Sweet potato (Ipomoea batatas), a globally significant staple crop, exhibits remarkable adaptability to various environmental conditions, largely due to its genetic diversity. Recent studies have revealed the presence of naturally integrated Agrobacterium cellular T-DNAs (cT-DNAs) within the sweet potato genome, suggesting their possible role in the evolution and adaptation of sweet potato. In this study, we characterize a newly identified open reading frame (ORF) within the cT-DNA2 region of I. batatas, which encodes a homolog of the A. rhizogenes rolD gene. This ORF encodes a RolD-like protein with ornithine cyclodeaminase (OCD) activity, a key enzyme in proline biosynthesis. Functional assays confirmed that the recombinant RolD-like protein exhibits ornithine-dependent NAD