title: Suppression and promotion of growth by ethylene in rice seedlings depends on ambient humidity.
abstract: We examined the effect of ethylene on the growth of rice seedlings (Oryza sativa L.) at various degrees of humidity. Ethylene significantly suppressed the growth of shoots when applied to seedlings grown under 30% relative humidity (RH), but promoted the growth of shoots when applied to seedlings grown under 100% RH. The application of gibberellic acid (GA(3)) promoted the elongation of shoots in seedlings grown under 30% and 100% RH. Ethylene inhibited the shoot elongation induced by GA(3) at 30% RH, but enhanced the elongation induced by GA(3) at 100% RH. These results indicate that ethylene can either promote or suppress the growth of rice shoots depending on ambient humidity, and that these actions of ethylene may be mediated through modulating the responsiveness of shoots to gibberellin.
authors.affiliation: Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan. azuma@kobe-u.ac.jp
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Azuma
authors.forename: Takenori
authors.initials: T
authors.lastname: Honda
authors.forename: Ayako
authors.initials: A
authors.lastname: Sadai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sasayama
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Itoh
mesh_terms: D005030:Ethylenes / Q000494:pharmacology*; D005875:Gibberellins / Q000494:pharmacology; D006813:Humidity; D012275:Oryza / Q000187:drug effects* / Q000254:growth & development*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects; D036226:Seedlings / Q000033:anatomy & histology / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D005030:Ethylenes; D005875:Gibberellins; C036216:ethylene; C007842:gibberellic acid