Researchers have identified the genetic mechanisms that determine whether a potato develops a smooth or russet skin texture. By comparing the smooth-skinned Z43 variety with the russet Innovator cultivar, scientists pinpointed a specific locus on chromosome 4 that acts as a primary control switch for this trait.
The study, led by the Chinese Academy of Agricultural Sciences, focused on the StPXG4 gene. This gene encodes a peroxygenase that appears to influence how the potato periderm renews itself. In smooth-skinned potatoes, the outer layers shed cleanly. In russet varieties, these layers crack and remain attached, resulting in a rough surface. The research team found that suberin levels are higher in smooth skins, while lignin accumulation is more prevalent in the rougher, russet textures.
Genetic analysis showed that skin texture is a highly heritable trait, with a 93.1% broad-sense heritability rate. By developing four specific insertion/deletion markers, the researchers have provided a new tool for breeders. These markers allow for the selection of desired skin traits early in the growth cycle, long before the tubers reach maturity. This shift toward marker-assisted selection could reduce the time required to develop new potato varieties that balance visual appearance with durability.
While the StPXG4 gene is a strong candidate, the team notes that further functional testing is necessary to confirm exactly how it regulates periderm development. The findings provide a clear framework for understanding the interaction between cell wall formation and gene expression. As breeders test these markers across different environments, they may find more effective ways to manage post-harvest bruising and water loss in commercial potato crops.