Salicylic acid mitigates hyperhydricity in newly developed potato shoots through reduced oxidation

Abstract

Hyperhydricity is a metabolic disorder of plants raised in tissue culture. In shoot cultures of potato (Solanum tuberosum L. ‘Atlantic’), hyperhydricity is induced by the synthetic cytokinin 6-benzylaminopurine (BA). Withdrawing BA from Murashige and Skoog (MS) medium and replacing it with salicylic acid (SA) restores lateral growth in mildly hyperhydric shoots. To evaluate the role of SA in reducing the extent of hyperhydricity in newly developed potato shoots, the physiological characteristics and enzyme activities of normal, hyperhydric, and SA-treated potato shoots were analyzed and compared. The results showed that the lower dose of SA (1 μmol·L−1) was more effective than the higher dose (100 μmol·L−1) at ameliorating the phenotypic and physiological characteristics of hyperhydric potato shoots. The SA-treated potato shoots did not significantly differ from normal potato shoots in term of phenotype and physiology. Oxidative stress in the hyperhydric potato shoots was alleviated by the SA-induced increases in free putrescine and spermine, glutathione, and increased activity of superoxide dismutase, catalase, and glutathione reductase, all of which were promoted by reactive oxygen species. The results also demonstrated that SA mitigates mild hyperhydricity and could help optimize potato propagation in tissue culture.