S eeds are plant spores—desiccated, dormant cells in which metabolism and growth have been drastically slowed, so that the organism can wait out adverse conditions. This is especially important for plants, which cannot run away from environmental threats. Instead of motility, they use dormancy to outlast adversarial conditions caused by pathogens or severe weather. Indeed, some seeds remain via...

The concentration of abscisic acid in plants is regulated not only by biosynthesis, but also by metabolism. Abscisic acid is metabolized to phaseic acid via 8'-hydroxyabscisic acid, and phaseic acid is then converted to dihydrophaseic acid and its epimer. A quantitative analysis of these metabolites is important as well as that of abscisic acid to understand changes in the concentration of absc...

Some organisms have retained plastids even after they have lost the ability to photosynthesize. Several studies of nonphotosynthetic plastids in apicomplexan parasites have shown that the isopentenyl pyrophosphate biosynthesis pathway in the organelle is essential for their survival. A phytohormone, abscisic acid, one of several compounds biosynthesized from isopentenyl pyrophosphate, regulates...

An inhibitor extracted from short day treated Acer negundo leaves was compared to abscisic acid in 4 different solvent systems. The chromatographic properties of abscisic acid and the inhibitor were in very close agreement. Treatment of Acer negundo plants under non-hardening preconditions (long days) with either the inhibitor or abscisic acid increased hardiness after a hardening period of 3 w...

Abscisic acid was measured in developing cotton fruit (Gossypium hirsutum) by means of gas-liquid chromatography. High levels of abscisic acid occurred in correlation with abortion and abscission of young fruit, with low germination of immature seed, and with senescence and dehiscence of mature fruit. Declining or low levels of abscisic acid occurred in correlation with the period of most rapid...

The phytochrome-mediated attachment of mung bean (Phaseolus vulgaris L., var. Oklahoma 612) root tips on glass is quickly affected by indoleactic acid and abscisic acid at concentrations of 10 nm or less. Indoleacetic acid induces detachment, whereas abscisic acid induces attachment. Both plant regulators rapidly antagonize the action of the other. None of several cytokinins, gibberellins, and ...

Hormones which inhibit senescence in Rumex leaf tissue in the dark include gibberellic acid and the cytokinin zeatin. Abscisic acid accelerates senescence in this tissue. Other workers have proposed that cytokinins, but not gibberellins, interact with abscisic acid in senescing Rumex leaf tissue. The present study reinvestigates the question of interaction using measurements of chlorophyll degr...

Quantitative analyses of abscisic acid in the elongating zone of a single maize root (Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growt...

Cordycepin, an inhibitor of RNA synthesis in barley (Hordeum vulgare L.) aleurone cells, does not inhibit the gibberellic acid-enhanced alpha-amylase (EC 3.2.1.1.) synthesis in barley aleurone layers if it is added 12 hours or more after the addition of the hormone. However, the accumulation of alpha-amylase activity after 12 hours of gibberellic acid can be decreased by abscisic acid. The accu...