Rice protein phosphatase 1 regulatory subunits OsINH2 and OsINH3 participate actively in growth and adaptive responses under abscisic acid

Abstract

Rice (Oryza sativa L.), a worldwide staple food crop, is affected by various environmental stressors that ultimately reduce yield. However, diversified physiological and molecular responses enable it to cope with adverse factors. It includes the integration of numerous signaling in which protein phosphatase 1 (PP1) plays a pivotal role. Research on PP1 has been mostly limited to the PP1 catalytic subunit in numerous cellular progressions. Therefore, we focused on the role of PP1 regulatory subunits (PP1r), OsINH2 and OsINH3, homologs of AtINH2 and AtINH3 in Arabidopsis, in rice growth and stress adaptations. Our observations revealed that these are ubiquitously expressed regulatory subunits that interacted and colocalized with their counter partners, type 1 protein phosphatase (OsTOPPs) but could not change their subcellular localization. The mutation in OsINH2 and OsINH3 reduced pollen viability, thereby affected rice fertility. They were involved in abscisic acid (ABA)-mediated inhibition of seed germination, perhaps by interacting with osmotic stress/ABA-activated protein kinases (OsSAPKs). Meanwhile, they positively participated in osmotic adjustment by proline biosynthesis, detoxifying reactive oxygen species (ROS) through peroxidases (POD), reducing malondialdehyde formation (MDA), and regulating stress-responsive genes. Moreover, their co-interaction proposed they might mediate cellular processes together or by co-regulation; however, the special behavior of two different PP1r is needed to explore. In a nutshell, this research enlightened the involvement of OsINH2 and OsINH3 in the reproductive growth of rice and adaptive strategies under stress. Hence, their genetic interaction with ABA components and deep mechanisms underlying osmotic regulation and ROS adjustment would explain their role in complex signaling. This research offers the basis for introducing stress-resistant crops.

Cytological Observation and RNA-Seq Analyses Reveal miR9564 and Its Target Associated with Pollen Sterility in Autotetraploid Rice

“…The STTM (Short Tandem Target Mimic) lines of miR528 in neo-tetraploid rice exhibited a significant reduction in seed setting and pollen fertility [ 34 ]. Here, we identified the OsINH2 gene as a novel candidate target of miR528 , which functions in regulating pollen viability and grain numbers [ 35 ]. In both H1/LF and HF/LF, miR528 was up-regulated during pollen development, while OsINH2 showed down-regulation.…”

The rice SnRK family: biological roles and cell signaling modules

“…These proteins also interact with various signaling components involved in plant responses to abiotic stress and ABA (Figure 3). As mentioned above, OsSAPK1-3 were identified as binding partners of OsbZIP46, OsbZIP62, OsPP2C09, OsINH2, and OsINH3, respectively (Tang et al, 2012;Miao et al, 2020;Jadoon et al, 2022), but the detailed mechanisms are unknown. OsSAPK1, OsSAPK2, and OsSAPK6 were also identified as interacting partners of OsbZIP62, which positively regulates plant tolerance to drought and oxidative stress (Yang et al, 2019).…”

“…OsSAPK-mediated TE phosphorylation impairs APC/C TE activity by degrading the ABA receptor OsPYL/RCARs including RCAR10, whereas GA induces OsSAPK degradation by APC/C TE (Lin et al, 2015). Rice Inhibitor 2 (OsINH2) and OsINH3, the regulatory subunits of the Protein phosphatase 1 complex, physically interact with the Type 1 protein phosphatases (OsTOPPs; OsTOPP1-5) and with OsSAPKs (i.e., OsSAPK1-3, OsSAPK8, and OsSAPK9) and negatively regulate ABA-mediated growth, development, and oxidative stress responses (Jadoon et al, 2022). TOPP1 and INH2/AtI-2 synergically reduce ABA signaling in Arabidopsis by inactivating OsSnRK2s, including OsSnRK2.6 (Hou et al, 2016).…”

The ZmbHLH47-ZmSnRK2.9 Module Promotes Drought Tolerance in Maize

“…In addition, as malondialdehyde (MDA) content and electrolyte leakage serve as indicative markers of drought tolerance [50,51], it was attempted to calculate these parameters for WT, ZmbHLH47-OE, and zmbhlh47-crispr plants. Prior to drought stress, MDA content and electrolyte leakage exhibited similar levels among WT, OE, and Crispr lines (Figure 1H,I).…”