Pathway of salicylic acid biosynthesis in healthy and virus-inoculated tobacco

Journal Article · Fri Oct 01 00:00:00 EDT 1993 · Plant Physiology; (United States)

OSTI ID:5696062

Yalpani, N; Leon, J; Lawton, M A; Raskin, I ^[1]

---

1. Rutgers Univ., New Brunswick, NJ (United States)

Salicylic acid (SA) is a likely endogenous regulator of localized and systemic disease resistance in plants. During the hypersensitive response of Nicotiana tabacum L. cv Xanthi-nc to tobacco mosaic virus (TMV), SA levels rise dramatically. We studied Sa biosynthesis in healthy and TMV-inoculated tobacco by monitoring the levels of SA and its likely precursors in extracts of leaves and cell suspensions. In TMV-inoculated leaves, stimulation of Sa accumulation is accompanied by a corresponding increase in the levels of benzoic acid. [sup 14]C-Tracer studies with cell suspensions and mock- or TMV-inoculated leaves indicate that the label moves from trans-cinnamic acid to SA via benzoic acid. In healthy and TMV-inoculated tobacco leaves, benzoic acid induced SA accumulation. o-Coumaric acid, which was previously reported as a possible precursor of SA in other species, did not increase SA levels in tobacco. In healthy tobacco tissue, the specific activity of newly formed SA was equal to that of the supplied [[sup 14]C] benzoic acid, whereas in TMV-inoculated leaves some isotope dilution was observed, presumably because of the increase in the pool of endogenous benzoic acid. We observed accumulation of pathogenesis-related-1 proteins and increased resistance to TMV in benzoic acid but no in 0-coumaric acid-treated tobacco leaves. This is consistent with benzoic acid being the immediate precursor of SA. We conclude that in healthy and virus-inoculated tobacco, SA is formed from cinnamic acid via benzoic acid. 27 refs., 7 figs., 1 tab.

• OSTI ID: 5696062
• Journal Information: Plant Physiology; (United States), Vol. 103:2; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
SALICYLIC ACID
BIOSYNTHESIS
TOBACCO
BIOLOGICAL PATHWAYS
DISEASE RESISTANCE
BENZOIC ACID
CINNAMIC ACID
LEAVES
NICOTIANA
TOBACCO MOSAIC VIRUS
CARBOXYLIC ACIDS
HYDROXY ACIDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MICROORGANISMS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PARASITES
PLANTS
SYNTHESIS
VIRUSES
550200* - Biochemistry