In vitro selection and molecular characterization of salt tolerant canola plantlets

In this study, a system for in vitro selection of salt tolerant canola clones [plantlets] was developed. The developed system relies on somaclonal variation and the high regenerative capacity of hypocotyl explants of the Egyptian canola cultivar Serw 4 via direct and indirect shoot organogenesis. The optimized regeneration system involves callus formation from hypocotyl explants of 4 day-old seedlings on MS medium supplemented with 1.5 mg/l 2,4-D and shoot proliferation from proliferated microcalli colonies on MS + 4.0 mg/l BA. Shoot organogenesis frequecny ranged from 35 to 40%. This system was used for in vitro selection of salt tolerant plantlets from hypocotyl explants of seedlings germinated on salt containing medium. Under selection pressure, shoot organogenesis frequencey dropped to 5% for selected cell lines and zero for non-selected cell lines onto 0.3% NaCl. The biochemical and molecular characterization of the selected and non-selected clones were performed using: proline accumulation, total protein content, SDS-PAGE and RAPD analysis. The salt-tolerant plantlets were characterized by improved growth on saline media, rapid accumulation of proline, high content of total protein, synthesis of new set of high molecular weight proteins [38 and 94 KD] and unique RAPD banding profiles. The criteria of the selected clones outlined above may be a part of biochemical make up performed by these canola clones to tolerate extreme salt stress

Synthesis of thiaphosphetane, thiadiphosphetane and thiazadiphosphetidine derivatives from the reaction of phosphacumulenes, phosphallene and phosphinimine with Lawesson's reagent

The active phosphacumulene ylides namely, N-phenylimino-[2], 2-oxo- [4] or 2-thioxo-vinylidenetriphenylphosphorane [6] are nucleophilic reagents which can be considered as versatile synthons for the synthesis of new heterocycles. They react with Lawesson's reagent [1] to give the corresponding thiaphosphetane derivatives 3, 5 and 7 respectively, which constitute an important class of heterocyclic compounds with medicinal and biological importance. On the other hand, Lawesson's reagent [1] can be converted by reaction with the active heteroallylic phosphonium ylide, hexaphenylcarbodiphosphorane [8], into the thiadiphosphetane 9. When the phosphinimine 10 reacts with Lawesson's reagent [1], the thiazadiphosphetidine 11 was obtained