title: Temperature-dependent changes of cell shape during heterophyllous leaf formation in Ludwigia arcuata (Onagraceae).
abstract: Although elongation of epidermal cells in submerged leaves is thought to be a common feature of heterophyllous aquatic plants, such elongation has not been observed in Ludwigia arcuata Walt. (Onagraceae). In this study we found that reduced culture temperature induced the elongation of epidermal cells of submerged leaves in L. arcuata. Since such submerged leaves also showed a reduction in the number of epidermal cells aligned across the leaf transverse axis, these data indicate that heterophyllous leaf formation in L. arcuata is partially temperature sensitive, i.e., the elongation of epidermal cells was temperature sensitive while the reduction in the number of epidermal cells did not show such temperature sensitivity. To clarify the mechanisms that cause such temperature sensitivity, we examined the effects of ethylene, which induced the formation of submerged-type leaves on aerial shoots at the relatively high culture-temperature of 28 degrees C. At 23 degrees C, ethylene induced both cell elongation and reduction in the number of epidermal cells across the leaf transverse axis, while cell elongation was not observed at 28 degrees C. Moreover, both submergence and ethylene treatment induced a change in the arrangement of cortical microtubules (MTs) in epidermal cells of developing leaves at 23 degrees C. Such changes in the arrangement of MTs was not induced at 28 degrees C. Factors involved in the temperature-sensitive response to ethylene would be critical for temperature-sensitive heterophyllous leaf formation in L. arcuata.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Sato
authors.forename: Maki
authors.initials: M
authors.lastname: Tsutsumi
authors.forename: Akane
authors.initials: A
authors.lastname: Ohtsubo
authors.forename: Kanae
authors.initials: K
authors.lastname: Nishii
authors.forename: Asuka
authors.initials: A
authors.lastname: Kuwabara
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nagata
mesh_terms: D048430:Cell Shape / Q000187:drug effects; D005030:Ethylenes / Q000494:pharmacology; D008870:Microtubules / Q000378:metabolism; D029594:Onagraceae / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013696:Temperature
chemical_list: D005030:Ethylenes; C036216:ethylene