The present paper describes multiple splicing types of OsRIX4,an RAD21 homolog in rice. A type of alternative splicing (AS),distinctive from all five previously known splicing types,was identified in which interior sequences of a constitutive exon could be spliced. Translation of the transcript produced with this AS type was demonstrated at the protein level. Expression of multiple transcripts was organ specific. The expression abundance of transcripts,OsRIX4-4 and OsRIX4-5,was positively correlated with fertility in rice. The splicing type identified in the present study provided the means to further un-derstand and define different mRNA splicing types in plants and suggested that post-transcription processing of mRNA and its regulation mechanism are complex.
