Abstract
ROP (Rho-like GTPases from plants) GTPases are polarly localized key regulators of polar growth in pollen tubes and other cells in plants. However, how ROP GTPases are regulated and how they control polar growth remains to be fully understood. To gain new insights into ROP-dependent mechanisms underlying polar cell growth, we characterized the interactome of ROP1 GTPase that controls Arabidopsis pollen tube (PT) tip growth, an extreme form of polar cell growth. We established an efficient method for culturing Arabidopsis pollen tubes in liquid medium, which was used for immunoprecipitation/mass spectrometry-based identification of ROP1-associated proteins. A total of 654 candidates were isolated from the ROP1 interactome in Arabidopsis pollen tubes, and GO (Gene Ontology) classification and pathway analysis revealed multiple uncharacterized ROP1-dependent processes including translation, cell wall modification, post transcriptional modification, and ion homeostasis, in addition to known ROP1-dependent pathways. The ROP1-interactome data was further supported by the co-expression of the candidate interactors in highly mature pollen with PT germination and growth defects being discovered in 25% (8/32) of the candidate mutant genes. Taken together, our work uncovers valuable information for the identification and functional elucidation of ROP-associated proteins in the regulation of polar growth, and provides a reliable reference to identify critical regulators of polar cell growth in the future.
Highlights
The establishment and maintenance of cell polarity plays a pivotal role in growth, development, and survival of various organisms [1]
Tip growth is an extreme form of polar growth, showing cell expansion restricted to the apical domain, and this growth model is utilized for functional specification of cells with long tube-like shapes, such as pollen tubes for sperm delivery into the ovary, plant root hair elongation for nutrient foraging in soil, fungal hyphal growth for host invasion, and the extension of neuronal axons for signal transmission in animals [2,3,4]
In order to dissect the molecular mechanism of polar tip growth, we initiated the screening of ROP1 associated proteins by affinity purification using beads covalently conjugated with GFP (Green Fluorescence Protein) antibody in cultured Arabidopsis pollen tube (PT)
Summary
The establishment and maintenance of cell polarity plays a pivotal role in growth, development, and survival of various organisms [1]. Tip-growing pollen tubes are regarded as an excellent model for deciphering the regulatory mechanisms underlying polar tip growth in plants [5,6,7]. The similarity of pollen tube growth patterns in vivo and in vitro indicated pollen tube tip growth is a self-organized regulatory system maintained by an autocrine signal [11], where the internal ROP1 signaling pathway plays a central role in orchestrating and maintaining the tip region and polar growth of PT through downstream effectors [5,7,12,13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
