A Convenient Method for Exposing Shoot Apical Meristems Using Compressed Air

Exposing the shoot apical meristem (SAM) is necessary in horticultural practices such as shoot tip culture, colchicine treatment, gene transfer, and so on. However, ordinary methods of exposing SAMs require extensive training and are labor-intensive. We developed equipment to expose SAMs quickly and easily by blowing compressed air on the shoot tips. Using this equipment allowed SAMs to be exposed more rapidly than the ordinary methods. Exposure time was shortened from 27.8 s to 7.4 s, 15.7 s to 7.9 s, and 59.7 s to 6.8 s in chrysanthemum (Chrysanthemum morifolium), dahlia (Dahlia spp.), and Lilium leichtlinii, respectively. To determine whether blowing compressed air caused injury to SAMs, we used shoots in which the SAMs had been already exposed and observed resin sections of SAMs that had been subjected to the additional compressed air treatment for several seconds. Results showed that blowing additional compressed air for as long as 9 s did not injure SAMs. Using this equipment, we can expose SAMs without using a stereomicroscope by blowing compressed air to the top of shoots for several seconds. Over 70% of SAMs could he exposed in a 7- to 13-s blowing treatment without injury. We could successfully use this equipment in shoot tip culture and leaf primordia-free SAM culture.