Vegetative winter buds of pear (Pyrus communis L. cv. Beurre d'Amanlis) were successfully cryopreserved at -150 °C after pre-freezing to -30 °C. Meristems were excised from the buds and cultured on medium (WPM) containing 1.0 mg-liter-1 6-benzylamino-purine (BA), 25 g-liter-1 sucrose and 0.8% (w/v) agar. Partial dehydration at 25 °C prior to pre-freezing at - 30 °C improved the subsequent shoot formation rate. The optimal water content of the dehydrated buds was about 41%. Pre-freezing with a daily decrease at 5 °C increments to -30 °C followed by slowly thawing in air at 0 °C was effective for producing the highest rate of shoot formation. Micrografting of the cryopreserved vegetative buds on young seedlings also induced normal shoot growth. This procedure was successfully applied to twelve other cultivars of pear. Thus, this protocol of using vegetative buds is a simple, reliable method for cryopreserving pear germplasm.
Japanese Society for Horticultural Science