Genomic insights into Rhizobium anhuiense IY2 isolated from Trifolium caudatum root nodules

Nitrogen fixing Rhizobia play an important role in legume growth and sustainable agriculture, and genome based analyses have become essential for understanding the genetic basis of their symbiotic traits and functional potential. Here, Rhizobium anhuiense strain IY2 was isolated from the root nodules of the endemic legume Trifolium caudatum and characterized using 16 S rRNA and whole-genome sequencing. The genome, sequenced via the Illumina NovaSeq 6000 platform, spans 6,917,460 bp with approximately 6,900 predicted coding sequences (CDSs). Genomic analysis suggested the presence of various genetic determinants potentially linked to plant growth promotion, including those involved in iron acquisition, nitrogen metabolism, stress response, and auxin biosynthesis. While no CRISPR arrays were detected, two prophage regions were identified. Bioinformatic screening via the CARD database identified 47 AMR-related sequences, primarily comprising putative efflux systems and antibiotic targets rather than confirmed resistance determinants. The genome also harbors nod, nif, and fix gene clusters, indicating the genomic potential for symbiotic nitrogen fixation (SNF). Phylogenetic analysis of the nodC amino acid sequence supports a host-specific symbiotic relationship with Trifolium species. Notably, the presence of two distinct copies of the nodD gene suggests a potential for broad host range and strong symbiotic adaptability. This study provides the first genomic insights into the symbiotic association between a rhizobial species and T. caudatum, a legume endemic to Turkey.