Abstract: Autopolyploid plants and their organs are often larger than their diploid
counterparts, which makes them attractive to plant breeders. Mulberry (Morus alba L.) is
an important commercial woody plant in many tropical and subtropical areas. In this
study, we obtained a series of autotetraploid mulberry plants resulting from a colchicine
treatment. To evaluate the effects of genome duplications in mulberry, we compared the
phenotypes and transcriptomes of autotetraploid and diploid mulberry trees. In the
autotetraploids, the height, breast-height diameter, leaf size, and fruit size were larger than
those of diploids. Transcriptome data revealed that of 21,229 expressed genes only
609 (2.87%) were differentially expressed between diploids and autotetraploids. Among
them, 30 genes were associated with the biosynthesis and signal transduction of
plant hormones, including cytokinin, gibberellins, ethylene, and auxin. In addition,
41 differentially expressed genes were involved in photosynthesis. These results enhance
our understanding of the variations that occur in mulberry autotetraploids and will benefit
future breeding work.