Inhibitor and Auxin Activity in the Avocado Fruit

Abstract

The wheat coleoptile elongation bioassay was used for determination of growth-promoting and growth-inhibiting substances in avocado (Persea americana Mill.) fruit tissues, during development and maturation. Growth-promoting activity was found in two zones on paper chromatograms developed with isopropanol: ammonia : water (10:1:1 v/v): Rf 0.30–0.50 and Rf 0.8–0.9. Growth inhibiting activity was found in three different zones: “A” Rf 0.0–0.2, “B” (abscisic acid) Rf 0.6–0.8, and “C” (l-acetoxy-2,4-dihyroxy-n-hepta-deca-16-ene) Rf 0.85–1.0. Higher levels of auxins were found in seed tissues than in the mesocarp. No correlation was found between fruit growth rate and level of extractable auxins in the mesocarp. The amount of abscisic acid (ABA) in the mesocarp was constant during fruit growth. A gradual and consistent increase in 1-acetoxy-2,4-dihydroxy-n-hepta-deca-16-ene was found during fruit growth, reaching a maximum when the fruit attained maturity.