Constitutive over-expression of Osmotin improves seed germination under salt and osmotic stress in transgenic tomato (Solanum lycopersicum L. cv. Pusa Ruby)

Transgenic tomato (Solanum lycopersicum L. cv. Pusa Ruby) was developed through constitutive over expression of Nicotiana tabacum Osmotin gene. Our earlier studies have validated improved cold tolerance in the transgenic tomato. The present study reports salt and osmotic stress responses in the transgenic tomato at germination stage. Transgenic and wild type tomato seeds were placed for germination in presence of salt (NaCl; 0, 100, 150, 200 mM) or polyethylene glycol induced osmotic stress (PeG 6000; 15, 20%). The seed performance in terms of germination and seedling establishment under control (non-stressed) condition was significantly (P ≤ 0.05) improved in the transgenic (99.0 ± 1.6%) than the wild type (60.0 ± 1.6%). Higher and rapid germination was recorded in the transgenic seeds than that in the wild type in presence of 150 mM NaCl. Germination in wild type seeds was completely inhibited in presence of higher (200 mM) salt concentration whereas 9.0 ≤1.6% transgenic seeds germinated successfully. Under polyethylene glycol (PEG 6000, 20% w/v) induced osmotic stress, significantly higher and rapid seed germination was observed in the transgenic than the wild type. The present study reports salt and osmotic stress tolerance through constitutive over expression of Osmotin at seed germination in tomato.