Expression studies on AUX1-like genes in Medicago truncatula suggest that auxin is required at two steps in early nodule development

• Published in: Molecular plant-microbe interactions Vol. 14; no. 3; pp. 267 - 277
• Main Authors: de Billy, F, Grosjean, C, May, S, Bennett, M, Cullimore, J V
• Format: Journal Article
• Language: English
• Published: United States The American Phytopathological Society 01.03.2001
• Subjects: Amino Acid Sequence; Arabidopsis Proteins; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Differentiation; Gene Expression Regulation, Plant; In Situ Hybridization; Indoleacetic Acids - metabolism; legume-rhizobium symbiosis; Medicago sativa - genetics; Medicago sativa - growth & development; Medicago sativa - microbiology; Molecular Sequence Data; organogenesis; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - microbiology; Reverse Transcriptase Polymerase Chain Reaction; Sequence Alignment; signaling; Sinorhizobium meliloti; Symbiosis
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.2001.14.3.267

Medicago truncatula contains a family of at least five genes related to AUX1 of Arabidopsis thaliana (termed MtLAX genes for Medicago truncatula-like AUX1 genes). The high sequence similarity between the encoded proteins and AUX1 implies that the MtLAX genes encode auxin import carriers. The MtLAX genes are expressed in roots and other organs, suggesting that they play pleiotropic roles related to auxin uptake. In primary roots, the MtLAX genes are expressed preferentially in the root tips, particularly in the provascular bundles and root caps. During lateral root and nodule development, the genes are expressed in the primordia, particularly in cells that were probably derived from the pericycle. At slightly later stages, the genes are expressed in the regions of the developing organs where the vasculature arises (central position for lateral roots and peripheral region for nodules). These results are consistent with MtLAX being involved in local auxin transport and suggest that auxin is required at two common stages of lateral root and nodule development: development of the primordia and differentiation of the vasculature.