Haemoglobin-Enhanced Mitosis in Cultured Plant Protoplasts

Abstract

Potato (Solanum tuberosum) is the world’s fourth most economically important food crop, following wheat, rice and maize. Potato breeding is slow compared to that of other major crops, making it an important candidate for in vitro genetic manipulation involving direct gene transfer into isolated protoplasts (‘naked cells’, from which the walls have been removed by enzymatic digestion), and somatic hybridisation or cybridisation. Both of the latter techniques are based on the fusion of protoplasts from potato with those of other Solanum species. A pre-requisite for such investigations is reproducible growth in culture of protoplasts to cells, followed by the differentiation of protoplast-derived tissues into fertile plants. An adequate and sustainable oxygen supply is a fundamental requirement to maximise growth of protoplasts and protoplast-derived cells. Previous studies have demonstrated the beneficial effects of medium supplementation with the chemically-modified haemoglobin (Hb), Erythrogen ^TM,on mitotic division of protoplastderived cells and subsequent plant regeneration in Oryza sativa (Azhakanandam et al., 1997; Al-Forkan et al., 2001), Passiflora giberti and Petunia hybrida cv. Comanche (Anthony et al., 1997). However, there have been no corresponding studies with major dicotyledonous crops, such as potato.