Abstract
Arabidopsis CPR5 is involved in regulation of ethylene signaling via two different ways: interacting with the ETR1 N-terminal domains, and controlling nucleocytoplasmic transport of ethylene-related mRNAs. The ETR1 receptor plays a predominant role in ethylene signaling in Arabidopsis thaliana. Previous studies showed that both RTE1 and CPR5 can directly bind to the ETR1 receptor and regulate ethylene signaling. RTE1 was suggested to promote the ETR1 receptor signaling by influencing its conformation, but little is known about the regulatory mechanism of CPR5 in ethylene signaling. In this study, we presented the data showing that both RTE1 and CPR5 bound to the N-terminal domains of ETR1, and regulated ethylene signaling via the ethylene receptor. On the other hand, the research provided evidence indicating that CPR5 could act as a nucleoporin to regulate the ethylene-related mRNAs export out of the nucleus, while RTE1 or its homolog (RTH) had no effect on the nucleocytoplasmic transport of mRNAs. Nuclear qRT-PCR analysis and poly(A)-mRNA in situ hybridization showed that defect of CPR5 restricted nucleocytoplasmic transport of mRNAs. These results advance our understanding of the regulatory mechanism of CPR5 in ethylene signaling.
Highlights
Ethylene is the simplest gaseous plant hormone and widely distributed in plant tissues and cells
As both CPR5 and RTE1 can directly bind to the ETR1 receptor (Dong et al, 2010; Wang et al, 2017), we attempted to examine whether they bind to the same site on the receptor
The present study provided evidence indicating that CPR5 may act as a nucleoporin in regulating the nucleocytoplasmic transport of the mRNAs in ethylene signaling pathway, whereas RTE1 or its homolog (RTH) had no effect on the mRNAs nucleocytoplasmic transport (Figures 4, 5)
Summary
Ethylene is the simplest gaseous plant hormone and widely distributed in plant tissues and cells. Previous studies showed that ethylene, as an important plant hormone, played important roles in regulating plant growth and development, such as seed germination, fruit maturity, flower development, sex determination (Kamachi et al, 1997; Yamasaki et al, 2000), and leaf development, senescence and abscission (Bieleski and Reid, 1992; Kieber and Ecker, 1993; Guerrero et al, 1998). When ethylene or ethylene precursor ACC was added to the medium, the dark-grown Arabidopsis seedlings exhibited typical characteristics, termed the ethylene “triple response” with exaggerated apical hook, inhibited root and hypocotyl elongation, and swelled hypocotyl (Bleecker et al, 1988; Guzmán and Ecker, 1990). Using the ethylene “triple response” assay, a large number of Arabidopsis mutants with altered ethylene sensitivity were isolated. Based on genetic studies of the ethylene responsive mutants, a linear ethylene signal transduction pathway emerged (Bleecker et al, 1988; Guzmán and Ecker, 1990; Kieber et al, 1993; Roman and Ecker, 1995; Guo and Ecker, 2004)
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