Hypocotyl formation during the epigeal germination of seedlings is under strict hormonal regulation. In a 3 d old Zinnia elegans seedling system, gibberellic acid （GA3） exerts an opposite effect to that exerted by l...Hypocotyl formation during the epigeal germination of seedlings is under strict hormonal regulation. In a 3 d old Zinnia elegans seedling system, gibberellic acid （GA3） exerts an opposite effect to that exerted by light on hypocotyl photomorphogenesis because GAz promotes an etiolated-like growth with an inhibition of radial （secondary） growth. For this reason, the effect of GA3 on the basic peroxidase isoenzyme from Z. elegans （ZePrx）, an enzyme involved in hypocotyl lignin biosynthesis, was studied. The results showed that GA3 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 GA3-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 GA3, with this effect matching the inhibitory effect of GA on the hypocotyl secondary growth.展开更多
基金supported by grants from the MEC (BFU2006-11577/BFI)-FEDERCARM (Programa de Generación de Conocimiento Científico de Excelencia de la Fundación Sneca,Agencia de Ciencia y Tecnología de la Región de Murcia en el Marco del Ⅱ PCTRM 2007–2010,project 08610/PI/08)
文摘Hypocotyl formation during the epigeal germination of seedlings is under strict hormonal regulation. In a 3 d old Zinnia elegans seedling system, gibberellic acid （GA3） exerts an opposite effect to that exerted by light on hypocotyl photomorphogenesis because GAz promotes an etiolated-like growth with an inhibition of radial （secondary） growth. For this reason, the effect of GA3 on the basic peroxidase isoenzyme from Z. elegans （ZePrx）, an enzyme involved in hypocotyl lignin biosynthesis, was studied. The results showed that GA3 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 GA3-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 GA3, with this effect matching the inhibitory effect of GA on the hypocotyl secondary growth.
