Expression of an engineered cysteine proteinase inhibitor (Oryzacystatin-IΔD86) for nematode resistance in transgenic rice plants

We have used a genotype-independent transformation system involving particle gun bombardment of immature embryos to genetically engineer rice as part of a programme to develop resistance to nematodes. Efficient tissue culture, regeneration, DNA delivery and selection methodologies have been established for elite African varieties ('ITA212','IDSA6', 'LAC23', 'WAB56-104'). Twenty-five transformed clones containing genes coding for an engineered cysteine proteinase inhibitor (oryzacystatin-I Delta D86, OC-I Delta D86), hygromycin resistance (aphIV) and beta-glucuronidase (gusA) were recovered from the four varieties. Transformed plants were regenerated from all clones and analysed by PCR, Southern and western blot. Detectable levels of OC-I Delta D86 (up to 0.2% total soluble protein) in plant roots were measured in 12 out of 25 transformed rice lines. This level of expression resulted in a significant 55% reduction in egg production by Meloidogyne incognita.