CONDITIONS OF CALLUS-CULTURE FROM THE FOLIAGE OF MATURE CRYPTOMERIA-JAPONICA - KINDS OF BASAL MEDIA, GROWTH-REGULATORS AND OPTIMAL TIMING FOR COLLECTING EXPLANTS IN YAMAGATA-PREFECTURE

Growth of calli from the apical meristems or leaves of mature Cryptome ria japonica D. Don was investigated using 1% agar media containing fo ur kinds of basal nutrients, eight kinds of auxins with or without BA at 25-degrees-C in the dark. The results indicated that the medium of MS basal nutrients, 3% sucrose, and 2 ppm of NAA was superior to the o thers. Although co-existence of BA promoted callus growth, the relativ e order in effectiveness among the auxins was unchanged. The calli ini tiated from the apical meristems of triploid strains generally propaga ted more vigorously than did the diploids among the 18 clones examined . The optimal explants for callus preparation were obtained from the a pical meristems of foliage in late autumn and early spring and the tis sues obtained in other seasons were unsuitable because of infection by fungi. Observations by SEM and investigation of peroxidase isozymes b y PAGE indicated that the rapidly propagated calli had the larger size cells and intense isozyme bands in comaprison with the poorly propaga ted ones. Thus, the durability of auxins against action by peroxidase in tissue would be most important for the callus culture of mature C. japonica foliage.