Enhancement of cyanobacterial salt tolerance by combined nitrogen

Reddy, Bontha R. ; Apte, Shree K. ; Thomas, Joseph (1989) Enhancement of cyanobacterial salt tolerance by combined nitrogen Plant Physiology, 89 . pp. 204-210. ISSN 0032-0889

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Official URL: http://www.plantphysiol.org/cgi/content/abstract/8...


Presence of certain nitrogenous compounds in the growth medium significantly enhanced the salt tolerance of the fresh-water cyanobacterium Anabaena sp. strain L-31 as well as the brackish water cyanobacterium Anabaena torulosa. Among these, nitrate, ammonium, and glutamine were most effective followed by glutamate and aspartate. These nitrogenous compounds also inhibited Na+ influx in both Anabaena spp. with the same order of effectiveness as that observed for protection against salt stress. The inhibition of Na+ influx on addition of the nitrogenous substances was rapid; nitrate and ammonium inhibited Na+ influx competitively. Proline and glycine did not affect Na+ influx and also had no influence on the salt tolerance of either Anabaena sp. The observed protection was not consequent to a stimulatory effect of combined nitrogen on growth per se. Uptake of NO3- and NH4+ increased during salt stress but was not correlated with growth. Intracellular levels of NO3- and NH4+ were found to be inadequate to constitute a major component of the internal osmoticum. The results suggest that inhibition of Na+ influx by combined nitrogen is a major mechanism for protection of cyanobacteria against salt stress.

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Source:Copyright of this article belongs to American Society of Plant Biologists.
ID Code:766
Deposited On:25 Sep 2010 04:46
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