title: Downregulation of the basic peroxidase isoenzyme from Zinnia elegans by gibberellic acid.
abstract: Hypocotyl formation during the epigeal germination of seedlings is under strict hormonal regulation. In a 3 d old Zinnia elegans seedling system, gibberellic acid (GA(3)) exerts an opposite effect to that exerted by light on hypocotyl photomorphogenesis because GA(3) promotes an etiolated-like growth with an inhibition of radial (secondary) growth. For this reason, the effect of GA(3) on the basic peroxidase isoenzyme from Z. elegans (ZePrx), an enzyme involved in hypocotyl lignin biosynthesis, was studied. The results showed that GA(3) reduces ZePrx activity, similarly to the way in which it reduces seedling secondary growth. This hormonal response is supported by the analysis of the ZePrx promoter, which contains four types of GA(3)-responsive cis-elements: the W Box/O2S; the Pyr Box; the GARE; and the Amy Box. Taken together, these results suggest that ZePrx is directly regulated by GA(3), with this effect matching the inhibitory effect of GA on the hypocotyl secondary growth.
authors.affiliation: Department of Plant Biology, University of Murcia, E-30100, Murcia, Spain.
authors.forename: María Josefa López
authors.initials: MJ
authors.lastname: Núñez-Flores
authors.forename: Jorge
authors.initials: J
authors.lastname: Gutiérrez
authors.forename: Laura V
authors.initials: LV
authors.lastname: Gómez-Ros
authors.forename: Esther Novo
authors.initials: EN
authors.lastname: Uzal
authors.forename: Mariana
authors.initials: M
authors.lastname: Sottomayor
authors.forename: Alfonso Ros
authors.initials: AR
authors.lastname: Barceló
mesh_terms: D019659:Asteraceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D007527:Isoenzymes; C007842:gibberellic acid; D009195:Peroxidase