Species-dependent chromium accumulation, lipid peroxidation, and glutathione levels in germinating kiwifruit pollen under Cr(III) and Cr(VI) stress.
The accumulation of chromium by germinating kiwifruit pollen appears to be significantly affected by Cr species, Cr concentration and calcium availability. Cr(III) accumulation always occurred in a linear manner while Cr(VI) uptake followed a logarithmic model. In the absence of exogenous calcium, Cr(III) accumulation was much higher than that of Cr(VI). It was observed that, as the Cr(III) concentration increased, there was a significant decrease in the endogenous calcium content of pollen, ultimately leading to complete calcium depletion after 90 min of incubation at 150 microM Cr(III). This loss of calcium could be responsible for the strong inhibition of tube emergence and growth following exposure of pollen to Cr(III). Indeed, when exogenous calcium was added to the kiwifruit pollen culture medium, significant growth recovery and reduced Cr(III) uptake occurred; the opposite was true in Cr(VI)-treatments. A significant rise in lipid peroxide production occurs in the presence of both Cr species; the effect was more pronounced following Cr(VI) exposure. Finally, glutathione pool dynamics appears to be differentially affected by chromium species and concentrations. In conclusion, results of the present study have provided important information regarding the different activity profiles of Cr(III) and Cr(VI) in relation to kiwifruit pollen performance, and have also demonstrated differences in some biochemical responses of pollen to metal stress.
Scoccianti
Valeria
V
Istituto di Botanica, Università di Urbino Carlo Bo, Via Bramante 28, 61029 Urbino, Italy. valeria.scoccianti@uniurb.it
Iacobucci
Marta
M
Paoletti
Maria Filomena
MF
Fraternale
Alessandra
A
Speranza
Anna
A
D029042:Actinidia / Q000187:drug effects* / Q000254:growth & development; D002118:Calcium / Q000378:metabolism; D002857:Chromium / Q000378:metabolism*; D018525:Germination; D005978:Glutathione / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D018384:Oxidative Stress; D011058:Pollen / Q000187:drug effects* / Q000254:growth & development
D002857:Chromium; D005978:Glutathione; D002118:Calcium