RESUMO
In vitro preservation of transgenic tomato lines overexpressing the stress-responsive transcription factor SlAREB1 was studied by using slow growth and cryopreservation techniques. Slow growth preservation was performed by using different concentrations of sucrose (0, 100, 200, 300 mm) and abscisic acid (0, 4, 8, 12 µm) in Murashige and Skoog (MS) media, while cryopreservation was conducted by using encapsulation dehydration, V-cryoplates and seeds. Significant differences were observed between tested lines grown on MS media supplemented with 200 mm sucrose where transgenic lines overexpressing SlAREB1 showed improved growth when compared with negative control. The addition of abscisic acid (ABA) to the preservation media affected negatively transgenic lines growth and development when compared with ABA-free media. In encapsulation dehydration, non-cryopreserved transgenic lines overexpressing SlAREB1 pretreated in 0.8 M sucrose for 1 day and subjected to different dehydration periods showed significantly higher survival percentages when compared with negative control. For V-cryoplates technique, cryopreserved transgenic lines overexpressing SlAREB1 treated in 0.3 M sucrose for 3 days with or without cold acclimatization showed significantly higher survival percentages when compared with the negative control. Seed cryopreservation was performed successfully with a clear reduction in germination percentage in transgenic lines overexpressing high levels of SlAREB1. In conclusion, transgenic tomato lines overexpressing SlAREB1 were found to improve tolerance against different abiotic stresses associated with different in vitro preservation protocols.
