References

244 V. Demidchik
transients were blocked by inhibitors of animal purinoceptors (suramin
and pyridoxalphosphate-6-azophenyl-2 ′ ,4 ′ -disulfonic acid) (Demidchik et
al. 2003). Overall, these data suggest that plants evolved systems for purine
signalling which are very similar to animal purinoceptors.
16.6
The Role of NSCC in Plant Growth and Development
Despite a number of observations showing the indirect involvement of
ligand-gated NSCC (reviewed by Davenport 2002; Talke et al. 2003) in plant
growth and development, data demonstrating direct evidence for such
involvement are very limited (Demidchik et al. 2002, 2003; Foreman et al.
2003). It was shown that elongation of cells in the elongation zone and
elongation of root hairs is driven by an ROS/Ca 2+ -dependent mechanism
that is mediated by plasma membrane NADPH oxidase and ROS-activated
Ca 2+ -permeable NSCC (Demidchik et al. 2003; Foreman et al. 2003). In
addition, constitutive NSCC were shown to have higher activity in the root
elongation zone that could promote further [Ca 2+ ]cyt elevation through
activation of HACC (Demidchik et al. 2002).
16.7
Conclusions and Future Perspectives
Our understanding of physiological roles of NSCC has significantly progressed
in the last few years. Apart from toxic Na + influx, this group of
channels was shown to be involved in nutritional uptake of K + ,NH + 4 ,Ca2+ ,
Mg 2+ , micronutrients and trace elements, in ROS-, amino acid, purine- and
cyclic nucleotide induced signalling, growth and development. The next
step in studying NSCC will be the delineation of their involvement in communication
between plant cells, and between plants and other organisms.
Another important task for future research is to find genes encoding plant
purinoceptors, ROS-activated NSCC and constitutive NSCC.
References
Amtmann A, Laurie S, Leigh RA, Sanders D (1997) Multiple inward channels provide
flexibility on Na + /K + discrimination at the plasma membrane of barley suspension
culture cells. J Exp Bot 48:481–497
Apel K, Hirt H (2004) Reactive oxygen species: metabolism, oxidative stress, and signal
transduction. Annu Rev Plant Biol 55:373–399