PROLINE METABOLIC PATHWAYS IN CALLI FROM LYCOPERSICON-ESCULENTUM AND L-PENNELLII UNDER SALT STRESS

The enzyme activities of the proline metabolic pathways were determine d in control and salt-treated (140 M NaCl) calli derived from cotyledo ns of the domestic salt-sensitive tomato Lycopersicon esculentum and t he wild salt-tolerant L. pennellii. Glutamate, glutamine, asparagine, and aspartate levels increased in both genotypes under salt stress, wh ile proline accumulation increased markedly only in the salt sensitive tomato. Activity of glutamine synthetase (GS) decreased in the salt-t reated calli of the domestic species, whereas both NADH- and NADPH-glu tamate synthase (GOGAT) activities increased; GS and NADPH-GOGAT decre ased together in the salinized calli of the wild species. Decreasing o rnithine levels were found due to NaCl in both tomato populations, whi le ornithine transaminase (OT) decreased in the wild type only. Increa sing NADPH-A-pyrroline-5-carboxylate reductase (P5CR) and decreasing p roline oxidase (Pro oxi) occurred in the salinized calli of the wild t ype. Conversely, Pro oxi and proline dehydrogenase (Pro dH) decreased highly in the salinized calli of the domestic population, while no sig nificant changes in P5CR were found.