The AWPM-19 Family Protein OsPM1 Mediates Abscisic Acid Influx and Drought Response in Rice

Abstract

Abscisic acid (ABA) regulates plant stress responses and development. However, how the ABA signal is transmitted in response to stresses remains largely unclear, especially in monocots. In this study, we found that rice () OsPM1 (PLASMA MEMBRANE PROTEIN1), encoded by a gene of AWPM-19 like family, mediates ABA influx through the plasma membrane. is predominantly expressed in vascular tissues, guard cells, and mature embryos. Phenotypic analysis of overexpression, RNA interference (RNAi), and knockout (KO) lines showed that OsPM1 is involved in drought responses and seed germination regulation.H-(±)ABA transport activity and fluorescence resonance energy transfer assays both demonstrated that OsPM1 facilitates ABA uptake into cells. The physiological isomer of ABA, (+)-ABA, is the preferred substrate of OsPM1. Higher ABA accumulation and faster stomatal closure in response to ABA treatment were observed in the overexpression lines compared with the wild-type control. Many ABA-responsive genes were upregulated more in the -overexpression lines but less in the RNAi lines compared with wild-type plants. Further investigation revealed that expression is regulated by the AREB/ABF family transcription factor OsbZIP46. Our results thus revealed that OsPM1 is an ABA influx carrier that plays an important role in drought responses.

Abscisic acid dynamics, signaling, and functions in plants

“…ABAH can diffuse passively through the plasma membrane, and the diffusion of ABA largely declines with alkalization of the cytoplasm which increases during osmotic stresses (Wilkinson and Davies 1997; Karuppanapandian et al 2017). The active transport of ABA relies on: (i) ATP‐binding cassette (ABCG) transporters; (ii) NRT1/PTR (NPF); (iii) multidrug and toxic compound extrusion (MATE)‐type/DTX transporters (DTX50); and (iv) AWPM‐19 family proteins (OsPM1), which were originally identified in rice (Kuromori et al 2010, 2011; Kanno et al 2012; Zhang et al 2014; Kang et al 2015; Yao et al 2018).…”

Transcriptome and translatome profiling and translational network analysis during seed maturation reveals conserved transcriptional and distinct translational regulatory patterns

“…The PM19L1 homolog was originally identified in wheat ( Triticum aestivum ) as AWPM-19 (ABA-induced Wheat Plasma Membrane Polypeptide-19), which responses to ABA-induced freezing tolerance (Koike et al, 1997). Recently a rice homolog OsPM1 is identified as associated with ABA induced drought tolerance and seed germination speed (Yao et al, 2018). With SeedTransNet, we could further validate its down-stream target AT2G05580.…”

Form, development and function of grass stomata

“…Mutants and RNAi lines showed less ABA in GCs upon ABA application and lost more water, which indicates a defect in closing stomata properly (Matsuda et al , ). Similarly, OsPM1 (PM protein 1) is induced by ABA treatment, mediates ABA influx to the GCs in rice and is expressed in GCs but also in vascular tissues and mature embryos (Yao et al , ). Overexpression lines conferred a slightly higher drought resilience likely due to faster ABA accumulation in GCs and thus faster stomatal closure (Yao et al , ).…”

“…Similarly, OsPM1 (PM protein 1) is induced by ABA treatment, mediates ABA influx to the GCs in rice and is expressed in GCs but also in vascular tissues and mature embryos (Yao et al , ). Overexpression lines conferred a slightly higher drought resilience likely due to faster ABA accumulation in GCs and thus faster stomatal closure (Yao et al , ). Likely, homologues of the Arabidopsis ABA receptors AtPYR1/PYL/RCAR (Ma et al , ; Park et al , ) perceive ABA in GCs and trigger signalling and stomatal closure in grasses.…”