The level of mRNA NAD-SDH is regulated through RNA splicing by sugars and phytohormones

Unspliced (L-SDH) and spliced (S-SDH) transcripts of NAD+-dependent sorbitol dehydrogenase (NAD-SDH) of strawberry (Fragaria ananassa Duch., cv. Nyoho) were investigated. Fructose, mannitol, and IAA increased S-SDH transcript level. Sorbitol decreased the level of L-SDH transcript 2.5-fold. ABA and bensyladenin (BA) decreased S-SDH thanscript level and increased L-SDH transcripts. Ratio of S-SDH to L-SDH was increased by sorbitol (2.7-fold), fructose (2.2-fold), IAA (1.5-fold), and decreased by BA (4-fold) and ABA (1.7-fold) as compared to control. These results suggest that sorbitol, fructose, and IAA stimulated splicing of pre-mRNA NAD-SDH, but BA and ABA repressed this process.