Ni(2+) effects on Nicotiana tabacum L. pollen germination and pollen tube growth.
Biometals
; 25(6): 1221-33, 2012 Dec.
Article
in En
| MEDLINE
| ID: mdl-22983762
ABSTRACT
To investigate the mechanisms of Ni(2+) effects on initiation and maintenance of polar cell growth, we used a well-studied model system-germination of angiosperm pollen grains. In liquid medium tobacco pollen grain forms a long tube, where the growth is restricted to the very tip. Ni(2+) did not prevent the formation of pollen tube initials, but inhibited their subsequent growth with IC(50) = 550 µM. 1 mM Ni(2+) completely blocked the polar growth, but all pollen grains remained viable, their respiration was slightly affected and ROS production did not increase. Addition of Ni(2+) after the onset of germination had a bidirectional effect on the tubes development there was a considerable amount of extra-long tubes, which appeared to be rapidly growing, but the growth of many tubes was impaired. Studying the localization of possible targets of Ni(2+) influence, we found that they may occur both in the wall and in the cytoplasm, as confirmed by specific staining. Ni(2+) disturbed the segregation of transport vesicles in the tips of these tubes and significantly reduced the relative content of calcium in the aperture area of pollen grains, as measured by X-ray microanalysis. These factors are considered being critical for normal polar cell growth. Ni(2+) also causes the deposition of callose in the tips of the tube initials and the pollen tubes that had stopped their growth. We can assume that Ni(2+)-induced disruption of calcium homeostasis can lead to vesicle traffic impairment and abnormal callose deposition and, consequently, block the polar growth.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pollen
/
Nicotiana
/
Germination
/
Pollen Tube
/
Nickel
Type of study:
Prognostic_studies
Language:
En
Journal:
Biometals
Journal subject:
BIOQUIMICA
Year:
2012
Document type:
Article
Affiliation country:
Rusia