Abstract: Ethylene accumulation often occurs in plant tissue culture owing to limited gas exchange. The effect of silver thiosulfate (STS), an inhibitor of ethylene activity, on reducing ethylene-induced plant abnormalities was investigated in three diploid potato (Solanum tuberosum L.) genotypes (HS66, ED13, and DH401) with different concentrations (0, 1, 2, 4, and 8 mg L^-1) of STS in culture medium. The results showed that the leaf areas and total chlorophyll contents in three genotypes increased and aerial root could be eliminated by addition of 1 mg L^-1 STS into culture medium as compared with control (0 mg L^-1). Toxic symptoms like black purple pigment accumulation and callus occurring on leaf abaxial surface were observed on plantlets when the STS concentration was over 4 mg L^-1. The soluble protein, proline, and malondialdehyde (MDA) contents in three genotypes decreased first and increased then with the STS concentration increase. They declined in the medium containing 1 mg L^-1 STS compared with control. Addition of 2 mg L^-1 STS resulted in the ascending of soluble protein and proline contents in DH401 and MDA content in HS66. The soluble protein, proline, and MDA contents of three genotypes increased with STS concentration increasing in the medium containing 4–8 mg L^-1 STS. These results indicated that supplement of 1 mg L^-1 STS in medium could alleviate ethylene stress and improve plantlet growth. No morphological abnormality was observed in plantlets, but some physiological parameters showed STS toxicity to plantlets of HS66 and DH401 in the medium containing 2 mg L^-1 STS. Both morphological and physiological parameters indicated that higher concentration (4–8 mg L^-1) of STS in the medium was toxic to three genotypes in vitro.

Key words: Potato, Silver thiosulfate (STS), Plantlet growth, Physiological characteristics