title: Identification and Analysis of Medicago truncatula Auxin Transporter Gene Families Uncover their Roles in Responses to Sinorhizobium meliloti Infection.
abstract: Auxin transport plays a pivotal role in the interaction between legume species and nitrogen-fixing bacteria to form symbioses. Auxin influx carriers auxin resistant 1/like aux 1 (AUX/LAX), efflux carriers pin-formed (PIN) and efflux/conditional P-glycoprotein (PGP/ABCB) are three major protein families participating in auxin polar transport. We used the latest Medicago truncatula genome sequence to characterize and analyze the M. truncatula LAX (MtLAX), M. truncatula PIN (MtPIN) and M. truncatula ABCB (MtABCB) families. Transient expression experiments indicated that three representative auxin transporters (MtLAX3, MtPIN7 and MtABCB1) showed cell plasma membrane localizations. The expression of most MtLAX, MtPIN and MtABCB genes was up-regulated in the roots and was down-regulated in the shoots by Sinorhizobium meliloti infection in the wild type (WT). However, the expression of these genes was down-regulated in both the roots and shoots of an infection-resistant mutant, dmi3. The different expression patterns between the WT and the mutant roots indicated that auxin relocation may be involved in rhizobial infection responses. Furthermore, IAA contents were significantly up-regulated in the shoots and down-regulated in the roots after Sinorhizobium meliloti infection in the WT. Inoculation of roots with rhizobia may reduce the auxin loading from shoots to roots by inhibiting the expression of most auxin transporter genes. However, the rate of change of gene expression and IAA contents in the dmi3 mutant were obviously lower than in the WT. The identification and expression analysis of auxin transporter genes helps us to understand the roles of auxin in the regulation of nodule formation in M. truncatula.
authors.affiliation: College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China These authors contributed equally to this work. shencj@hznu.edu.cn whz62@163.com.
authors.forename: Chenjia
authors.initials: C
authors.lastname: Shen
authors.affiliation: Henan Academy of Agricultural Sciences, Zhengzhou 450002, China These authors contributed equally to this work.
authors.forename: Runqing
authors.initials: R
authors.lastname: Yue
authors.affiliation: Key Laboratory of Tea Plant Biology and Resources Utilization, Ministry of Agriculture, Tea Research Institute of the Chinese Academy of Agricultural Sciences (TTICAAS), Hangzhou 310008, China These authors contributed equally to this work.
authors.forename: Youhuang
authors.initials: Y
authors.lastname: Bai
authors.affiliation: The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agriculture and Food Science, Zhejiang A & F University, Lin'an 311300, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Feng
authors.affiliation: College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.affiliation: The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agriculture and Food Science, Zhejiang A & F University, Lin'an 311300, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
authors.forename: Shuanggui
authors.initials: S
authors.lastname: Tie
authors.affiliation: College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China shencj@hznu.edu.cn whz62@163.com.
authors.forename: Huizhong
authors.initials: H
authors.lastname: Wang
mesh_terms: D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D046913:Medicago truncatula / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins
keywords: Auxin; Auxin transport; Medicago truncatula; Sinorhizobium meliloti infection; Symbiosis; dmi3