How Genetic Differences Affect Potato Starch and Toxin Levels

Jenn Hoskins
14th March, 2024

How Genetic Differences Affect Potato Starch and Toxin Levels

Image Source: Natural Science News, 2024

Key Findings

  • Study at Wageningen University found 119 potato genes linked to starch production and toxin levels
  • Most harmful mutations in these genes exist but are balanced by normal gene copies
  • About 70% of these genes are active, affecting potato traits like nutrition and safety
Potatoes, a staple food for millions around the world, are not just a source of energy but also a subject of scientific intrigue. Researchers at Wageningen University & Research have taken a closer look at the genetic blueprint that dictates two critical aspects of potatoes: the production of starch and steroidal glycoalkaloids (SGAs), which are natural compounds found in potatoes, some of which can be toxic at high levels[1]. This new research could help improve potato breeding programs by providing insights into how genetic diversity within these pathways influences the potato's nutritional and safety profile. Starch is the primary form of energy storage in potatoes, and its composition is crucial for both the agricultural industry and human nutrition. SGAs, on the other hand, play a defensive role in the plant but can pose a health risk when present in high concentrations in the edible tubers. Understanding the genetic underpinnings of these two pathways is therefore paramount for developing better potato varieties. The study identified 119 genes involved in starch metabolism and SGA biosynthesis, revealing a staggering 96,166 allelic variants among 2,169 gene haplotypes in six autotetraploid potato genomes. Autotetraploid means that the potato has four sets of chromosomes, making its genetic landscape particularly complex. The researchers found that these allelic variants were not evenly distributed, suggesting certain genes may be more critical than others in these pathways. One of the key findings is that most deleterious mutations within these genes are retained in a heterozygous state. This means that although the harmful mutations are present, they are typically paired with a normal copy of the gene, which can mask their negative effects. This is a significant insight because it highlights the resilience of autotetraploid potatoes to maintain function despite genetic mutations. The study also leveraged full-length cDNA sequencing data to show that about 70% of the gene haplotypes for these 119 genes are transcribable, meaning they are actively used to create proteins. This is important because it indicates that a large portion of the genetic variation can potentially influence the potato's traits. Population genetic analyses further identified starch and SGA biosynthetic genes that may be conserved or diverged between potato varieties with different starch or SGA content. This could help breeders select for specific traits with more precision. Previous research has laid the groundwork for this study. For example, the importance of starch phosphorylase (Pho) in starch synthesis and the existence of null mutants with altered starch granules were previously identified[2]. Additionally, the genetic diversity of wild and cultivated potatoes has been explored, highlighting the complexity of potato evolution and the expansion of disease-resistance genes[3]. The current study builds upon these findings by examining the allelic diversity in genes directly related to starch and SGA production. Moreover, the phased genome assemblies of six potato cultivars have revealed the extensive allelic diversity that contributes to the complex transcriptome and predicted proteome of the potato[4]. This diversity is also reflected in the current study's identification of numerous allelic variants in starch and SGA biosynthetic genes. The genetic improvement of starch properties, such as phosphate content, has been previously targeted through genome-wide association studies[5]. The current research adds another layer to this by providing a comprehensive map of genetic variation in starch-related genes, which could be used to further refine breeding strategies. In conclusion, the findings from Wageningen University & Research offer a deeper understanding of the genetic diversity within key metabolic pathways in potatoes. This knowledge is a significant step toward precision breeding, where the goal is to create potato varieties with optimal starch quality and safe levels of SGAs. Such advancements not only benefit the agriculture industry but also have the potential to improve the nutritional value and safety of one of the world's most important food crops.

GeneticsPlant ScienceAgriculture

References

Main Study

1) Allelic variation in the autotetraploid potato: genes involved in starch and steroidal glycoalkaloid metabolism as a case study.

Published 12th March, 2024

Journal: BMC genomics

Issue: Vol 25, Issue 1, Mar 2024

Related Studies

2) Pho1a (plastid starch phosphorylase) is duplicated and essential for normal starch granule phenotype in tubers of Solanum tuberosum L.

https://doi.org/10.3389/fpls.2023.1220973

3) Genome evolution and diversity of wild and cultivated potatoes.

https://doi.org/10.1038/s41586-022-04822-x

4) Phased, chromosome-scale genome assemblies of tetraploid potato reveal a complex genome, transcriptome, and predicted proteome landscape underpinning genetic diversity.

https://doi.org/10.1016/j.molp.2022.01.003

5) Starch phosphorylation associated SNPs found by genome-wide association studies in the potato (Solanum tuberosum L.).

https://doi.org/10.1186/s12863-019-0729-9


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