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Biomedical subjects

E Prinsen

Publications and source records attributed to E Prinsen.

22 records · Page 2Linked to original sources
PubMed1993

Floral development and expression of floral homeotic genes are influenced by cytokinins.

Tobacco plants that are somatic mosaics for the expression of a cytokinin-synthesizing gene have viviparous leaves. Epiphyllous buds can be either vegetative or floral. Floral adventitious buds can be either normal or abnormal. Abnormalities of floral development correlate with: (i) a local activation of the cytokinin-synthesizing gene, (ii) a drastic increase in floral cytokinin content, and (iii) a decrease in the steady-state levels of mRNA homologous of the homeotic genes DEFA, GLO and PLENA of Antirrhinum majus. Thus, these data show in planta that cytokinins, a class of phytohormones, are able to alter the development of floral organs and to decrease the expression of three homeotic floral genes.

Base Sequence↗
PubMed1991

The indoleacetic acid-lysine synthetase gene of Pseudomonas syringae subsp. savastanoi induces developmental alterations in transgenic tobacco and potato plants.

The iaaL gene of Pseudomonas syringae subsp. savastanoi encodes an indoleacetic acid-lysine synthetase that conjugates lysine to indoleacetic acid. A chimaeric gene consisting of the iaaL coding region under the control of the 35S RNA promoter from cauliflower mosaic virus (35SiaaL) has been used to test if iaaL gene expression leads to morphological alterations in tobacco and potato. Transgenic tobacco plantlets bearing this construct have been shown to synthesize IAA-[14C]lysine when fed with [14C]lysine. In late stages of development, their leaves show an increased nastic curvature (epinasty) of the petiole and midvein, a finding suggestive of an abnormal auxin metabolism. The alteration is transmitted to progeny as a dominant Mendelian trait cosegregating with the kanamycin resistance marker. Transgenic potato plants harbouring the construct are also characterized by petiole epinasty. Moreover, 35SiaaL transgenic plants have an increased internode length in potato and decreased root growth in both tobacco and potato. An increased content of IAA-conjugates in leaf blade was found to correlate with the epinastic alterations caused by iaaL gene expression in tobacco leaves. These data provide evidence that IAA conjugation is able to modulate hormone action, suggesting that the widespread endogenous auxin-conjugating activities are of physiological importance.

Chromatography, High Pressure Liquid↗
PubMed1990

IAA synthesis and root induction with iaa genes under heat shock promoter control.

We have devised a heat shock-inducible indole-3-acetic acid (IAA) synthesis system for plant cells, which is based on the iaa genes of the Agrobacterium tumefaciens T-DNA and the heat shock promoter hsp70 of Drosophila melanogaster. Two DNA constructs were tested: one contains the iaaM gene linked to the hsp70 promoter (hsp70-iaaM) and encodes the production of indoleacetamide (IAM), the other contains hsp70-iaaM and the wild-type iaaH gene which codes for the conversion of IAM into IAA (hsp70-iaaM/iaaH). Heat shock-controlled IAM and IAA synthesis was tested on two levels: biochemically by measuring IAM and IAA levels in Kalanchoe stem segments infected with the two constructs, and morphologically by IAA-dependent root formation on Kalanchoe plants, on carrot discs and on tobacco leaf fragments. At both levels the responses were found to be controlled by the heat shock promoter. IAM levels of segments infected with hsp70-iaaM increased 6-fold upon heat shock induction to 240 pmol IAM per stem segment. The accumulation of IAA in segments infected with hsp70-iaaM/iaaH and heat-shocked was found to be more variable, possibly due to IAA transport and metabolism. Heat shock treatment of Kalanchoe plants and tobacco leaf fragments infected with hsp70-iaaM/iaaH led to a strong increase in root formation. On carrot discs, heat shock-specific root induction was also demonstrated, but the responses differed between individual carrots.

Amidohydrolases↗