PLANT-REGENERATION FROM CALLUS-CULTURES OF SALT-MARSH HAY, SPARTINA PATENS, AND ITS CELLULAR-BASED SALT TOLERANCE

Salt marsh hay, Spartina patens (Ait.) Muhl. (Poaceae),is a perennial salt-tolerant grass common in salt marshes and sand dunes of the Atlan tic and Gulf coasts of the USA, and grows vigorously at coastal seawat er salinity. To study the salt tolerance mechanisms that operate in S. parens at the cellular level, a tissue culture and regeneration proto col for this species was developed, Callus was initiated from seeding mesocotyl on ADM medium (Murashige and Skoog (MS) salts + 3% sucrose 1 mg 1(-1) indoleacetic acid (IAA) and 1 mg 1(-1) 2,4-dichlorophenoxy acetic acid (2,4-D)). Regenerable callus was selected from the several morphotypes that developed and was maintained on END medium (MS salts + 3% sucrose + 0.5 mg 1(-1) 6-benzylaminopurine (BAP), 1 mg 1(-1) 1-n aphthaleneacetic acid (NAA), 0.5 mg 1(-1) 2,4-D, and 50 mi 1(-1) cocon ut water (CW)). Shoots formed from 90% of the cultures grown on shoot regeneration medium containing BAP and IAA. Roots formed from shoots w hen they were transferred to root regeneration medium containing indol e-3-butyric acid (IBA) and activated charcoal or reduced strength MS m edium. Plants regenerated via organogenesis have flowered and set viab le seeds in a saltwater-irrigated field plot. Dry weight accumulation of unadapted callus at 510 mM NaCl is similar to that at 0 mM NaCl (co ntrol), indicating that S. patens has strong salt tolerance at the cel lular level.