A plant small heat shock protein gene expressed during zygotic embryogenesis but noninducible by heat stress

The nucleotide sequence(s) reported in this paper has been submitted to the GenBankTM/EBI Data Bank with accession number(s) Z95153.A small heat shack protein (sHSP) gene from sunflower, Ha hsp17.6 G1, showed expression patterns that differ from what is known for members of this gene family. The mRNAs of this gene accumulated in seeds during late desiccation stages of zygotic embryogenesis but not in response to heat shock in vegetative tissues, The failure to respond to heat shock was independent of the developmental stage after germination and shock temperature. Nuclear run-on analyses demonstrated that transcription from the Ha hsp17.6 G1 promoter is not induced by heat shock, This agrees with the presence, in this promoter, of sequences with little similarity to heat shock elements, Our results show an evolutionary divergence, in the regulation of plant sHSP genes, which has originated stress-responsive genes and nonresponsive members within this gene family, We discuss implications for mechanisms controlling the developmental regulation of sHSP genes in plants.This work was supported by Grant BIO96-0474 from Spanish Comision Interministerial de Ciencia y Tecnologıa and Grant CVI148 from Junta de Andalucı´a (to C. A. and J. J.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.Peer reviewe