The modified castor bean catalase intron is incompletely spliced in tobacco and Arabidopsis

► We constructed an intron-containing Cre recombinase gene, iCre. ► The modified castor bean catalase (mCBC) intron placed in the iCre gene was incompletely spliced. ► The mCBC intron was also incompletely spliced from the Gus gene in pCAMBIA vectors. ► The incomplete splicing was caused by an artificially created 3′ splice site. ► Complete splicing of the mCBC intron was achieved either by deleting an introduced adenine or by deleting the six unspliced nucleotides.