title: Function of Cyclophilin1 as a long-distance signal molecule in the phloem of tomato plants.
abstract: Tomato (Solanum lycopersicum) diageotropica (dgt) mutants, containing a single mutation in the Cyclophilin1 (SlCyp1) gene, are auxin-insensitive, exhibiting a pleiotropic phenotype including lack of geotropism, abnormal xylem structure, lack of lateral roots (LRs), and elevated shoot-to-root ratio. SlCyp1 is a putative peptidyl-prolyl isomerase that can traffic from shoot to root, where it induces changes in auxin response, LR formation, and xylem development, suggesting it has a role as a long-distance signaling molecule. Here, we explored the mechanism underlying SlCyp1 function in the phloem. Expression of SlCyp1 under a phloem-specific (AtSuc2) promoter in dgt plants partially restored the wild-type phenotype, including lateral root development, root branching, and xylem morphology. The observed developmental changes were associated with physiological alternations at the whole-plant level, including a reduction in shoot-to-root ratio, enhanced transpiration, and elevated photosynthetic rates. Conversely, phloem-specific expression of SlCyp1 active-site mutants did not restore the wild-type phenotype. Local inhibition of cyclophilin functioning in the target tissue reduced auxin sensitivity, suggesting that its enzymatic activity in the distant organ is required for its action as a long-distance signalling agent. The data presented suggest that SlCyp1 is a signal molecule trafficking from shoot to root where its activity is required for auxin-mediated lateral root development.
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Spiegelman
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel.
authors.forename: Sumita
authors.initials: S
authors.lastname: Omer
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel.
authors.forename: Ben N
authors.initials: BN
authors.lastname: Mansfeld
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, Rehovot 76100, Israel.
authors.forename: Shmuel
authors.initials: S
authors.lastname: Wolf
mesh_terms: D021983:Cyclophilins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000502:physiology*; D052585:Phloem / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D021983:Cyclophilins
keywords: Auxin; Solanum lycopersicum.; cyclophilin; diageotropica; phloem; root development