Dose-dependent effects of malformin A1 on IAA-induced ethylene production in mung bean (Vigna radiate L.) hypocotyl segments

Abstract

Purified malformin A1 (cyclo-D-Cys-D-Cys-L-VaI-D-Leu-L-Ile), a cyclicpentapeptide toxin from Aspergillus niger, was applied to the hypocotyl segments of mung bean (Vigna radiata L.) seedlings to investigate its role in regulating ethylene biosynthesis. Production of ethylene was induced by treating the plants with 0.1 mM indole-3-acetic acid (IAA). When 0.1 pM malformin A1 was then applied, ethylene production increased and the activities of two key enzymes for its biosynthesis, 1-aminocyclopropane-l-carboxylic acid (ACC)-synthase (ACS) and ACC-oxidase (ACO), were also stimulated. However, at levels of I or 10 laM malformin A1, both ethylene production and enzymatic activities were significantly reduced. In the case of ACO, in vitro activity was regulated by malformin A1, independent of ACS activity or the influence of IAA. Furthermore, the conjugate form of ACC, N-malonyl ACC, was significantly promoted by treatment with 0.1 I~M malformin A1. These data suggest that malformin A1 can modulate ethylene production through diverse paths and that its effect depends on the concentration of the treatment administered.

Increased ethylene and decreased phenolic compounds stimulate somatic embryo regeneration in leaf thin section cultures ofDoritaenopsis hybrid

“…This response affects phenylpropanoid metabolism via 1-aminocyclopropane-l-carboxylic acid (ACC) (Song et al, 2001 ;Kim et al, 2004;Wu et al, 2006) and, hence, the accumulation of phenolic compounds (Tang and Newton, 2004). The accumulation of ethylene in a culturing system has been associated with either the inhibition or stimulation of shoot organogenesis and somatic embryogenesis in several plant species (Purnhauser et al, 1987;Cho and Kasha, 1989;Adkins et al, 1990;Chi et al, 1991;Tadeo et al, 1995;Goh et al, 1997;Mundhara and Rashid, 2006).…”

Anti-TMV Activity of Malformin A1, a Cyclic Penta-Peptide Produced by an Endophytic Fungus Aspergillus tubingensis FJBJ11

“…Research indicated that malformin A 1 has dose-dependent effects on auxin/indole acetic acid (IAA)-induced ethylene production in mung bean. Malformin A 1 can modulate ethylene production through diverse paths and its effect depends on the concentration of the treatment administered [ 20 ].…”