Purpose This study aimed to clarify the evolutionary patterns and structural divergence characteristics of the major intrinsic protein (MIP) gene family in cultivated and wild Oryza species.
Methods Based on multi-species genomic data, the MIP gene family was identified and analyzed through phylogenetic analysis, comparison of key regions, gene family expansion and contraction analysis, selection pressure evaluation, and structural clustering.
Results A total of 2113 MIP homologous proteins were identified from 59 Oryza accessions. These proteins were generally classified into four classical subfamilies, namely PIP, TIP, NIP, and SIP, indicating a relatively stable classification pattern of the MIP family in Oryza. A small number of MIP-related orthogroups showed local copy number variation in several wild rice accessions. The two NPA motifs and their associated key regions were generally conserved, although local amino acid differences were observed at several sites. Structural analysis showed that most MIP proteins retained a typical aquaporin fold, while local structural divergence was also observed.
Conclusion The Oryza MIP family is generally conserved, but local sequence and structural differentiation exists among different members. Wild rice contains noteworthy variation resources related to MIP family diversification. This study provides a reference for the subsequent screening of elite germplasm resources associated with water transport and drought adaptation.
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