KIWIFRUIT LEAF PROTOPLASTS COMPETENT FOR PLANT-REGENERATION AND DIRECT DNA TRANSFER

Leaves of kiwifruit cv. Hayward micropropagated plantlets were used as a source of protoplasts for direct DNA transfer and plant regeneratio n. Leaf preculture for 5-6 days on a medium containing zeatine (S') wa s found to improve the yield of viable protoplasts. An efficient purif ication method-is described which is easy to perform and yields two pr otoplast populations that differ in both transient expression and rege neration ability. One population consisted of hyaline or light green p rotoplasts originating from epidermis and leaf veins, the other consis ted of green protoplasts very dense in chloroplasts and originating fr om mesophyll. Cell division and plant regeneration could only be obtai ned from the former population. This same population was also found to efficiently express the GUS reporter gene introduced by direct DNA tr ansfer. These results prove that it is possible to use kiwifruit leave s directly for protoplast isolation and that the selected protoplast p opulation should be regarded as an alternative source of protoplasts c ompetent for both plant regeneration and transient gene expression. Co pyright (C) 1996 Elsevier Science Ireland Ltd.