title: Role of light and jasmonic acid signaling in regulating foliar phloem cell wall ingrowth development.
abstract: Phloem cells adjacent to sieve elements can possess wall invaginations. The role of light and jasmonic acid signaling in wall ingrowth development was examined in pea companion cells (CCs), Arabidopsis thaliana phloem parenchyma cells (PCs), and in Senecio vulgaris (with ingrowths in both cell types). Features characterized included wall ingrowths (from electron microscopic images), foliar vein density and photosynthetic capacity. In Arabidopsis, wall ingrowths were bulky compared with finger-like invaginations in pea and S. vulgaris. Relative to low light (LL), wall invagination in both CCs and PCs was greater in high light (HL). Treatment with methyl jasmonate in LL had no effect on CCs, but increased PC wall ingrowths. LL-to-HL transfer resulted in significantly less wall ingrowth in the fad7-1 fad8-1 (jasmonate-deficient) Arabidopsis mutant relative to the wild type. These results suggest that chloroplast oxidative status, via chloroplast-derived jasmonates, may modulate phloem structure and function. While CC wall ingrowths facilitate phloem loading by expanding the membrane area available for active uptake, one can speculate that phloem PC ingrowths may have two potential roles: to increase the efflux of sugars and/or protons into the apoplast to augment phloem loading; and/or to protect the phloem against pathogens and/or insects.
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.|Present address: Instituto de Investigaciones Agropecuarias, Unidad de Biotecnología, INIA Carillanca, Casilla 58-D, Temuco, Chile.
authors.forename: Véronique
authors.initials: V
authors.lastname: Amiard
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Demmig-Adams
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Mueh
authors.affiliation: Department of Plant Biology, 256 Plant Science Building, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Turgeon
authors.affiliation: Biology Department, Bowdoin College, Brunswick, ME 04011, USA.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Combs
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
authors.forename: William W
authors.initials: WW
authors.lastname: Adams
mesh_terms: D000085:Acetates / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure*; D003517:Cyclopentanes / Q000378:metabolism*; D008027:Light; D009154:Mutation; D054883:Oxylipins; D018532:Pisum sativum / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D052585:Phloem / Q000166:cytology / Q000648:ultrastructure*; D010788:Photosynthesis; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism*; D012674:Senecio / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; C072239:methyl jasmonate