Mitochondrial dynamics in plant male gametophyte visualized by fluorescent live imaging.
Visualization of organelles in living cells is a powerful method for studying their dynamic behavior. Here we attempted to visualize mitochondria in angiosperm male gametophyte (pollen grain from Arabidopsis thaliana) that are composed of one vegetative cell (VC) and two sperm cells (SCs). Combination of mitochondria-targeted fluorescent proteins with VC- or SC-specific expression allowed us to observe the precise number and dynamic behavior of mitochondria in the respective cell types. Furthermore, live imaging of SC mitochondria during double fertilization confirmed previous observations, demonstrated by electron microscopy in other species, that sperm mitochondria enter into the egg and central cells. We also attempted to visualize mutant mitochondria that were elongated due to a defect in mitochondrial division. This mutant phenotype was indeed detectable in VC mitochondria of a heterozygous F(1) plant, suggesting active mitochondrial division in male gametophyte. Finally, we performed mutant screening and isolated a putative mitochondrial protein transport mutant whose phenotype was detectable only in haploid cells. The transgenic materials presented in this work are useful not only for live imaging but also for studying mitochondrial functions by mutant analysis.
Research Institute for Bioresources, Okayama University, Kurashiki, Okayama, 710-0046 Japan.
Ryo
R
Matsushima
Yuki
Y
Hamamura
Tetsuya
T
Higashiyama
Shin-ichi
S
Arimura
Sodmergen
Nobuhiro
N
Tsutsumi
Wataru
W
Sakamoto
D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism; D003433:Crosses, Genetic; D005306:Fertilization; D005854:Germ Cells / Q000166:cytology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D050505:Mutant Proteins / Q000302:isolation & purification / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D030821:Plants, Genetically Modified; D011058:Pollen / Q000166:cytology*; D021381:Protein Transport
D029681:Arabidopsis Proteins; D050505:Mutant Proteins; C486924:dynamin-related protein DRP3A, Arabidopsis; D049452:Green Fluorescent Proteins