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Auxin protectors were isolated from potato tubers, potato sprouts and Synchytrium endobioticum incited tumors (potato wart). Three groups of protector were distinguished by molecular sieve chromatography. Dormant tubers contained relatively low levels of auxin protector compared to sprouts and tumor tissue. Tumors differed from normal tissues by their relatively high content of high molecular weight protector. The water-soluble high molecular weight protector from tumors was partially purified and shown to be a protein fraction (mol. wt 10 000 to 20 000) containing covalently bound caffeic and ferulic acids. The protein fraction contained unusually high levels of serine (15·4%), glycine (14·5%), glutamic acid (14·1%), proline (9·7%), aspartic acid (9·1%) and alanine (7·3%). A water-insoluble high molecular weight protector fraction was also isolated from wart tissue and shown to also contain covalently bound caffeic and ferulic acids but to differ from the water soluble fraction in its unusually high content of hydroxyproline (18%). It is suggested that cell wall proteins may be an important source of protector activity in potato wart tissue. |
