Strigolactone (GR24) Induced Salinity Tolerance in Sunflower (Helianthus annuus L.) by Ameliorating Morpho-Physiological and Biochemical Attributes Under In Vitro Conditions

Strigolactone (GR24) is a phytohormone, involved in reconfiguration of plant development pattern in response to salinity stress. Current experiment was carried out in vitro conditions to study the role of GR24 on sunflower (Helianthus annuus L. cv. OLIVER-P) under saline and non-saline growth mediums. Two salinity levels [0 mM (control) and 150 mM NaCl] were maintained in growth mediums for callus induction along with four GR24 levels (0, 0.001, 0.01, 0.1 mg L-1) in Somatic Cell Genetic Lab, Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture Faisalabad, Pakistan. Results of this study showed that among GR24 levels, 0.01 mg L-1 proved to be ideal dose as it improved callus fresh weight (30.59%), dry weight (45.26%), free protein (55.87%), Ca2+ (13.04%) and K+ (11.76%) contents under non-saline, while superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), free proline and glycine betaine (GB) contents by 38.1%, 67.87%, 124.01%, 63.38% and 76.12%, respectively, under salinity stress mediums. However, water potential (psi w), osmotic potential (psi s), turgor potential (psi p), hydrogen peroxide (H2O2) and malondialdehyde (MDA) were reduced up to 32.65%, 39.80%, 40.74%, 65.78% and 30.76%, respectively, due to different levels of GR24. Overall, high saline conditions caused a significant reduction in concentration of callus biomass, psi w, psi s, soluble protein, Ca2+ and K+ ions than non-saline mediums. These results reflected that GR24 application could be an effective approach to mitigate hazardous impacts of salinity in sunflower production. Further, the molecular techniques of processes in which GR24 may play a key role in different commercially vital crops is extreme important and may carry new leads for future experimentation in this exciting area of plant hormones.