How a Specific Protein Controls the Pink Color in Watermelons

Greg Howard
11th May, 2024

How a Specific Protein Controls the Pink Color in Watermelons

Image Source: Natural Science News, 2024

Key Findings

  • Scientists discovered a gene, Clpf, that gives watermelons their pink flesh color
  • The gene ClPPR5 affects the amount of carotenoids, which are important for human health
  • This knowledge could lead to breeding watermelons with higher nutritional value
Watermelons are not just a refreshing summer snack; they are also a treasure trove of nutrients, particularly carotenoids, which are responsible for their vibrant flesh colors. Carotenoids are pigments that play a crucial role in plant coloration and human health, but our bodies cannot produce them. Instead, we must obtain them through our diet, where fruits and vegetables like watermelons come into play[2]. Researchers from Northeast Agricultural University have made a breakthrough in understanding how watermelons develop their distinctive pink flesh[1]. This discovery is not only fascinating for geneticists but also holds promise for enhancing the nutritional value of this popular fruit. The study focused on identifying the genetic basis for the pink flesh color of certain watermelon varieties. Through meticulous breeding and mapping techniques, scientists pinpointed a specific gene, dubbed Clpf, which is responsible for the pink flesh trait. The gene was located within a 55.26-kilobase region on chromosome 6, and the prime candidate for this gene was identified as Cla97C06G122120, also known as ClPPR5, which belongs to the pentatricopeptide repeat (PPR) protein family. PPR proteins are known to be involved in gene expression within organelles such as chloroplasts[3]. The study's findings suggest that this particular PPR protein, ClPPR5, may regulate the accumulation of carotenoids in watermelon flesh. This is especially intriguing as it links the PPR protein's role in plant development and pigment accumulation, expanding our knowledge of PPR protein functions beyond what has previously been established in other plants like Arabidopsis[3]. To understand the influence of ClPPR5 on pigment accumulation, the researchers compared the flesh of two watermelon lines: one with red flesh and the other with pink flesh. They found that the pink flesh watermelons had lower lycopene content, which is a key carotenoid responsible for the red color in fruits[4]. Furthermore, the pink-fleshed watermelons also had fewer and smaller chromoplasts, which are the organelles where carotenoids are stored. The study went a step further by silencing a homologous gene in tomatoes, which are closely related to watermelons and also accumulate high levels of carotenoids during ripening[4]. The tomatoes with the silenced gene showed a reduction in carotenoid content, supporting the idea that the PPR gene plays a role in regulating pigment production. This research not only provides a deeper understanding of the genetic mechanisms that determine watermelon flesh color but also has practical implications. With this knowledge, breeders can develop new varieties with enhanced levels of carotenoids, potentially increasing the nutritional value of watermelons. As carotenoids have been associated with various health benefits, including improved eye health and reduced risk of chronic diseases, the ability to boost their levels in watermelons could have significant implications for public health[2]. The findings from Northeast Agricultural University's study are a step toward a future where the watermelons we enjoy on hot summer days could be even more beneficial to our health. By leveraging the power of genetics, the vibrant colors of watermelon flesh could translate into a richer source of essential nutrients.

FruitsGeneticsPlant Science

References

Main Study

1) Clpf encodes pentatricopeptide repeat protein (PPR5) and regulates pink flesh color in watermelon (Citrullus lanatus L.).

Published 10th May, 2024

https://doi.org/10.1007/s00122-024-04619-8

Related Studies

2) Carotenoids in human nutrition and health.

https://doi.org/10.1016/j.abb.2018.06.001

3) Arabidopsis emb175 and other ppr knockout mutants reveal essential roles for pentatricopeptide repeat (PPR) proteins in plant embryogenesis.

Journal: Planta, Issue: Vol 221, Issue 3, Jun 2005

4) Changes in color-related compounds in tomato fruit exocarp and mesocarp during ripening using HPLC-APcI(+)-mass Spectrometry.

https://doi.org/10.1007/s13197-012-0782-0


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