Effect of salicylic acid on betaine aldehyde dehydrogenase gene expression in potato (Solanum tuberosum L., cv. Agria) under salinity stress

Introduction Potato (Solanum tuberosum) is an important crop in tropical countries. Salinity stress is the crucial factor that seriously limits agricultural production in various regions especially in arid and semi-arid areas. Salicylic acid is a bioactive molecule that synthesizes via enzymatic and non-enzymatic pathways under stress conditions in different organs of plant, regulates and adjustments defense reactions of plant. Salicylic acid (SA) is known as a signalling molecule that modifies plant responses to pathogen infection. Many studies have shown that this compound can protect plant under oxidative stresses and maintain chlorophyll. In addition to being an important component of biotic stress tolerance mechanism, SA also regulates various aspects of plant responses to abiotic stresses through extensive signalling cross-talk with other growth hormones. However, exact mechanisms by which SA protects plants during abiotic stresses remain obscure. Salinity stress is the crucial factor that seriously limits agricultural production in various regions especially in arid and semi-arid areas. Salicylic acid is a bioactive molecule that synthesizes via enzymatic and non-enzymatic pathways under stress conditions in different organs of plant, regulates and adjustments defense reactions of plant. Salicylic acid (SA) is known as a signalling molecule that modifies plant responses to pathogen infection. Many studies have shown that this compound can protect plant under oxidative stresses and maintain chlorophyll. In addition to being an important component of biotic stress tolerance mechanism, SA also regulates various aspects of plant responses to abiotic stresses through extensive signalling cross-talk with other growth hormones. However, exact mechanisms by which SA protects plants during abiotic stresses remain obscure. Material and methods This experiment was conducted at the plant tissue culture laboratory of Horticultural Sciences, Department, University of Tabriz, Iran, during spring–summer of 2017. The present study was aimed to investigate of salicylic acid effect on betaine aldehyde dehydrogenase gene expression and glycine betainesynthesis in Solanum tuberosum cv. Agria under salinity stress on in vitro condition. The experiment treatments included four level of salycilic acid (0, 1, 10 and 100 mM) and two level of sodium chloride (0 and 70 mM). In the present study, MS media culture was used and sodium nitroprusside was applied for increasing the betaine aldehyde dehydrogenase gene expression (the responsible gene of glycine betaine synthesis) under salinity stress. Four weeks after treatment, total RNA of treated explants was extracted and semi quantitative RT-PCR was used for the analysis of expression of betaine aldehyde dehydrogenase gene. Results and semi quantitative RT-PCR was used for the analysis of expression of betaine aldehyde dehydrogenase gene. The glycinbetainecontent was measured with iodide potassium. The survey of betaine aldehyde dehydrogenase gene expression showed increased under salinity stress. Also salicylic acid increased the glycine betaine content in grown plantlets which were grown under normal condition.The expression pattern of glycine betain gene showed tha by increasing of salicylic acid and sodiuom chloride concentration the expression of glycine betain gene has been increased in all samples. however under salinity stress this compound showed negative effect on glycinbetaine content. Conclusion In conclusion, antioxidant activity, total phenol and protein were increased salinity stress. In addition, antioxidant activity and glycine betaine content during salt stress period was decreased application of nitric oxide. The glycine betaine content of plantlets in general condition with application of sodium Salicylic acid increased but under salinity stress, Salicylic acid had negative effect on glycine betaine content. The results of this research showed that exogenous application of salicylic acid increased the expression level of genes and lead to enhancement of plant tolerance to salinity stress. Further studies are necessary to determine optimum concentration and duration of Salicylic acid application in order to achieve maximum benefit in Solanum tuberosum tissue culture.