OsRACK1 is involved in abscisic acid- and H2O2-mediated signaling to regulate seed germination in rice (Oryza sativa, L.).

Dongping Zhang,Yun Chen,Bing Lv,Dahong Li,Li Chen,Jiansheng Liang,Xuejiaoyan Xuejiaoyan,Jingui Chen,Tai Wang

doi:10.1371/journal.pone.0097120

Dongping Zhang, Yun Chen + Show 7 more

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https://doi.org/10.1371/journal.pone.0097120

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Abstract

The receptor for activated C kinase 1 (RACK1) is one member of the most important WD repeat–containing family of proteins found in all eukaryotes and is involved in multiple signaling pathways. However, compared with the progress in the area of mammalian RACK1, our understanding of the functions and molecular mechanisms of RACK1 in the regulation of plant growth and development is still in its infancy. In the present study, we investigated the roles of rice RACK1A gene (OsRACK1A) in controlling seed germination and its molecular mechanisms by generating a series of transgenic rice lines, of which OsRACK1A was either over-expressed or under-expressed. Our results showed that OsRACK1A positively regulated seed germination and negatively regulated the responses of seed germination to both exogenous ABA and H2O2. Inhibition of ABA biosynthesis had no enhancing effect on germination, whereas inhibition of ABA catabolism significantly suppressed germination. ABA inhibition on seed germination was almost fully recovered by exogenous H2O2 treatment. Quantitative analyses showed that endogenous ABA levels were significantly higher and H2O2 levels significantly lower in OsRACK1A-down regulated transgenic lines as compared with those in wildtype or OsRACK1A-up regulated lines. Quantitative real-time PCR analyses showed that the transcript levels of OsRbohs and amylase genes, RAmy1A and RAmy3D, were significantly lower in OsRACK1A-down regulated transgenic lines. It is concluded that OsRACK1A positively regulates seed germination by controlling endogenous levels of ABA and H2O2 and their interaction.

Highlights

Seed germination is a complex processes that is under combinatorial control by endogenous and environmental cues
We observed that hypersensitivity of anti-sense transgenic lines (AsTLs) and RNA-interfered transgenic lines (RiTLs) to Abscisic acid (ABA) inhibition of germination was ABA dosage-dependent (Figure S3). These results indicated that the suppression of ABA catabolism rather than an enhancement of ABA biosynthesis may be the major factor for the delay of germination and OsRACK1A may exert its effect by controlling ABA metabolism
We and several other research teams have studied the roles of receptor for activated C kinase 1 (RACK1) in plant growth and development and in the responses to environmental cues and found that RACK1 is involved in regulating cell proliferation and elongation, inoculation and the responses to plant hormones and environmental factors [28],[35], [37], [44], [45]

Summary

Introduction

Seed germination is a complex processes that is under combinatorial control by endogenous and environmental cues. Bassel et al.[7], using publicly available gene expression data from Arabidopsis thaliana, generated a condition-dependent network model of global transcriptional interactions associated with seed dormancy or germination and identified 1,583 transcripts were associated with germination. He et al.[3] analyzed the protein profiling in the germinating rice seeds through 1-DE via LC MS/MS proteomic shotgun strategy and identified that a total of 673 proteins were involved in seed germination. Others included many regulatory proteins which control cellular redox homeostasis and gene expression of the germinating seeds

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