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ABSTRACT The root of the persistent weed, dandelion (Taraxacum officinale Weber), contains a predominant 18 kDa protein which undergoes small seasonal fluctuations in amount, increasing in the late autumn months, and declining in the spring. This protein has been purified and found to consist of two major isoforms of pI 5·56 and pI 5·49. A full-length cDNA has been obtained, coding for the pI 5·56 isoform, and the 156-amino-acid sequence deduced. The protein shows homologies in amino acid composition to several allergen and intracellular pathogenesis-related proteins. The deduced protein does not contain a signal peptide nor any known organelle-targeting sequences, and thus is likely to be cytosolic. Expression of the 18 kDa protein gene is exclusive to the roots and stem tissues; transcripts accumulate during the late autumn months, and decline in the early spring. Changes in the amount of protein in the root are much less. The mRNA for the 18 kDa protein is not present in the dry seed, but appears in the roots within 16–18 h from the start of imbibition, and is expressed constitutively thereafter. Although it is the predominant protein in dandelion roots, its properties are different from those commonly associated with vegetative storage proteins. [ABSTRACT FROM AUTHOR]

Maize seedlings (Zea mays L. cv. DK 246) grown for 1-4 days in the presence of abscisic acid (ABA) or triadimefon (a fungicide) demonstrated an enhanced ability to withstand the effects of a 3-h sub-lethal (40°C) or lethal (45°C) heat shock. Both the ABA and triadimefon treatments were applied solely to the roots of seedlings; however, the ability to withstand a heat shock was induced in both the root and the shoot. The level of protection provided by these agents was dependent upon the time that plants were exposed to them; prolonged exposure reduced tolerance to subsequent stress. [ABSTRACT FROM AUTHOR]