Expression of a dehydrin gene during embryo development and drought stress in ABA-deficient mutants of sunflower (Helianthus annuus L.).
The synthesis of a particular class of proteins, the dehydrins, is a common response to drought in plants. Dehydrins are known to be synthesized by the cell in response to abscisic acid, which represents a link between environment and nuclear activity, though dehydrin genes may be expressed even constitutively. We have investigated the relationship between abscisic acid (ABA) and accumulation of a dehydrin mRNA in sunflower, in which a dehydrin cDNA (HaDhnla) was isolated. In particular, we studied changes in the steady-state level of dehydrin transcripts in two mutants for ABA synthesis and accumulation: nd-1 (an albino, non-dormant and lethal mutant with a very low ABA content and no ABA accumulation in response to stress) and w-1 (a wilty mutant, with reduced ABA accumulation) during embryo and plantlet development and drought stress. Differences between genotypes were observed through embryogenesis: w-1 shows a lower content of dehydrin transcripts in the early stages compared to control plants, indicating that ABA affects dehydrin mRNA accumulation; however, dehydrin transcripts level appears independent of ABA content in late embryogenesis. Also during drought stress in w-1 adult leaves, ABA is not quantitatively related to the steady-state level of the HaDhn1a transcripts. Finally, data on nd-1 mutant show a high level of dehydrin transcripts after drought stress in plantlet cotyledons and leaflets. These results indicate the existence of two regulation pathways of HaDhn1a transcripts accumulation, an ABA-dependent and an ABA-independent one, which may have cumulative effects.
Giordani
T
T
Scuola Superiore di Studi Universitari e di Perfezionamento S. Anna, Pisa, Italy.
Natali
L
L
D'Ercole
A
A
Pugliesi
C
C
Fambrini
M
M
Vernieri
P
P
Vitagliano
C
C
Cavallini
A
A
D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary; D004190:Disasters; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D006368:Helianthus / Q000235:genetics* / Q000254:growth & development*; D008969:Molecular Sequence Data; D018515:Plant Leaves; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000502:physiology
D018076:DNA, Complementary; D010940:Plant Proteins; D000040:Abscisic Acid