title: Tight regulation of expression of two Arabidopsis cytosolic Hsp90 genes during embryo development.
abstract: The spatial and temporal distribution of expression of two cytosolic members of the AtHsp90 gene family was assessed during early development. In stressed transgenic plants bearing the AtHsp90-3 promoter, beta-glucuronidase (GUS) activity was strong in meristematic tissues. Expression was also detected in vascular tissues, leaf veins, siliques, and in pollen sacs. The promoter induced gene expression after heat shock in a time-course dependent manner. AtHsp90-1 promoter activity was low throughout the early stages of embryo development but high just before embryo maturation, with expression most prominent in cotyledons. AtHsp90-3 promoter activity was almost constant and restricted to the root and the cotyledon tips of the embryo. This highly specific spatial distribution of GUS activity changed when the tissues were heat-stressed. Both promoters were also active in unstressed mature pollen grains and during pollen germination. The results shown here indicate that different regulatory and developmental mechanisms control and differentiate the expression of the two cytosolic members of the Arabidopsis AtHsp90 gene family under normal conditions. The developmental and restricted pattern of expression of the AtHsp90-1 and -3 gene promoters in unstressed transgenic plants suggest prominent and distinctive roles of these two genes during different developmental processes.
authors.affiliation: Laboratory of Molecular Biology, Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Prasinos
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Krampis
authors.forename: Despina
authors.initials: D
authors.lastname: Samakovli
authors.forename: Polydefkis
authors.initials: P
authors.lastname: Hatzopoulos
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis*; D001483:Base Sequence; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D018384:Oxidative Stress; D011058:Pollen; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018841:HSP90 Heat-Shock Proteins; C466978:Hsp90-1 protein, Arabidopsis; C500134:Hsp90-3 protein, Arabidopsis