Dynamic morphologies of pollen plastids visualised by vegetative-specific FtsZ1–GFP in Arabidopsis thaliana
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The behaviour and multiplication of pollen plastids have remained elusive despite their crucial involvement in cytoplasmic inheritance. Here, we present live images of plastids in pollen grains and growing tubes from transgenic Arabidopsis thaliana lines expressing stroma-localised FtsZ1–green-fluorescent protein fusion in a vegetative cell-specific manner. Vegetative cells in mature pollen contained a morphologically heterogeneous population of round to ellipsoidal plastids, whilst those in late-developing (maturing) pollen included plastids that could have one or two constriction sites. Furthermore, plastids in pollen tubes exhibited remarkable tubulation, stromule (stroma-filled tubule) extension, and back-and-forth movement along the direction of tube growth. Plastid division, which involves the FtsZ1 ring, was rarely observed in mature pollen grains.
KeywordsArabidopsis thaliana FtsZ ring Leucoplast Plastid division Stromule
The authors are grateful to Prof. Danny J. Schnell (University of Massachusetts at Amherst, USA) for the gift of antiserum against Arabidopsis Tic110, Dr. Yasuo Niwa (University of Shizuoka, Japan) for the original GFP vector, Arabidopsis Biological Resource Center (Ohio State University, USA) for providing the arc11 seeds and Prof. Rachel M. Leech and Ms. Joanne L. Marrison (University of York, UK) for donating them. We also thank Dr. Yukihisa Shimada (RIKEN Plant Science Center, Japan), Dr. Takeshi Nakano, Ms. Sumie Ohbu (RIKEN), Mr. Tadasuke Chiba (KS Olympus, Japan) and the facility of RIKEN Radioactive Isotope Beam Factory for supporting this study. This work was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 17780077 to M.T.F., No. 20657015 to R.D.I.) and the Agricultural Chemical Research Foundation (to M.T.F. and R.D.I.).
Conflict of Interest
The authors declare that they have no conflict of interest.
Time-lapse observation of FtsZ1–GFP in a germinating pollen grain of the wild-type. Fluorescence images were taken for 120 s at 4-s intervals. Germination has occurred at the left part of grain; 120 s corresponds to 3.0 s in this movie. The pollen sample is the same as that in Fig. 4d. (MPG 380 kb)
Time-lapse observation of FtsZ1–GFP in germinated wild-type pollen. Fluorescence images were taken for 116 s at 4-s intervals. 116 s correspond to 2.9 s in this movie. The pollen sample is the same as that in Fig. 4f. (MPG 288 kb)
Z-series images of FtsZ1–GFP in a mature pollen grain of arc11. Fluorescence images taken for 52 s at 4-s intervals are shown in this movie. The pollen sample is the same as that in Fig. 5b. (MPG 232 kb)
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