Flower symmetry
Flowers come in different forms and shapes, but they all have symmetry. Chinese researchers show in Science Advances how plants regulate that symmetry.
Flowers show different forms of symmetry. There are flowers of which each petal is identical to its neighbour, these flowers are multiple symmetrical. But you have also flowers that only show a left-right symmetry, like those of the monkeyflowers (Mimulus). Those flowers consist of two large petals at the top, two smaller petals at the bottom, and a nectar spur containing petal in the middle at the bottom. The researchers decided to figure out the regulation behind those two-sided symmetry flowers.
Firstly they created mutants. In this case mutants that instead of two-sided symmetry showed multiple symmetry. In these flowers, it turned out that a protein for turning on and off other genes, the flower symmetry gen CYCLOIDEA, to be more abundant. More CYCLOIDEA appears to cause the multiple symmetry.
A feedback loop between CYCLOIDEA and BLADE-ON-PETIOLE enables the two-sided symmetry
Subsequently the researchers analysed which gene in the mutants was altered, they found the mutation back in the gene BLADE-ON-PETIOLE. Now the researchers could figure out how the flower symmetry is regulated by BLADE-ON-PETIOLE. First they found out through fishing which proteins bind to BLADE-ON-PETIOLE. This appeared to be both CYCLOIDEA and a protein that marks proteins for degradation. But they did not bind simultaneously.
Binds CYCLOIDEA to BLADE-ON-PETIOLE, then BLADE-ON-PETIOLE is not broken down, but instead it puts a break on the production of CYCLOIDEA. This in turn causes more breakdown of BLADE-ON-PETIOLE. This feedback loop ensures that CYCLOIDEA is only produced in the upper two petals. Interferes a mutation the feedback loop, then all petals get the message from CYCLOIDEA to develop themselves into large petals.
Literature
Yuan Gao et al., BLADE-ON-PETIOLE interacts with CYCLOIDEA to fine-tune CYCLOIDEA-mediated flower symmetry in monkeyflowers (Mimulus).Sci. Adv.10 ,eado4571(2024). DOI: 10.1126/sciadv.ado4571
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