title: Vascularization, high-volume solution flow, and localized roles for enzymes of sucrose metabolism during tumorigenesis by Agrobacterium tumefaciens.
abstract: Vascular differentiation and epidermal disruption are associated with establishment of tumors induced by Agrobacterium tumefaciens. Here, we address the relationship of these processes to the redirection of nutrient-bearing water flow and carbohydrate delivery for tumor growth within the castor bean (Ricinus communis) host. Treatment with aminoethoxyvinyl-glycine showed that vascular differentiation and epidermal disruption were central to ethylene-dependent tumor establishment. CO2 release paralleled tumor growth, but water flow increased dramatically during the first 3 weeks. However, tumor water loss contributed little to water flow to host shoots. Tumor water loss was followed by accumulation of the osmoprotectants, sucrose (Suc) and proline, in the tumor periphery, shifting hexose-to-Suc balance in favor of sugar signals for maturation and desiccation tolerance. Concurrent activities and sites of action for enzymes of Suc metabolism changed: Vacuolar invertase predominated during initial import of Suc into the symplastic continuum, corresponding to hexose concentrations in expanding tumors. Later, Suc synthase (SuSy) and cell wall invertase rose in the tumor periphery to modulate both Suc accumulation and descending turgor for import by metabolization. Sites of abscisic acid immunolocalization correlated with both central vacuolar invertase and peripheral cell wall invertase. Vascular roles were indicated by SuSy immunolocalization in xylem parenchyma for inorganic nutrient uptake and in phloem, where resolution allowed SuSy identification in sieve elements and companion cells, which has widespread implications for SuSy function in transport. Together, data indicate key roles for ethylene-dependent vascularization and cuticular disruption in the redirection of water flow and carbohydrate transport for successful tumor establishment.
authors.affiliation: Institute of Botany, Darmstadt University of Technology, Schnittspahnstrasse 3, 64287 Darmstadt, Germany.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Wächter
authors.forename: Markus
authors.initials: M
authors.lastname: Langhans
authors.forename: Roni
authors.initials: R
authors.lastname: Aloni
authors.forename: Simone
authors.initials: S
authors.lastname: Götz
authors.forename: Anke
authors.initials: A
authors.lastname: Weilmünster
authors.forename: Ariane
authors.initials: A
authors.lastname: Koops
authors.forename: Leopoldine
authors.initials: L
authors.lastname: Temguia
authors.forename: Igor
authors.initials: I
authors.lastname: Mistrik
authors.forename: Jan
authors.initials: J
authors.lastname: Pavlovkin
authors.forename: Uwe
authors.initials: U
authors.lastname: Rascher
authors.forename: Katja
authors.initials: K
authors.lastname: Schwalm
authors.forename: Karen E
authors.initials: KE
authors.lastname: Koch
authors.forename: Cornelia I
authors.initials: CI
authors.lastname: Ullrich
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000254:growth & development*; D001692:Biological Transport / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002367:Ricinus communis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D002454:Cell Differentiation / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D018526:Plant Transpiration / Q000502:physiology; D010941:Plant Tumors / Q000235:genetics / Q000382:microbiology; D011392:Proline / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism*; D014867:Water / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D014867:Water; D002245:Carbon Dioxide; D013395:Sucrose; D000040:Abscisic Acid; D011392:Proline; D005964:Glucosyltransferases; C022699:sucrose synthase; D043324:beta-Fructofuranosidase