Grass Rhizome Proteomics Reveals Convergent Freezing-Tolerance Strategies

Oren, E.; Zhai, J.; Rooney, T. E.; Angelovici, R.; Hale, C. O.; Brindisi, L. J.; Hsu, S.-K.; Gault, C. M.; Hua, J.; La, T.; Lepak, N.; Fu, Q.; Buckler, E. S.; Romay, M. C.

doi:10.1101/2025.05.15.654294

bioRxiv · 10.1101/2025.05.15.654294

Grass Rhizome Proteomics Reveals Convergent Freezing-Tolerance Strategies

Oren, E.·Zhai, J.·Rooney, T. E.·Angelovici, R.·Hale, C. O.·Brindisi, L. J.·Hsu, S.-K.·Gault, C. M.·Hua, J.·La, T.·Lepak, N.·Fu, Q.·Buckler, E. S.·Romay, M. C.

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Abstract

O_LIGrasses in the PACMAD clade independently colonized cold environments from warm-climate ancestors, but whether their molecular responses to freezing reflect shared evolutionary solutions or lineage-specific innovations remains unknown. We used comparative proteomics to test whether protein-level cold responses show stronger cross-species conservation than previously observed at the transcript level. C_LIO_LIWe quantified seasonal rhizome proteomes (winter vs summer) from five PACMAD species grown in a common garden exposed to sustained sub-zero temperatures, identified differentially abundant proteins, and compared fold-change magnitudes across species using orthogroup-based correlation analyses. We further examined LEA3 protein structure through hydropathy profiling and motif analysis. C_LIO_LIShared cold-responsive proteins showed higher cross-species fold-change correlation ({rho} = 0.80) than background proteins ({rho} = 0.45), despite greater divergence in baseline abundance. LEA3 was the only ortholog elevated across all five species. Cold-tolerant species contained more tandem 11-mer repeats than the cold-sensitive maize, and two species accumulated multiple LEA3 paralogs, increasing total LEA3 abundance. C_LIO_LIIndependent evolution of freezing tolerance in PACMAD grasses is governed by evolutionary constraints on protein-level response magnitude, reflecting the retention of an ancestral protective capacity. Structural divergence of LEA3 in maize suggests that transcriptional induction alone does not ensure freezing tolerance; functional protection likely requires intact motif architecture. C_LI

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Oren, E., Zhai, J., Rooney, T. E., Angelovici, R., Hale, C. O., Brindisi, L. J., Hsu, S.-K., Gault, C. M., Hua, J., La, T., Lepak, N., Fu, Q., Buckler, E. S., Romay, M. C.. 2025-05-19. Grass Rhizome Proteomics Reveals Convergent Freezing-Tolerance Strategies. https://doi.org/10.1101/2025.05.15.654294

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