Gene Discovery Shows How a Protein Controls Green Skin in Squash

Jenn Hoskins
12th August, 2024

Gene Discovery Shows How a Protein Controls Green Skin in Squash

Image Source: Natural Science News, 2024

Key Findings

  • The study by the Chinese Academy of Agricultural Sciences focused on the genetic basis of green and white fruit peel colors in Cucurbita pepo
  • Researchers found that white peel color is dominant over green, controlled by a single recessive gene (Cpgp)
  • The gene responsible for green peel color, Cp4.1LG05g02070, was identified on chromosome 5 and is linked to chlorophyll content differences during fruit development
Fruit peel color is a significant factor influencing fruit quality and consumer preferences. Despite its importance, the molecular mechanisms underlying the green fruit peel color trait in Cucurbita pepo L. have remained elusive. A recent study conducted by the Chinese Academy of Agricultural Sciences aimed to uncover these mechanisms by investigating two parental lines of C. pepo, RP16 and RP38, which exhibit white and green peel colors, respectively[1]. The study utilized 384 F2 populations derived from a cross between RP16 and RP38 to understand the inheritance pattern associated with the green and white fruit peel traits in C. pepo. The findings revealed a 3:1 ratio of white to green peels among the F2 individuals, indicating that the white peel color is dominant over the green peel color, and a single recessive gene (Cpgp) controls the green fruit peel trait. Chlorophyll content analysis showed that in the RP16 line, chlorophyll levels decreased as the fruit matured. Conversely, in the RP38 line, chlorophyll content increased during fruit development, suggesting a genetic basis for the difference in peel color. To identify the specific genetic locus responsible for the green peel color, the researchers conducted a Bulked Segregant Analysis (BSA) followed by sequencing. This analysis pinpointed the Cpgp locus on chromosome 5 within a 2.3 Mb region. Further fine-mapping using 699 F2 plants narrowed this region down to 23.90 kb. Within this narrowed region, two annotated genes, Cp4.1LG05g02070 and Cp4.1LG05g02060, were identified. These genes are predicted to encode a two-component Arabidopsis Pseudo-Response Regulator 2-like protein (APRR2), which is known to be involved in pigmentation processes in plants. Sequence alignment and gene expression analyses at various stages of fruit development indicated that Cp4.1LG05g02070 is likely the primary candidate gene responsible for regulating the green fruit peel color trait in C. pepo. This study builds on previous research on plant pigmentation and genetic traits. For instance, a similar approach was used to identify the gene responsible for the green rind color in eggplant, where a single dominant gene was found to control the trait. The gene, EGP19168.1, was fine-mapped to a 20.36 Kb interval on chromosome 8, and a SNP deletion led to a premature termination codon in white-skinned eggplant[2]. The current study on C. pepo employs comparable genetic mapping techniques to achieve its findings. Additionally, the role of APRR2-like proteins in pigmentation is supported by previous studies, such as the one on eggplant, where the Arabidopsis pseudo-response regulator2 (APRR2) was implicated in controlling rind color[2]. This consistency across studies highlights the importance of APRR2-like proteins in plant pigmentation and offers a potential target for genetic manipulation in crop breeding programs. The findings from the Chinese Academy of Agricultural Sciences provide a foundation for further research into the basic mechanisms controlling fruit peel colors in Cucurbita spp. Understanding these genetic mechanisms can aid in the development of new varieties with desirable traits, such as improved fruit quality and increased consumer appeal. This study also complements previous research on other crops, such as pumpkin and cucumber, where genetic loci responsible for traits like vine length and fruit quality have been identified[3][4]. In conclusion, the identification of Cp4.1LG05g02070 as a candidate gene for the green peel color trait in C. pepo not only advances our understanding of plant pigmentation but also opens up new avenues for crop improvement. By leveraging these genetic insights, breeders can develop new varieties that meet market demands and enhance agricultural productivity.

FruitsGeneticsPlant Science

References

Main Study

1) Map-based cloning reveals Cpgp gene encoding an APRR2 protein to regulate the green fruit peel formation in Cucurbita pepo.

Published 12th August, 2024

https://doi.org/10.1007/s11032-024-01492-7

Related Studies

2) Fine Mapping and Identification of SmAPRR2 Regulating Rind Color in Eggplant (Solanum melongena L.).

https://doi.org/10.3390/ijms24043059

3) Fine mapping identified the gibberellin 2-oxidase gene CpDw leading to a dwarf phenotype in squash (Cucurbita pepo L.).

https://doi.org/10.1016/j.plantsci.2021.110857

4) Molecular research progress and improvement approach of fruit quality traits in cucumber.

https://doi.org/10.1007/s00122-021-03895-y


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