growth and high sensitivity to salinity and oxidative stress, and recombinant OsGST4 protein was found to have ROS–scavenging activity in vitro. Expectedly, overexpression of OsMADS25 significantly enhanced the tolerance to salinity and oxidative stress in rice plants, with the elevated activity of antioxidant enzymes, increased accumulation of osmoprotective solute proline and reduced frequency of open stoma. Furthermore, OsMADS25 specifically activated the transcription of OsP5CR, a key component of proline biosynthesis, by binding to its promoter. Interestingly, overexpression of OsMADS25 raised the root sensitivity to exogenous ABA, and the expression of ABA–dependent stress–responsive genes was elevated greatly in overexpression plants under salinity stress. In addition, OsMADS25 seemed to promote auxin signaling by activating OsYUC4 transcription. Taken together, our findings reveal that OsMADS25 might be an important transcriptional regulator that regulates the root growth and confers salinity tolerance in rice via the ABA–mediated regulatory pathway and ROS scavenging.

GABA has beneficial effects on salinity stress tolerance in Arabidopsis linked to increased activity of H+-ATPase, reduced ROS-induced K+ efflux from root epidermis, and increased SOS1 and NHX1 transcript levels in plant roots.

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The aims of the study were to investigate whether hydrogen gas (H2) was involved in regulation of anthocyanin biosynthesis in two contrasting radish (Raphanus sativus L.) varieties (low [LA] and high [HA] level of anthocyanin) under UV irradiation. The results showed that hydrogen-rich water (HRW) significantly blocked the UV-A-induced increase of H2O2 and O2(•-) accumulation, and enhanced the UV-A-induced increase of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in LA and HA. Furthermore, UV-A-induced increase of anthocyanin and total phenols was further enhanced only in HA sprouts cotreated with HRW. LC-MS/MS analysis showed that five anthocyanidins existed in HA sprouts, but only two in LA sprouts. Meanwhile, the cyanidin was the most abundant anthocyanidin in HA, and the cyanidin was 2-fold higher cotreated with HRW than UV-A. Molecular analyses showed that the anthocyanin biosynthesis-related genes were upregulated significantly in both HA (in particular) and LA sprouts treated with HRW plus UV-A. These data imply that HRW reestablishes reactive oxygen species homeostasis in both LA and HA, but exerts different effects on anthocyanin accumulation between them under UV-A.