ABA-INDUCED expression 1 is involved in ABA-inhibited primary root elongation via modulating ROS homeostasis in Arabidopsis.

To endure environmental stresses, plants have evolved complex regulatory mechanisms involving phytohormones, including abscisic acid (ABA). The function of the plant-specific AT-rich sequence zinc-binding protein (PLATZ) family has not yet been extensively characterized in Arabidopsis (Arabidopsis thaliana). In this report, we evaluated the function of a putative member of the PLATZ family in Arabidopsis, ABA-INDUCED expression 1 (AIN1). We determined that AIN1 expression was induced by ABA and abiotic stresses. AIN1 overexpression (OE) enhanced ABA sensitivity and inhibited primary root elongation, but reduced expression of AIN1 in RNA interference (RNAi) plants produced roots less sensitive to ABA. When treated with ABA, we observed a reduction of meristem size and over-accumulation of reactive oxygen species (ROS) at the root tips of OE lines, demonstrating the importance of AIN1 in plant responses to ABA. A set of ROS scavenger genes showed reduced expression in the OE lines but improved in the RNAi plants relative to Col-0. In addition, we report that exogenous application of reduced glutathione (GSH) rescued the root growth defects seen in AIN1 overexpression lines treated with ABA. In summary, our results suggest that Arabidopsis AIN1 is involved in ABA-mediated inhibition of root elongation by modulating ROS homeostasis.

OsMADS18, a membrane-bound MADS-box transcription factor, modulates plant architecture and the abscisic acid response in rice.

The APETALA1 (AP1)/FRUITFULL (FUL)-like transcription factor OsMADS18 plays diverse functions in rice development, but the underlying molecular mechanisms are far from fully understood. Here, we report that down-regulation of OsMADS18 expression in RNAi lines caused a delay in seed germination and young seedling growth, whereas the overexpression of OsMADS18 produced plants with fewer tillers. In targeted OsMADS18 genome-edited mutants (osmads18-cas9), an increased number of tillers, altered panicle size, and reduced seed setting were observed. The EYFP-OsMADS18 (full-length) protein was localized to the nucleus and plasma membrane but the EYFP-OsMADS18-N (N-terminus) protein mainly localized to the nucleus. The expression of OsMADS18 could be stimulated by abscisic acid (ABA), and ABA stimulation triggered the cleavage of HA-OsMADS18 and the translocation of OsMADS18 from the plasma membrane to the nucleus. The inhibitory effect of ABA on seedling growth was less effective in the OsMADS18-overexpressing plants. The expression of a set of ABA-responsive genes was significantly reduced in the overexpressing plants. The phenotypes of transgenic plants expressing EYFP-OsMADS18-N resembled those observed in the osmads18-cas9 mutants. Analysis of the interaction of OsMADS18 with OsMADS14, OsMADS15, and OsMADS57 strongly suggests an essential role for OsMADS18 in rice development.