Establishment Of Stable Genetic Transformation System Of Medicago Truncatula And Indentification Of Transformed Plants Harboring MtROP5

Medicago truncatula is a model legume plant and an ideal research material for studying legume and rhizobia symbiotic interaction. Stable and highly efficient genetic transformation method is a significant tool for reverse genetics research. M. truncatula genetic transformation is relatively difficult, which restricts the research on symbiotic interaction between legume plants and rhizobia.So establishment of stable and highly efficient genetic transformation of M. truncatula can provide technique platform for studying the mechanism of symbiotic interaction between M. truncatula and rhizobia.ROP GTPases are a type of small G proteins, acting as molecular switches which function in many aspects of plant cell development, including vesicle transportation, signal transduction, and cell polarized growth. Our prevous work showed that MtROP5may participate in regulation of symbiotic interaction. In order to further study the role of MtROP5in symbiosis, we transformed ROP5-OX (overexpression), ROP5-RNAi (RNA interference), ROP5-CA (constitutively active), ROP5-DN (dominant negative), and ROP5promoter with GUS fusion into M. truncatula. Leaves of M. truncatula ecotype R108-1were selected as the explants. Through optimizing the selection of explants, infection time, co-culture time, bacterial concentration, pump infiltration time, we establised a stable and high effective transformation system of M. truncatula. By GUS staining and PCR amplification, we found that the positive rate of transformed plants reach to80%.We focused on studying expression pattern of MtROP5promoter. GUS staining showed that MtROP5is expressed in roots, stems, flowers, pods, and seeds, and predominatly expressed in vascular tissues of roots. This work provides materials and foundation for deeply studying the roles of ROP5in symbiosis.