From Amaranthus caudatus

W. F. Broekaert, W. Marien, F. R. Terras, M. F. De Bolle, P. Proost, J. van Damme, L. Dillen, M. Claeys, S. B. Rees, and J. Vanderleyden, Antimicrobial peptides from Amaranthus caudatus seeds with sequence homology to the cysteine glycine rich domain of chitin-binding proteins. Biochemistry, 31 (1992) 4308-4314. 

L. Wyns, D. Tourwe, and G. Van Binst, Location of the three disulfide bonds in an antimicrobial peptide from Amaranthus caudatus using mass spectrometry, J. Pept. Res., 49 (1997) 336-340. 

J. C. Martins, D. Maes, R. Loris, H. A. Pepermans, L. Wyns, R. Willem, and P. Verheyden, H-1 NMR study of the solution structure of Ac-AMP2, a sugar binding antimicrobial protein isolated from Amaranthus caudatus, J. Mol. Biol, 258 (1996) 322-333. 

Bruni, R., Guerrini, A., Scalia, S., Romagnoli, C. and Sacchetti, G. 2002. Rapid techniques for the extraction of vitamin E isomers from Amaranthus caudatus seeds Ultrasonic and supercritical fluid extraction, Phytochem. Anal. 13 257-261. 

The arsenal of plant defense peptides contains members capable of binding carbohydrate residues, namely /31-4 linked A -acetyl glucosamine residues that form the biopolymer chitin. The actual mode of action remains unclear. Antifungal and antimicrobial activity has been shown in vitro. For example Ac-AMP2 is a small disulfide-rich chitin-binding peptide isolated from the seeds of Amaranthus caudatus with antimicrobial activity. It differs from Ac-AMP 1 by one additional arginine residue at the C-terminus. The structure was determined by NMR and contains a cystine knot motif. Ac-AMP2 displays a so-called hevein domain partly... 

We found that the seeds of several other plants (e.g. of Raphanus sp. or of Amaranthus caudatus) are much more sensitive against inhibitors from oat caryopses than oats itself. This means that germination of such seeds is effectively inhibited if they are in the immediate neighborhood of oat caryopses even if germination of oats itself can take place. Oats are more active in allelopathy than other cereals (2). 

Since the use of techniques to measure IAA, bioassays have been important to discover PGR activity of many other compounds. Several bioassays for the PGR gibberellic acid (GA3) have been developed. One bioassay was based on reduction of amaranthin levels in Amaranthus caudatus (tassel flower) seedlings.63 This method was sensitive to GA3 from 0.01 to 1 mg L"1. GA3 was also bioassayed, based on anthocyanin reduction in tomato (Lycopersicon esculentum L.).62 Reduction of anthocyanin in tomato seedlings was linear from 10"5 to 10 mg L 1, and thus, this latter plant bioassay method was more sensitive. A multitude of bioassays for nonvolatile and volatile plant growth regulator compounds have been developed and their uses and limitations have been discussed.129 Since many allelochemicals have been shown to have relatively weak phytotoxicity (especially compared to herbicides), some of these bioassays that have been developed for detecting and quantitatively measuring PGR activity may be useful in allelopathy. 

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