Asparagus decline: Autotoxicity and autotoxic compounds in asparagus rhizomes.
Asparagus (Asparagus officinalis L.) is a perennial vegetable, but its crop productivity and quality decrease gradually. One possible reason for "asparagus decline" is thought to be the autotoxicity of asparagus. However, the autotoxic property of asparagus rhizomes remains unknown. The objective of this study was to determine the potential role of rhizomes in the autotoxicity of asparagus. An aqueous methanol extract of asparagus rhizomes inhibited the growth of asparagus seedlings and six other test plants in a concentration-dependent manners: garden cress (Lepidum sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), ryegrass (Lolium multiflorum Lam.), timothy (Phleum pratense L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.). These results suggest that asparagus rhizomes contain autotoxic compounds. The extract was purified through several chromatographic steps with monitoring the autotoxic activity, and p-coumaric acid and iso-agatharesinol were isolated. These compounds inhibited the shoot and root growth of asparagus and two other test plants, garden cress and ryegrass, at concentrations higher than 0.1mM. The concentrations required for 50% inhibition of the root and shoot growth of these test plants ranged from 0.36 to 0.85mM and 0.41-1.22mM for p-coumaric acid and iso-agatharesinol, respectively. Therefore, these compounds may contribute to the autotoxicity caused by asparagus rhizomes and may be involved in "asparagus decline".
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan. Electronic address: hisashi@ag.kagawa-u.ac.jp.
Hisashi
H
Kato-Noguchi
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan.
Keisuke
K
Nakamura
Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522, Japan.
Osamu
O
Ohno
Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522, Japan.
Kiyotake
K
Suenaga
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan.
Nobuyuki
N
Okuda
D027761:Asparagus Plant / Q000187:drug effects*; D003373:Coumaric Acids / Q000737:chemistry / Q000494:pharmacology; D031747:Echinochloa / Q000187:drug effects; D031220:Lepidium sativum / Q000187:drug effects; D018545:Lactuca / Q000187:drug effects; D017705:Lignans / Q000737:chemistry / Q000494:pharmacology; D008129:Lolium / Q000187:drug effects; D000432:Methanol / Q000737:chemistry; D018517:Plant Roots / Q000187:drug effects; D018520:Plant Shoots / Q000187:drug effects; D027343:Rhizome / Q000737:chemistry*
D003373:Coumaric Acids; D017705:Lignans; C576853:iso-agatharesinol; D000432:Methanol
Allelopathy; Growth inhibition; Iso-agatharesinol; Phytotoxicity; p-Coumaric acid