<Original>Morphological Observation of the Calli derived from Four Coniferous Species in vitro

Abstract

Callus tissues were derived in vitro from four coniferous species (Cryptomeria japonica, Pinus thunbergii, Ginkgo biloba and Sequoia sempervirens) and the morphological features of the calli were discussed in relation to their growth rates. Xylem and phloem cells differentiated in the calli but these cytodifferentiations were not correlated to growth rate of the calli. On the other hand, the following tissue organizations were correlated to growth rate. High growth rate calli showed a loose intercellular contact and formed no dermal tissue, whereas low growth rate calli formed tight tissues covered with dermal tissues. All calli formed vascular nodules which were categorized into three types, i.e. circular, linear and continuous types. The first one was predominant in high growth rate calli, the frequency of the second one increased as the growth rate became lower, and the third one was formed in the calli which grew extreamly slow. The correlation between tissue organizations and growth rate might be common among species, and the former is controlled by the latter