A Genetic Variation Influences Redness of Apple Flesh

Jenn Hoskins
15th June, 2024

A Genetic Variation Influences Redness of Apple Flesh

The transcription factor MdWRKY10 physically interacts with the protein MdTTG1 (a–d), an interaction that significantly enhances its ability to activate the key anthocyanin regulator MdMYB10 and increase pigment production in apple cells (e–n).

Image adapted from: Wang et al. / CC BY (Source)

Key Findings

  • The study by Shandong Agricultural University identified MdWRKY10 as a key regulator of red flesh color in apples
  • MdWRKY10 binds to the promoter of MdMYB10, enhancing its transcription and boosting anthocyanin synthesis
  • This discovery provides new targets for breeding apples with better color and nutritional value
Understanding the genetic mechanisms behind fruit coloration can lead to significant advancements in crop improvement and nutritional value. A recent study conducted by Shandong Agricultural University has identified a novel regulatory role of the WRKY-containing protein complex in the formation of red flesh apple phenotypes, providing broader insights into the molecular mechanism governing anthocyanin synthesis in plants[1]. Anthocyanins are pigments responsible for the red, purple, and blue colors in many fruits and vegetables. They are known for their health benefits, including protection against a range of human diseases[2]. In apple (Malus domestica), the MYB10 transcription factor is known to confer a red-flesh phenotype due to a minisatellite insertion in its R6 promoter. However, the degree of red pigmentation varies, suggesting the involvement of additional genetic factors. The study by Shandong Agricultural University has uncovered that MdWRKY10, a transcription factor, binds to the promoter of MdMYB10 and activates its transcription. This interaction is crucial for enhancing anthocyanin synthesis in apple flesh. MdWRKY10 specifically interacts with the WDR protein MdTTG1 to form the apple MYB-bHLH-WDR (MBW) complex, significantly boosting its transcriptional activation activity. The researchers identified a 163-bp InDel in the promoter region of MdWRKY10 alleles, which contains a typical W-box element that MdWRKY10 binds to for transactivation. This binding leads to increased transcript levels of both MdWRKY10 and MdMYB10, resulting in enhanced anthocyanin synthesis and varying degrees of red pigmentation in apple flesh. This discovery builds on previous research that has highlighted the importance of transcription factors in regulating fruit color. For instance, in tomato, the MYB12 transcription factor was found to play a significant role in regulating the flavonoid pathway, affecting fruit color by controlling the accumulation of naringenin chalcone, a yellow-colored flavonoid[3]. Similarly, the current study shows that the interaction between MdWRKY10 and MdMYB10 is essential for anthocyanin synthesis in apples, thus influencing the red flesh phenotype. The findings also align with broader trends in fruit crop research, where understanding the genetic and molecular bases of traits can lead to improved crop varieties. For example, the study of flavonoid accumulation in apples has shown that genetic diversity and the use of wild germplasm resources, such as Malus sieversii, are critical for breeding high-flavonoid apple varieties[4]. The current study's identification of MdWRKY10's role in anthocyanin synthesis provides a new target for breeding apples with enhanced nutritional qualities. Moreover, the study's implications extend to other fleshy-fruited species, as the regulatory networks governing fruit development and maturation are often conserved across different species[5]. This conservation suggests that similar genetic mechanisms could be manipulated in other crops to improve their color and nutritional value. In summary, the research conducted by Shandong Agricultural University has identified MdWRKY10 as a key player in the regulation of anthocyanin synthesis in apples, working in conjunction with MdMYB10. This discovery not only advances our understanding of the genetic factors influencing fruit color but also opens new avenues for breeding nutritionally superior fruit varieties. By leveraging these insights, researchers and breeders can develop crops that are not only more visually appealing but also offer greater health benefits.

FruitsGeneticsPlant Science

References

Main Study

1) A Functional InDel in the WRKY10 Promoter Controls the Degree of Flesh Red Pigmentation in Apple.

Published 14th June, 2024

https://doi.org/10.1002/advs.202400998

Related Studies

2) Enrichment of tomato fruit with health-promoting anthocyanins by expression of select transcription factors.

https://doi.org/10.1038/nbt.1506

3) Biochemical and molecular analysis of pink tomatoes: deregulated expression of the gene encoding transcription factor SlMYB12 leads to pink tomato fruit color.

https://doi.org/10.1104/pp.109.147322

4) Malus sieversii: the origin, flavonoid synthesis mechanism, and breeding of red-skinned and red-fleshed apples.

https://doi.org/10.1038/s41438-018-0084-4


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