Influence of salinity on the morphogenic response of hypocotyl explants of tomato (Lycopersicon esculentum Mill.)

Abstract

This experiment assessed the in vitro response of hypocotyl explants of tomato variety (KC-1) to salinity stress. Hypocotyl explants were taken from in vitro grown 12 days old seedlings used as explants in this experiment. The different portions of hypocotyl explants from in vitro grown seedlings and inoculated on Murashige and Skoog media fortified with 1.5 mg/L 6-Benzylaminopurine, 0.2 mg/L 1- Naphthaleneacetic acid and different concentrations of NaCl salt. It was observed that the morphology of the cultured hypocotyl was significantly different (p<0.05) from the salt and control culture media. Moreover, the results revealed that in hypocotyl explants, the different portions exhibited different responses to the salinity. The top portion of hypocotyl explants produced micro shoots directly, while the bottom portion of hypocotyl explants formed callus from the cultured explants. Four weeks after the establishment of culture, the fresh weight and callus colour was recorded, and it was compared with the salt-free media, which showed a significant difference in each portion of explant. When the salinity concentration increased, there was a significant decline in the in vitro response up to 4 weeks of culture. The top portion of hypocotyl produced shoots from the 35 mM salt media but with distinct necrotic patches. The fresh weight of callus was higher in the 15 mM salt media than in the control media and tended to produce shoots after transferring into a salt-free media.