Mutual exclusion of anthocyanins and betalains in plant pigmentation
For over 50 years, researchers have investigated the red, yellow, and blue pigments of plants in the Caryophyllales. Only plants in this order can have betalains, while most other land plants are pigmented by anthocyanins. However, the betalain-pigmented Caryophyllales plants do not accumulate anthocyanins. Recent studies by Fan et al., 2020 (now retracted) and Zhou et al., 2020 claimed that anthocyanins would contribute to the pigmentation of red pitayas. We previously addressed issues in the Fan et al., 2020 paper in our response (Pucker et al., 2022). Now, the paper by Zhou et al., 2020 was addressed by two correspondence articles just published in BMC Genomics. Both refute the contribution of anthocyanins to pigmentation in pitaya:
Pucker, B., Brockington, S.F. The evidence for anthocyanins in the betalain-pigmented genus Hylocereus is weak. BMC Genomics 23, 739 (2022). https://doi.org/10.1186/s12864-022-08947-1
Khan, M.I. The reported colour formation mechanism in pitaya fruit through co-accumulation of anthocyanins and betalains is inconsistent and fails to establish the co-accumulation. BMC Genomics 23, 740 (2022). https://doi.org/10.1186/s12864-022-08957-z
If you are interested in this topic, please have a look at these recent publications: Timoneda et al., 2019, Sheehan et al., 2020, and Pucker et al., 2022.