Effects of abscisic acid and high osmoticum on storage protein gene expression in microspore embryos of Brassica napus

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.94.3.875· OSTI ID:5770155

Wilen, R W; Mandel, R M; Pharis, R P; Moloney, M M ^[1]; Holbrook, L A ^[2]

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1. Univ. of Calgary, Alberta (Canada)
2. Oilseeds Biotechnology Research Centre, Calgary, Alberta (Canada)

Storage protein gene expression, characteristic of mid- to late embryogenesis, was investigated in microspore embryos of rapeseed (Brassica napus). These embryos, derived from the immature male gametophyte, accumulate little or no detectable napin or cruciferin mRNA when cultured on hormone-free medium containing 13% sucrose. The addition of abscisic acid (ABA) to the medium results in an increase in detectable transcripts encoding both these polypeptides. Storage protein mRNA is induced at 1 micromolar ABA with maximum stimulation occurring between 5 and 50 micromolar. This hormone induction results in a level of storage protein mRNA that is comparable to that observed in zygotic embryos of an equivalent morphological stage. Effects similar to that of ABA are noted when 12.5% sorbitol is added to the microspore embryo medium (osmotic potential = 25.5 bars). Time course experiments, to study the induction of napin and cruciferin gene expression demonstrated that the ABA effect occurred much more rapidly than the high osmoticum effect, although after 48 hours, the levels of napin or cruciferin mRNA detected were similar in both treatments. This difference in the rates of induction is consistent with the idea that the osmotic effect may be mediated by ABA which is synthesized in response to the reduced water potential. Measurements of ABA (by gas chromatography-mass spectrometry using ({sup 2}H{sub 6})ABA as an internal standard) present in microspore embryos during sorbitol treatment and in embryos treated with 10 micromolar ABA were performed to investigate this possibility. Within 2 hours of culture on high osmoticum the level of ABA increased substantially and significantly above control and reached a maximum concentration within 24 hours. This elevated concentration was maintained for 48 hours after culturing and represents a sixfold increase over control embryos.

• OSTI ID: 5770155
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 94:3; ISSN PLPHA; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSCISIC ACID
AUXINS
BIOLOGICAL EFFECTS
BRASSICA
CARBOXYLIC ACIDS
DEUTERIUM COMPOUNDS
DIFFUSION
EMBRYOS
FOOD
GENES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MESSENGER-RNA
MONOCARBOXYLIC ACIDS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OSMOSIS
PLANT GROWTH REGULATORS
PLANTS
PROTEINS
RNA
TRACER TECHNIQUES
VEGETABLES