Improving Salt Tolerance of Zea Mays L. Plants by Presoaking Their Grains in Glycine Betaine.

2 Absatract: The present investigation was carried out to study the effect of post-emergence soil treatment with different salinity levels (50, 100, and 150 mM NaCl) on growth characteristics, 3 endogenous phytohormones (IAA, GA , zeatin, zeatin riboside, ABA and ethylene), photosynthetic pigments, carbohydrate contents, mineral ions composition, total amino nitrogen and proline, total soluble protein and protein profile of 30-day old Zea mays L. plants cv. Giza 2 resulted from grains soaked in water or the osmoprotectant glycine betaine for 12 hours at 28°C ± 2. Glycine betaine was shown to improve salt tolerance in Zea mays L. cv. Giza by protecting endogenous phytohormones from damage induced by salinity stress. It is able also to improve the vital properties of stressed Zea mays plants through protecting chloroplast membrane, preserving photosynthetic pigments, enhancing osmotic adjustment and turgor maintenance by accumulating organic osmolytes (total amino nitrogen, proline, total soluble protein and total soluble sugars) and inorganic osmolytes (K , M g and Ca ions). Glycine betaine was shown also to enable Zea mays plants to cope with salinity via alteration of gene expression which led to the appearance of new proteins and / or increased the intensities of the other that may be involved in increasing the tolerance of Zea mays plants.