Arabidopsis PRK6 interacts specifically with AtRopGEF8/12 and induces depolarized growth of pollen tubes when overexpressed

• Published in: Science China. Life sciences 2018, Vol.61 (1), p.100-112
• Main Authors: Yu, Yuexuan, Song, Jiali, Tian, Xiaohui, Zhang, Haiwen, Li, Legong, Zhu, Huifen
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis; 试管; 花粉; 生长; 交往; 相互作用; 染色体编码; 屏幕显示; Binding Sites; Biomedical and Life Sciences; Gene Expression Regulation, Plant; Genomes; Guanine; Guanine nucleotide exchange factor; Guanine Nucleotide Exchange Factors - chemistry; Guanine Nucleotide Exchange Factors - metabolism; Kinases; Life Sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mesophyll; Models, Biological; Nicotiana - genetics; Pollen; Pollen Tube - genetics; Pollen Tube - growth & development; Pollen tubes; Protein Binding; Protein Serine-Threonine Kinases - chemistry; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; Protoplasts; Research Paper; Tobacco
• ISSN: 1674-7305; 1869-1889
• DOI: 10.1007/s11427-016-9107-3

The pollen receptor kinases （PRK） are critical regulators of pollen tube growth. The Arabidopsis genome encodes eight PRK genes, of which six are highly expressed in pollen tubes. The potential functions of AtPRK1 through AtPRK5, but not of AtPRK6,in pollen growth were analyzed in tobacco. Herein, AtPRK6 was cloned, and its function was identified. AtPRK6 was expressed specifically in pollen tubes. A yeast two-hybrid screen of AtPRK6 against 14 Arabidopsis Rop guanine nucleotide exchange factors （RopGEFs） showed that AtPRK6 interacted with AtRopGEF8 and AtRopGEF12. These interactions were confirmed in Arabidopsis mesophyll protoplasts. The interactions between AtPRK6 and AtRopGEF8/12 were mediated by the C-termini of AtRopGEF8/12 and by the juxtamembrane and kinase domain of AtPRK6, but were not dependent on the kinase activity. In addition, transient overexpression of AtPRK6：：GFP in Arabidopsis protoplasts revealed that AtPRK6 was localized to the plasma membrane. Tobacco pollen tubes overexpressing AtPRK6 exhibited shorter tubes with enlarged tips. This depolarized tube growth required the kinase domain of AtPRK6 and was not dependent on kinase activity. Taken together, the results show that AtPRK6,through its juxtamembrane and kinase domains （KD）, interacts with AtRopGEF8/12 and plays crucial roles in polarized growth of pollen tubes.