Potato skin is more than a surface feature: it shapes market appeal while helping tubers limit water loss and withstand environmental stress and mechanical damage. A new study has mapped a major genetic region associated with smooth and russet skin and identified the gene StPXG4 as a leading candidate underlying this difference. By linking skin anatomy, cell-wall chemistry, genetic variation and gene expression, the researchers showed that russeting develops as cracked outer layers remain attached and accumulate during tuber growth. The findings provide new biological insight into a commercially important trait and offer molecular resources that may help breeders develop potatoes with more predictable appearance and protective performance.
As potato tubers expand underground, their periderm must renew itself while preserving a protective barrier. In smooth-skinned cultivars, older outer cells are shed, leaving a thin and glossy surface. In russet-skinned cultivars, these layers can remain attached, crack and build up into a thicker, rougher covering. Previous research suggested that skin texture is shaped by several genes as well as temperature, humidity and nutrient conditions, but the main loci and regulatory pathways remained unresolved. Breeders therefore lacked validated markers for selecting this trait early, and the links among tissue organization, suberin, lignin and gene activity were incomplete. Based on these challenges, there is a need to investigate the genetic and molecular basis of potato tuber skin texture in greater depth.
Researchers from the State Key Laboratory of Vegetable Biobreeding; the Key Laboratory of Biology and Genetic Improvement of Tuber and Root Crop of Ministry of Agriculture and Rural Affairs; and the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, published (DOI: 10.1093/hr/uhag102) the study on March 13, 2026, in Horticulture Research . Using a population derived from the smooth-skinned potato ( Solanum tuberosum ) cultivar Zhongshuzao43 (Z43) and the russet-skinned cultivar Innovator, the team identified a quantitative trait locus (QTL) on chromosome 4, highlighted StPXG4 as a candidate gene, and proposed two myeloblastosis (MYB)-family transcription factors as possible upstream regulators.
The researchers evaluated 272 first-generation (F1) progeny in Hebei and Inner Mongolia over two consecutive years. Skin texture showed broad-sense heritability of 93.1%, indicating that genetic effects were strong and consistent across environments. Bulked segregant analysis (BSA), performed with two independent mapping methods, located a major QTL within a 1.94-megabase interval on chromosome 4. Four insertion/deletion (indel) markers were developed to validate the region; their average agreement with skin phenotype exceeded 80%, and three exceeded 90%. Scanning electron microscopy (SEM) and tissue sectioning showed that Z43 maintained compact, orderly skin layers, whereas Innovator developed progressively wider cracks and accumulated additional retained layers as tubers expanded. Chemical analyses found higher suberin accumulation in smooth skin but higher lignin accumulation in russet skin, a pattern also observed in selected progeny. RNA sequencing (RNA-seq) across three developmental stages revealed differentially expressed genes (DEGs) enriched in cell-wall formation and lignin-, fatty-acid- and suberin-related pathways. Integrating these results with the QTL identified the StPXG4 gene, which encodes a peroxygenase, as the strongest candidate. Its expression was consistently higher in smooth-skinned varieties. Co-expression analysis linked StPXG4 with the transcription factors StMYB103 and StMYB58, but these proposed regulatory relationships still require direct functional testing.
The authors said the study connects what breeders see on the tuber surface with the cellular, chemical and genetic processes developing beneath it. They said persistent cracking and retention of older skin layers appear to be central to russet formation, while contrasting suberin and lignin accumulation helps distinguish smooth and rough skins. They also stressed that StPXG4 is a high-priority candidate gene rather than a functionally confirmed causal gene. Further experiments will be needed to determine how it changes periderm development and whether StMYB103 and StMYB58 directly regulate its activity.
The chromosome 4 locus and its linked indel markers could support marker-assisted selection (MAS), enabling breeders to assess skin-texture potential before mature tubers can be evaluated reliably. Such tools may shorten selection cycles and make it easier to balance visual quality with resistance to bruising, water loss and mechanical injury. However, the markers should first be tested across broader breeding populations and production environments. Functional validation of StPXG4 will also be essential before it can be used confidently in precision-breeding strategies. By clarifying how skin layers, suberin, lignin and gene regulation interact, the study establishes a framework for improving potato appearance and protective skin traits without treating smoothness and toughness as a simple either-or choice.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhag102
Funding i nformation
This work was supported by the National Natural Science Foundation of China, grant 32172090; China Agriculture Research System, project CARS-9.
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.
Horticulture Research
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Genetic architecture and major genes for tuber skin texture in potato
13-Mar-2026
The authors declare that they have no competing interests.