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DIFFERENCE IN COMPETENCE FOR IN VITRO PROLIFERATION AND EX VITRO GROWTH OF GENETICALLY IDENTICAL MATURE AND JUVENILE CLONES OF APOMICTIC MALUS SPECIES

HAFEEZ-UR-RAHMAN, D. J. JAMES^*, P.D.S. CALIGARI^** AND A. WETTEN^**

Abstract: The apomictic system in Malus was used as a model to examine rejuvenation by generating genetically identical tissue culture lines that had two entirely different developmental origins: either embryo-derived tissues (juvenile clones) or somatic tissue from the adult/mature tree (mature clones). These two lines were then subsequently used to examine in vitro difference between mature (M) and juvenile (J) tissues in potential for shoot, root proliferation and ex vitro (glasshouse) growth. The M clones of M. hupehensis and M. toringoides in vitro had significantly fewer total shoots and shoot more than 2 cm in length per proliferating explant than the J clones and also rooted less efficiently. Ex vitro (glasshouse) juvenile clones had shorter internodes, a greater number of leaves and more dry weight compared to their mature counterparts.

Fruit Crops, National Agricultural Research Centre (NARC), Islamabad, Pakistan

^*Horticulture Research International, East Malling, West Malling, Kent ME19  6BJ,  UK.

^**Department of Agricultural Botany, The University of Reading, Whiteknights Reading RG6  6AS, UK.