The effect of Rosmarinic acid on glycine betaine, carbohydrate and protein pattern changes of potato (Solanum tuberosum L.) callus under in vitro condition

Salt stress is one of the most destructive abiotic stress which affects compatible osmolytes and protein pattern. In the current study, the effect of rosmarinic acid as a polyphenolic quencher on compatible solutes such as glycine betaine, total carbohydrates and protein, Na+ and K+ and fresh weight were determined to evaluate osmotic adjustment as a stress tolerance mechanism in Solanum tuberosum L. c.v. White Desire in vitro condition. In the other experiments, SDS-PAGE was performed to verify feasible hypothesis of ameliorative effects of RA on biosynthesis of proteins. In vitro-grown cells of potato were incubated on Murashige and Skoog (MS) medium containing 0, 20, 40, and 60 mg/L RA and 0, 90, and 120 mM NaCl. Data showed increase in fresh weight in 120 mM-stress calli pretreated with rosmarinic acid compare to 120 mM stressed calli. Carbohyadrate content increased notably by using RA in exposure to NaCl. The results showed a significant increase in glycine betaine in 90 mM NaCl +20 mg/L RA treated calli compared with 90 mM NaCl-stressed calli. There was a notable increase in contents of Na+ and decline in K+ content in in vitro calli cells grown under 90 and 120 mM salt levels. Interestingly, K+ contents in RA-treated calli cells were remarkably higher than Na+ contents. However, no pronounced changes in K+/ Na+ ratio were observed. Data showed that in vitro RA-treated calli responded rapidly to external RA supplement showing higher proteins contents compared to controls. SDS-PAGE data indicated a positive impact of RA on protein pattern. In vitro calli cells treated with 20 and 60 mg/l RA showed the induction of 2 new protein bands with approximately 50 KD while, 3 protein bands with approximately 16, 17 and 25 KD were down-regulated by RA. Consequently, data presented in the current study indicated a positive link between salt tolerance and improved metabolites biosynthesis in potato White Desire following RA treatment.