Rooting response of mung bean cuttings to 1-aminocyclopropane-1-carboxylic acid and inhibitors of ethylene biosynthesis

Abstract

Cuttings taken from light-grown Vigna radiata (L.) R. Wilcz. cultivar ‘Berken’ seedlings were incubated for various periods in aminoethoxyvinylglycine (AVG) or α-aminoisobutyric acid (AIB) with or without auxin (indolebutyric acid). The inhibitors of ethylene biosynthesis reduced both the number of roots produced on cuttings and root growth rate. The inhibitory effect of AIB on root production was not reversed by 1-aminocyclopropane-1-carboxylic acid (ACC), while the inhibitory effect of AVG was partially reversed by ACC at high levels of auxin (10−4 M). Short treatments of ACC (up to 6 h) applied alone to cuttings did not affect rooting. However, prolonged exposure of cuttings to ACC (24 h) resulted in a significant decrease in root numbers, particularly when applied concurrently with auxin. The results support the hypothesis that a low threshold quantity of endogenous ethylene is required for optimal root production, and if tissue levels of ethylene fall below, or exceed, this threshold, root production and root growth rate may be inhibited.