Nodulating <i>Aeschynomene indica</i> without Nod Factor Synthesis Genes: In Silico Analysis of Evolutionary Relationship
Mengguang Zhao,
Jingyi Dong,
Zhenpeng Zhang,
Entao Wang,
Dandan Wang,
Huijie Xie,
Chao Wang,
Zhihong Xie
Affiliations
Mengguang Zhao
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Jingyi Dong
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Zhenpeng Zhang
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
Entao Wang
Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11350, Mexico
Dandan Wang
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Huijie Xie
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Chao Wang
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Zhihong Xie
National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shandong Engineering Research Center of Plant-Microbia Restoration for Saline-Alkali Land, College of Resources and Environment, Shandong Agricultural University, Taian 271000, China
Aeschynomene indica rhizobia (AIRs) are special classes of bacteria capable of nodulating without nodulation factors and have photosynthetic capacity. With an aim to characterize the structural variations in Bradyrhizobium genomes during its evolution, the genomes of AIRs and the reference Bradyrhizobium strains were compared utilizing molecular biology, bioinformatics, and biochemistry techniques. The presence of symbiotic nitrogen fixation (nif) genes and photosynthetic genes, as well as components of the T3SS (Type III secretion system) and T3CP (Type III chaperone) in the genome of AIRs, was also assessed. Additionally, the origin, evolutionary history, and genes associated with the NF-independent nodulation pattern in AIRs were explored. The results indicate that horizontal gene transfer events have occurred in AIRs, and three distinct origins of AIRs were estimated: early differentiated AIRs, non-symbiotic Bradyrhizobium, and non-AIRs. In contrast to the significant genetic transformations observed in the second and third groups, the first group of AIRs displays a rich evolutionary history, exhibits high species diversity, and primarily relies on vertical transmission of nitrogen fixation and photosynthetic genes. Overall, the findings provide a fundamental theoretical foundation for gaining a deeper understanding of the phylogeny and genealogy of AIRs.
