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bioRxiv · 10.64898/2026.08.04.742752

ABC1K7: A 350-Myr chloroplast rheostat fine-tuned during coconut domestication

You, N.·Chen, Y.·John, M.·Zhou, N.·Li, W.·Cao, H.·Sun, C.
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Abstract

Perennial crops follow different domestication trajectories from annuals, yet the molecular basis of slow-variable domestication--subtle tuning of conserved regulatory hubs--remains poorly characterized. We reconstructed the evolutionary history of the chloroplast kinase ABC1K7 across 9 seed plant species spanning [~]350 Myr, employing PAML codon models, IQ-TREE robust codon models, and protein-level phylogenetic inference, with AlphaFold2 structural modeling. ABC1K7 was under extreme purifying selection ({omega} = 0.073-0.104) across all seed plants. In coconut, a single Y[->]F substitution at residue 652--located >30 [A] from the catalytic core in a predicted intrinsically disordered region--represents the only non-synonymous change differentiating coconut from 7 of 8 angiosperm orthologs, and exhibits perfect co-segregation with domestication traits across a 17-year breeding panel (n = 327). These findings provide population-level evidence consistent with the slow-variable domestication model, identifying ABC1K orthologs as targets for perennial crop improvement.

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You, N., Chen, Y., John, M., Zhou, N., Li, W., Cao, H., Sun, C.. 2026-08-09. ABC1K7: A 350-Myr chloroplast rheostat fine-tuned during coconut domestication. https://doi.org/10.64898/2026.08.04.742752

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