Plant Physiol, November 1999, Vol. 121, pp. 723-730
An Imperfect Heat Shock Element and Different Upstream Sequences
Are Required for the Seed-Specific Expression of a Small Heat Shock
Protein Gene1
Raúl
Carranco,
Concepción
Almoguera, and
Juan
Jordano*
Instituto de Recursos Naturales y Agrobiología, Consejo
Superior de Investigaciones Científicas, Apartado 1052, 41080 Sevilla, Spain
Chimeric constructs containing the
promoter and upstream sequences of Ha hsp17.6 G1, a
small heat shock protein gene, reproduced in transgenic tobacco
(Nicotiana tabacum) its unique seed-specific expression
patterns previously reported in sunflower. These constructs did not
respond to heat shock, but were expressed without exogenous stress
during late zygotic embryogenesis coincident with seed desiccation.
Site-directed mutagenesis of its distal and imperfect heat shock
element strongly impaired in vitro heat shock transcription factor
binding and transgene expression in seeds. Deletion analyses of
upstream sequences indicated the contribution of additional cis-acting
elements with either positive or negative effects on transgene
expression. These results show differences in the transcriptional activation through the heat shock element of small heat shock protein
gene promoters in seeds compared with the heat shock response. In
addition, they suggest that heat shock transcription factors and other
distinct trans-acting factors cooperate in the regulation of Ha
hsp17.6 G1 during seed desiccation.
1
This work was funded by the Spanish
Comisión Interministerial de Ciencia y Tecnología (grant
no. BIO96-0474) and by Junta de Andalucía (grant no. CVI148).
*
Corresponding author; e-mail fraga{at}cica.es; fax
34-95-4-62-40-02.
© 1999 American Society of Plant Physiologists
