engleski

Auxin structure and activity

The dependence of auxin activity on molecular structure and conformation was studied for indole-3-acetic acid (IAA) and its derivatives bearing alkyl and halogen (F, Cl) substitutents at the benzene part of the indole nucleus. In the Avena coleoptile section straight growth test, 4,7- and 5,7-disubstitution with bulky Cl-atoms drastically reduced biological activity while akyl substituents with a linear two- to four-carbon backbone had a more gradual attenuating effect, supposedly by virtue of their flexibility. Conformational effects appear to be absent for the set of compounds evaluated here. More restrictive structural requirements were observed in a second auxin bioassay based on the developmental response of the deseeded pea pericarp.

auxin; indole-3-acetic acid; IAA; molecular structure; conformation; growth-promoting activity; coleoptile; pericarp; Avena sativa; oat; Pisum sativum; pea

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