Ether-Soluble & Ether-Insoluble Auxins from Immature Corn Kernels

Abstract

Free and bound auxins of corn kernels (variety Golden Beauty) were extracted with cold ethanol (-10[degree]C overnight) and etherethanol (ether 48 hours at 25[degree]C followed by 90% cold ethanol) respectively, and the acid-ether, neutral-ether and aqueous (remaining after ether extraction) fractions were examined by paper chromatography. Essentially the same compounds were detected by both extraction procedures. No significant difference in the concentration of aqueous fraction auxins between the 2 extraction procedures was found. Therefore, the increased amount of indoleacetic acid (IAA) extracted by ether-ethanol as compared to cold ethanol was not released from the aqueous fraction auxins but from some different source. In acid-ether fraction IAA was critically identified. Several other compounds were detected in acid-ether and neutral-ether fractions but were not identified. In the aqueous fraction 6 compounds that were positive to chromogenic reagents and were also active in Avena growth test were detected. These compounds showed indole type ultraviolet spectra and gave IAA on alkaline hydrolysis. Release of arabinose on hydrolysis was indicated for only 1 of these compounds. It is suggested that auxins of aqueous fraction of corn kernels may represent a group of IAA-sugar conjugates that are not reserve or bound forms of auxins but may in fact represent the active forms of auxins in plants.