Deciphering the Atlas of Protein Acetylation, 2‑Hydroxyisobutyrylation, and Malonylation in Developing Cassava Roots

Lysine acetylation (Kac), 2-hydroxyisobutyrylation (Khib),
and
malonylation (Kma) represent three recently identified posttranslational
modifications (PTMs) that regulate plant development and stress resilience.
Herein, we constructed the first global proteomic atlas of Kac, Khib,
and Kma modifications in developing cassava roots, identifying 11,253
Kac, 18,326 Khib, and 4068 Kma sites across 5165, 4832, and 1815 proteins,
respectively. The PTM-modified proteins were involved in sucrose/starch
metabolism, glycolysis/gluconeogenesis, pentose phosphate pathway,
TCA cycle, and lignin biosynthesis, with the majority exhibiting multiple
PTM co-occurrence. Hundreds of modified proteins associated with stress
response, hormone metabolism, and transcription factors were also
identified, of which a few proteins displayed significant type-specific
modification preferences. Finally, the regulatory roles of Kac-, Khib-,
and Kma-modified proteins in root development and stress responses
were discussed, leading to a proposed mechanistic model for PTM-mediated
regulation in cassava. These findings provide novel insights for elucidating
the molecular mechanisms of PTM-driven regulation in plants.