Rapid stimulation of 5-lipoxygenase activity in potato by the fungal elicitor arachidonic acid

• Published in: Plant physiology (Bethesda) Vol. 100; no. 3; pp. 1448 - 1456
• Main Authors: Bostock, R.M, Yamamoto, H, Choi, D, Ricker, K.E, Ward, B.L
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-11-1992
• Subjects: ACIDE ARACHIDONIQUE; ACIDO ARAQUIDONICO; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Agronomy. Soil science and plant productions; Antibodies; Biological and medical sciences; Enzymes; Fatty acids; Fundamental and applied biological sciences. Psychology; Inductive reasoning; Leukotrienes; Lipid metabolism; LIPOXIGENASA; LIPOXYGENASE; Messenger RNA; Metabolism; Microbe-Plant Interactions; Microsomes; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; PHYTOPHTHORA INFESTANS; Plant physiology and development; SOLANUM TUBEROSUM; Soybeans; TUBERCULE; TUBERCULO; Tubers; Radiolabelling; Enzyme; Solanum tuberosum; Elicitor; Arachidonic acid; Fatty acids; Regulation(control); Vegetable crop; Enzymatic activity; Dicotyledones; Angiospermae; Plant tissue disc; Tuber; Isolation; Spermatophyta; Solanaceae; Lipoxygenase
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.100.3.1448

The activity of lipoxygenase (LOX) in aged potato tuber discs increased by almost 2-fold following treatment of the discs with the fungal elicitor arachidonic acid (AA). Enzyme activity increased above that in untreated discs within 30 min after AA treatment, peaked at 1 to 3 h, and returned to near control levels by 6 h. The majority of the activity was detected in a soluble fraction (105,000g supernatant), but a minor portion was also associated with a particulate fraction enriched in microsomal membranes (105,000g pellet); both activities were similarly induced. 5-Hydroperoxy-eicosatetraenoic acid was the principal product following incubation of these extracts with AA. Antibodies to soybean LOX strongly reacted with a protein with a molecular mass of approximately 95-kD present in both soluble and particulate fractions whose abundance generally corresponded with LOX activity in extracts. LOX activity was not enhanced by treatment of the discs with nonelicitor fatty acids or by branched beta-glucans from the mycelium of Phytophthora infestans. Prior treatment of the discs with abscisic acid, salicylhydroxamic acid, or n-propyl gallate, all of which have been shown to suppress AA induction of the hypersensitive response, inhibited the AA-induced increment in LOX activity. Cycloheximide pretreatment, which abolishes AA elicitor activity for other responses such as phytoalexin induction, did not inhibit LOX activity in water- or elicitor-treated discs but enhanced activity similar to that observed by AA treatment. The elicitor-induced increase in 5-LOX activity preceded or temporally paralleled the induction of other studied responses to AA, including the accumulation of mRNAs for 3-hydroxy-3-methylglutaryl coenzyme A reductase and phenylalanine ammonia lyase reported here. The results are discussed in relation to the proposed role of the 5-LOX in signal-response coupling of arachidonate elicitation of the hypersensitive response