Alternative splicing of the -like gene is associated with endodormancy in mulberry.

Alternative splicing (AS) is an important post-transcriptional process that generates multiple mRNA isoforms. () is a pivotal gene in both the vernalization and autonomous pathways of flowering plants, and is one of the homologs in white mulberry (). Recent studies have revealed that is involved in endodormancy, but the underlying molecular mechanism remains to be characterized. Here, a comparison of expression among three mulberry cultivars with different degrees of dormancy revealed a positive association between expression and dormancy. Further 3' and 5' rapid amplification of cDNA ends (RACE) analyses led to identifying four isoforms derived from AS and designated -. Analysis of their coding potential revealed that was a long non-coding RNA. Expression profiling and splicing-efficiency analyses showed that cold stress during endodormancy induced AS of , resulting in a predominance of truncated isoforms, especially . expression was upregulated during both endodormancy and ecodormancy, whereas and were endodormancy-associated isoforms that were upregulated during endodormancy and then downregulated during ecodormancy. MaMADS33-AS4 was used as bait for a yeast two-hybrid screen because its gene expression was higher than that of MaMADS33-AS3, and mulberry winter-accumulating 18 kDa protein (MaWAP18) was identified as an MaMADS33-AS4 interaction partner. The interaction between MaWAP18 and MaMADS33-AS4 was confirmed by a bimolecular fluorescence complementation assay. These findings offer insight into the role of homologs in the endodormancy of woody plants.