Auxins in bean (Phaseolus vulgaris L-cv. Zorin) seedlings

The amount and composition of auxins were investigated in bean seedlings (P haseolus vulgaris L.) cv. Zorin. Extracts of cotyledon, leaves, stems with shoots and roots were purified with Sep-Pak C-18 cartridges and analysed by HPLC with fluorescent and photodiode array detectors. Biological activity was determined with an Avena bioassay. The highest amount of indole-3-acetic acid (IAA) was detected in roots. In all analysed tissues bound IAA predominated. HPLC and bioassay confirmed IA A conjugates after hydrolysis with 7 N NaOH. In been seedlings, in addition to free IAA, some conjugates also showed biological activity.