Sodium nitroprusside promotes multiplication and regeneration of Malus hupehensis in vitro plantlets

The effects of sodium nitroprusside (SNP) on the multiplication, regeneration and rooting of Malus hupehensis Rehd. var. pinyiensis Jiang in tissue culture have been investigated. The results showed that the multiplication of plantlets was promoted significantly by applying 20 mu M SNP to the Murashige and Skoog (MS) medium containing 2.0 mu M 6-benzylaminopurine (BA) and 1.0 mu M zeatin (ZT). Multiplication of plantlets from the 1st subculture was more sensitive to SNP than that from the 4th or 7th subculture. The differentiation and regeneration of adventitious shoots from leaves or cotyledons increased significantly when 20-30 mu M SNP was supplied to the medium MS containing 25 mu M BA, 2.5 mu M alpha-naphthaleneacetic acid (NAA) and 2.5 mu M ZT. Adventitious shoots regeneration frequency from cotyledons was higher than that from leaves at the presence of SNP. The rooting of plantlets was promoted by SNP significantly and the best result for rooting was achieved in the half-strength MS medium containing 75 mu M SNP. In addition, adventitious roots without callus distributed at the base of shoots when SNP was supplied.