In vitro plant regeneration of Zelkova schneideriana, an endangered woody species in China, from leaf explants.

摘要

Zelkova schneideriana Hand.-Mazz. is a high-value plant used for hardwood timber production in China. Because of over-harvesting and limited numbers of seedlings for plantations, Z. schneideriana has become an endangered species in China. To grow this plant sustainably, we generated a protocol to reproduce this species using tissue culture. Leaf explants were cultured on Wood Plant Medium (WPM), Murashige and Skoog (MS), 1/2MS (main elements), or B5 media variously supplemented with 6-benzylaminopurine (BA), naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), or 2, 4-dichlorophenoxyacetic acid (2,4-D) to induce callus, adventitious shoots, and rooting. WPM was the most effective medium for callus induction and resulted in two types of calli from leaf explants. One was soft and straw-yellow coloured on WPM containing 0.45, 4.54, 9.08, or 13.62 micro M 2,4-D or on WPM supplemented with 4.44 micro M BA in combination with 0.45 or 4.54 micro M 2,4-D. The other callus type was friable and green on WPM supplemented with 0.44, 4.44, 8.88, or 13.32 micro M BA or on WPM supplemented with 4.44 micro M BA in combination with 0.54 or 5.37 micro M NAA. Only the latter callus type was observed to regenerate plantlets. WPM supplemented with 4.44 micro M BA plus 2.68 micro M NAA had a 64.5% shooting rate, with 6.75 shoots per callus. Rooting at 70.0%, with an average of 3.6 roots per shoot, was obtained on WPM supplemented with 2.46 micro M IBA in combination with 2.0 g l-1 activated charcoal (AC). In total, 86% of regenerated Z. schneideriana plantlets survived after acclimation in a greenhouse at 24 degrees +or-2 degrees C under a 16 h photoperiod provided by cool-white fluorescent lights (PPFD=65.5 micro mol m-2 s-1), and 100% survived after transplanting to an experimental field plot.