IMPROVEMENT THE ADVERSE EFFECT OF SALT STRESS IN EGYPTIAN CLOVER (TRIFOLIUM ALEXANDRINUM L.) BY AsA APPLICATION THROUGH SOME BIOCHEMICAL AND RT-PCR MARKERS

The present study was carried out to examine whether exogenously applied ascorbic acid (AsA) may mitigate the deleterious effect of salt stress in Egyptian clover (Trifolium alexandrinum L.). Three weeks old seedlings, grown in half strength MS medium, supplemented with 0.0, 50, 75 or 100 mM NaCl or 1.0 mM ascorbic acid and the combination between them, were harvested and the various measurements were recorded. Addition of AsA to the NaCl medium significantly, improved seed germination, dry mass, as well as chlorophylls and carotenoid contents. Also, application of AsA in the culture medium alone or in combination with salt treatments increased the content of proline. Additionally, semi-quantitative reverse transcription-PCR (RT-PCR) enabled to determine transcript levels of each of the pyrroline-5-carboxylate synthetase (P5CS), delayed-response (RD29) and alcohol dehydrogenase (ADH) genes. The results showed that, there were changes in the expressions level of RD29, ADH and P5CS genes under salinity stress compared with control. The results revealed that salt-induced deleterious effect in Egyptian clover seedlings and could be alleviated by AsA treatment. Moreover, AsA can be used as a signal molecule to investigate plant defense to salt stress.