| dc.description.abstract | Sugars like glucose (Glc) can act as signaling molecules during plant development. Current
knowledge about sugar and abscisic acid (ABA) roles on physiology and key components
of involved signaling networks in higher plants has been obtained from studies mainly on
Arabidopsis thaliana plant model. However, the effect of these signals has been poorly
studied in lower plants like bryophytes. In order to determine the effect of Glc and ABA,
two developmental stages of the moss B. billarderi Schwägr was evaluated (spores and
protonemata) in mediums supplemented with different concentration of Glc and ABA.
Phenotypic and photosynthetic activity was scored in protonemata tissues and posible
effects on spores germination.
During 15 days of exposure of protonemata to Glc and Stl, phenotypic differences were
observed only at concentrations of 100 and 300 mM, showing a deeper green and greater
density in tissues exposed to these concentrations, compared to iso-osmotic control and
even control. At the highest concentrations we not observed protonemata phenotypic
differences between Glc and Stl, indicating that the phenotypes observed under these higher
concentrations are caused by the osmotic effect of Glc, which is accompanied by a total
inhibition of development and chlorotic appearance of the protonemata. Regarding
photosynthetic efficiency decrease in Glc at 500 mM in comparassion with sorbitol, we
observer that the photosynthetic efficiency decreases according the concentration of Glc or
Stl increases, however the photosynthetic efficiency in the iso-osmotic control shows a
slightly higher photosynthetic efficiency compared to glucose, suggesting that the osmotic
effect of Glc can be ruled out.
No phenotypic differences were observed in protonemata exposed during 15 days to
different concentrations of ABA, but in the photosynthetic efficiency it is possible to see
some differences. The protonemata exposed to Glc show lower photosynthetic efficiency
compared to protonemata exposed to iso-osmotic agent sorbitol, which indicates a clear
effect of glucose on the photosynthetic efficiency in this moss.
Spores germination in the moss B. billarderi Schwägr under Glc, Glc + ABA, Stl and
ABA+Stl conditions showed the effect of Glc on germination of spores, delaying germination from 300 mM, inhibiting germination in 500 mM, which does not occur with
iso-osmotic control, where germination still reaches 50% of germination. Phenotypes at the
post-germinating stage (two months 20 days), showing a clear effect of Glc and ABA on
the inhibition in the gametophores formation and a significant reduction in protonemata
development in medium with Glc, whereas this is not observed in iso-osmotic control
sorbitol.
Glucose acts as a signaling molecule on the development of protonemata and spores
germination of the moss P. cuspidatum, promoting tissue density and inhibiting spore
germination, (low and high Glc concentrations, respectively), ruling out the osmotic effect
concentrations generated by the differences found with iso-osmotic control. | |
