Ca2+ dynamics in a pollen grain and papilla cell during pollination of Arabidopsis.
Ca2+ dynamics in the growing pollen tube have been well documented in vitro using germination assays and Ca2+ imaging techniques. However, very few in vivo studies of Ca2+ in the pollen grain and papilla cell during pollination have been performed. We expressed yellow cameleon, a Ca2+ indicator based on green fluorescent protein, in the pollen grains and papilla cells of Arabidopsis (Arabidopsis thaliana) and monitored Ca2+ dynamics during pollination. In the pollen grain, [Ca2+]cyt increased at the potential germination site soon after hydration and remained augmented until germination. As in previous in vitro germination studies, [Ca2+]cyt oscillations were observed in the tip region of the growing pollen tube, but the oscillation frequency was faster and [Ca2+]cyt was higher than had been observed in vitro. In the pollinated papilla cell, remarkable increases in [Ca2+]cyt occurred three times in succession, just under the site of pollen-grain attachment. [Ca2+]cyt increased first soon after pollen hydration, with a second increase occurring after pollen protrusion. The third and most remarkable [Ca2+]cyt increase took place when the pollen tube penetrated into the papilla cell wall.
Iwano
Megumi
M
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan. m-iwano@bs.naist.jp
Shiba
Hiroshi
H
Miwa
Teruhiko
T
Che
Fang-Sik
FS
Takayama
Seiji
S
Nagai
Takeharu
T
Miyawaki
Atsushi
A
Isogai
Akira
A
D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D035264:Flowers / Q000166:cytology; D030821:Plants, Genetically Modified; D011058:Pollen / Q000254:growth & development / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology
D002118:Calcium